1. Hospital Hill-Smith College engineering studio-2021
Feasibility Study of the Northampton
State Hospital Shared Use Path
Revision D: Archival
May 14th, 2021
Smith College
Picker Engineering Program
Design Clinic 2020-2021
Ruth Penberthy, Barb Garrison, Christian Madrigal, Karena Garcia
Sponsored by
The Northampton Office of Planning and Sustainability
NOPS Liaison
Wayne Feiden
MRGI Liaison
Gabriel Immerman
Technical and Liaisons and Advisors
Catherine Mulhern, Aaron Rubin, Susannah Howe
ii
Executive Summary
The following document reports on the work that was conducted during the 2020-2021 academic
year. It provides the Northampton Office of Planning and Sustainability (NOPS) and the Mill
River Greenway Initiative (MRGI) with a conceptual design for a bridge and a path along the
Mill River.
Background information on the project and a brief historical overview of the area is provided.
The area as it currently exists is introduced with maps and photos. Stakeholders including NOPS,
MRGI, and the greater Northampton community as well as their needs are discussed. These
needs help guide the design considerations while more standardized design requirements are
generated from relevant codes, standards, regulations, and laws.
Field work at the proposed bridge location is presented and includes a preliminary geotechnical
analysis and conclusions on soil strength. Other field work done for the path at large included
site visits, collecting elevation data, and slope analyses. The major findings are found in the body
of the report and the in-depth technical analyses are in the appendix. Further research was
conducted on the bridge and path regulations from governing bodies and engineering disciplines.
These findings are discussed and supplemented by geological information found from the site.
The conceptual design process for the bridge began with concept generation, expanded to
specific preliminary options, and concluded with more detailed work found in the appendices.
These options included a steel, bowstring truss pedestrian bridge with a possible lookout, a steel
Pratt truss with art along the structure, and a simple steel Pratt truss. The option that was ranked
most highly was the bowstring truss pedestrian bridge. The lookout was not considered due to
the final truss and railing design to be under or around eye level. CAD visuals and renderings for
this selected option are in the body of the report while more detailed drawings are located in the
appendix. A footing design for a shallow foundation is in the body of the report.
Work completed on the shared use path design includes a grading and drainage analysis with
possible solutions that follow the design requirements. In the report body, each area of concern
on the path is presented as the current issue and the recommended solution using maps,
renderings, and written findings. Additional detailed path visuals are located in the appendix.
Additional research and completed work for all of the mentioned subjects as well as
supplemental and detailed work that is left out of the body of this report is provided in the
relevant section of the appendix.
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Acknowledgements
Before recognizing those who helped us along the way, we would first like to acknowledge that
this project is based on Nonotuck land. We would also like to acknowledge the neighboring
Indigenous nations as well such as the Nipmuc and the Wampanoag to the East, the Mohegan
and Pequot to the South, the Mohican to the West, and the Abenaki to the North.1
We would then like to thank all of those who helped make this project and experience possible,
including but certainly not limited to our liaisons, Gaby Immerman, Catherine Mulhern, and
Wayne Feiden, and our Design Clinic Teaching Team (DCTT), Susannah Howe, Aaron Rubin,
and Mike Kinsinger. Gaby provided constant support and challenged our team to think about
how we could bring the community together in this space, Catherine gave us a much needed
crash course on structural design, and Wayne answered all of our many questions we ran into
along the way. All of the DCTT members are incredible examples of engineers and their
professionalism, confidence, and expertise were traits members of NOPS/MRGI tried to and
will continue to try to emulate everyday.
We would also like to give a special thanks to supportive faculty and staff on this project - Tracy
Tien and Jon Caris from the Smith College Spatial Analysis Lab who helped us with essential
GIS material, Sue Froelich who provided waders for important Mill River visuals, and Reid
Bertone-Johnson who provided excellent guidance and feedback on said visuals.
Last but not least, we would like to thank our friends, family, and peers for their support on this
project. Their questions about what we were up to, encouraging words, and attendance at
quarterly presentations meant the world to us.
1 https://www.fivecolleges.edu/natam/about-kwinitekw Last Accessed 4/28/21
iv
Table of Contents
Executive Summary ii
Acknowledgements iii
1. Introduction 1
2. Background and Motivation 2
2.1 History 2
2.1.1 Northampton State Hospital 3
2.1.2 Wireworks Factory 4
2.2 Motivation 5
2.3 Existing Paths 6
3. Project Stakeholders and Needs 10
4. Design Requirements 10
5. Design Development & Refinement 12
5.1 Overall Process 12
5.2 Existing Information 14
5.2.1 Familiarization with Civil Design Process 14
5.2.2 Trail Accessibility Guidelines 15
5.2.3 Site Geology 15
5.2.4 Site Elevations 15
5.2.5 Bridge Span and River Geometries 16
5.3 Field Work 18
5.3.1 Geotechnical Work 19
5.3.2 Site Visits 21
5.4 Conceptual Design and Selection 26
5.4.1 Pedestrian Bridge - Initial Concept Generation 26
5.4.2 Truss Bridge - Options and Final Selection 30
5.4.3 Decking Material 33
5.4.4 Bridge Structure and Beam Sizing 35
5.4.5 Abutments and Footings 37
5.4.6 Shared Use Path - Concerns and Solutions 39
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5.4.7 Shared Use Path - Bridge Connection 48
6. Final Design and Deliverables 49
7. Cost Analysis 57
8. Future Implementation 59
9. Summary 60
Appendix A: Gantt Charts 62
Appendix A1: Fall Gantt Chart 63
Appendix A2: Spring Gantt Chart 64
Appendix B: Traceability Matrix 65
Appendix C: Stakeholder and Design Requirement Development 66
Appendix C1: Stakeholder Development 66
Northampton Office of Planning and Sustainability 66
Mill River Greenway Initiative 67
Northampton community 67
Local environment 67
Appendix C2 Design requirement development 68
Appendix C2.1 Trail Accessibility Guidelines 68
Appendix D: Site Visit Photos 74
Appendix D1: February 28th 2021 74
Appendix D2: March 6th, 2021 77
Appendix D3 March 10th, 2021 79
Appendix D4: March 22nd, 2021 80
Appendix D5: March 29th, 2021 82
Appendix E: Preliminary Path Slope and Grading Analysis 84
Appendix E1: Problem Statement 84
Appendix E2: Methods 85
Appendix E3: Results and Discussion 87
Appendix E3.1: Section A 89
Appendix E3.2: Section B 90
Appendix E3.3 Section C 91
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Appendix E3.4 Section D 92
Appendix E4: Discussion of Preliminary Analysis 93
Appendix E5: Conclusion 97
Appendix F: Refined Path Slope and Grading Analysis 99
Appendix F1: Problem Statement 99
Appendix F2: Entire Existing Path Elevation 99
Appendix F2.1: Methods 99
Appendix F2.2: Results and Discussion 101
Appendix F3: Slope Areas of Concern Analysis and Solutions 102
Appendix F3.1: Methods 103
Appendix F3.2: Results and Brief Discussion 103
Area of Concern A 103
Switchback Suggestion 105
Area of Concern B 107
Area of Concern C 110
Area of Concern D 113
Appendix F4: Overall Suggestions for Existing Path 116
Appendix G: Geotechnical Literature Review 117
Appendix G1: Bearing Capacity 117
Appendix G2: Settlement 121
Appendix G3: Scour 123
Appendix H: Geotechnical Analysis of Proposed Bridge Site 127
Appendix H1: Various Geotechnical Tests 127
Appendix H1.1: First Field Test, 10/4/2020 127
Appendix H1.2: Second Field Test, 11/14/2020 134
Appendix I. Footing Calculations 142
Appendix I1: Bearing Capacity 143
Appendix I2: Contact Pressure 145
Appendix I3: Retaining Wall 146
Appendix J. Truss Research 149
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Appendix J1: The K Truss 150
Appendix J2: The Warren Truss 150
Appendix J3: The Pratt Truss: 154
Appendix J4: The Baltimore Truss: 154
Appendix J5: The Howe Truss: 154
Appendix J6: The Bowstring Truss: 155
Appendix K: Decking Material Research 158
Appendix K1 Wood: 158
Appendix K2: Steel 158
Appendix K3: Concrete 159
Appendix K4: Fiber Reinforced Plastic (FRP) 160
Appendix K5: Decking Selection - Matrix Scoring 163
Appendix L. Superstructure Concept Selection 164
Appendix L1: Bridge Concepts 164
Appendix L2: Initial Evaluation 164
Appendix L2.1: Reference Concept 164
Appendix L2.2: Rating Scales 166
Appendix L2.3: Weighted Criteria 167
Appendix M: Superstructure Design Analysis - Dimensional Calculations 168
Appendix M1: Loads and Hand Calculations for Beam Sizing 168
Appendix M2: Finite Element Analysis - Created by Technical Liaison Catherine Mulhern 179
Appendix N: Visuals - GIS Maps 190
Appendix N1: Current/Final Maps 190
Appendix O: Visuals - Footing CAD Designs 196
Appendix P: Visuals - Superstructure CAD Designs & Drawings 199
Appendix Q: Brief Ecological Impacts 205
Appendix Q1: Permitting 205
Appendix Q2: Wetlands Protection Act 206
Appendix Q3: Priority Habitat 207
Appendix Q4: Agricultural Land 208
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Appendix R: Cost Analysis 210
Appendix S: Drainage Matrix 211
Appendix T: Legislative Presentation 215
1
1. Introduction
The Northampton Office of Planning and Sustainability (NOPS) and the Mill River Greenway
Initiative (MRGI) have partnered with Smith College Design Clinic to create a conceptual design
for a bridge and shared-use path. The path will establish a connection from Village Hill/Hospital
Hill to the nearby Bay State neighborhood as seen in Figure 1. As a whole, the project will allow
safe access to and across the Mill River for pedestrians and bikers, provide a car-free route for
commuting students of Northampton High School, and will move the city of Northampton closer
to its net carbon neutral goals.
Figure 1: Open street map view of existing trail from the Smith College athletic fields to where
it ends near the abandoned Wireworks factory.
This project is part of a greater mission within the Commonwealth of Massachusetts to connect
shared-use paths across the state, spanning from Cape Cod to the Berkshires. Locally, the City of
Northampton’s comprehensive Open Space, Recreation, and Multi Use Plan 2 includes trail
extensions, modifications, and additions including culverts and bridges similar to this project.
The city is eager to show the Commonwealth and the local community how this project will
bring the community together and improve the quality of life in the Pioneer Valley.
The project is many years away from construction. The work completed during the 2020-2021
academic year includes a conceptual design for the shared use path and pedestrian bridge as well
as a presentation to give to NOPS to gain legislative support and aid in securing funding and
2 https://www.northamptonma.gov/DocumentCenter/View/1812 Last Accsessed 10/21/20
2
public approval for the project. The conceptual design includes an analysis of the current path
conditions with suggestions on how to adjust grading to meet ADA standards, a pedestrian
bridge designed to withstand various loading conditions, CAD drawings, substantiating
calculations, photo illustration renderings, an environmental impacts report, and a preliminary
cost estimate. The presentation for NOPS includes a description of what the process is to make
this conceptual design a reality. It includes graphics that promote this project’s potential with the
hopes of raising community interest and helping local government officials understand what
needs to happen next.
2. Background and Motivation
This section contains site history and discusses the communities impacted by this project. The
stakeholders and their needs are identified and contextualized within the purpose of the project
and design requirements.
2.1 History
An important mission of MRGI and this project is to connect people to the history of the Mill
River. The river, which provided water and power for early farmers and industry in
Northampton, is a vital and necessary part of our local landscape. As seen in Figure 2, there are
two historic sites at the east and west boundaries of the site: the Wireworks Factory to the east
and Village Hill/Hospital Hill (previously home to the Northampton State Hospital) to the west.
Figure 2: Historic and relevant sites, agricultural land, and the existing path near the Mill River.
3
Before European colonists arrived, the area around present-day Northampton was inhabited by
the Nonotuck people. They lived in settlements on top of Fort Hill, Meetinghouse Hill, and
Hospital Hill.3 They planted corn in the flat places between the hills, including on what is now
the Smith Athletic Fields. In the 17th and 18th centuries, the Nonotuck were displaced by
European colonists, who chartered the town of Northampton in 1654. The Mill River’s rushing
waters powered textile mills, paper mills, and other industries making Northampton grow. The
river flooded frequently, destroying mills and endangering lives. Flooding and its subsequent
destruction were still issues well into the 20th century, which prompted the U.S. Army Corps of
Engineers to divert the Mill River away from downtown Northampton to its present banks in
1940.
2.1.1 Northampton State Hospital
In 1858, a hospital for the mentally ill was built on the outskirts of Northampton 4 (See Figure 4).
It had luscious grounds and an innovative architectural design, meant to rehabilitate patients in
the Moralist tradition. Due to under-resourcing and delays in responding to medical advances,
the hospital became progressively larger and more crowded.
Figure 3: Photograph3 (date unknown) of the early Northampton State Hospital buildings, which
would become the core of a much larger complex as the hospital expanded.
3 http://millrivergreenway.org/the-river-2/a-short-history-of-the-mill-river-greenway/ Last Accessed 10/20/2020
4 https://northamptonstatehospital.org/ Last Accessed 10/23/2020
4
After the establishment of the Northampton Consent Decree, which declared that mental health
patients at state hospitals had a right to receive care in the least restrictive environment possible,5
the hospital was ordered to reduce its patient load to 50 in 1978. After years of financial
difficulties and changing medical models, the hospital closed its doors in 1993. The state hospital
was surplused and made available for sale in 1994 by Chapter 86 of the Acts of 1994. In a
nationwide search for developers, the Commonwealth received no economically viable
sustainable reuse proposals and the core of the facility, Old Main, was demolished despite a
significant community effort to save it in the summer of 2006 and 2007. Some of the
administrative and residential buildings survived, and the area formerly occupied by the hospital
is now a mixed-use development called Village Hill.6
2.1.2 Wireworks Factory
The Wireworks is a semi-abandoned industrial complex on Federal Street next to the proposed
bridge location. Local historian John Sinton reports that it started as a paper mill for the nascent
Hampshire Gazette, which was founded 1786 in the wake of Shays’s Rebellion. The paper mill
was built so the Gazette could spread its anti-rebellion agenda through the Pioneer Valley. Later,
it became home to a wire factory, which gives the site its colloquial name. The facility has
changed hands several times since then and is now owned by local landowner, Herb Berezin.
The Wireworks currently houses a driving school, but large abandoned brick and concrete
buildings and a vacant parking lot remain (see Figure 4).
5 https://www.mamh.org/advocacy/legal-advocacy/olmstead/rights-to-community-living Last Accessed 12/8/2020
6 https://valleyadvocate.com/2007/10/25/how-not-to-save-old-main-part-two/ Last Accessed 10/23/2020
5
Wireworks Parcel
Plan View
Isometric View
Closer Isometric View
Figure 4: Present-day Wireworks land parcel and aerial views 7.
2.2 Motivation
The Commonwealth of Massachusetts and its Department of Conservation and Recreation have a
vision to connect the state through a network of trails and greenways reaching from Cape Cod
through Metropolitan Boston to the Berkshires 8. Many regions of Massachusetts, including
Northampton, have begun to make this greenway a reality by building, expanding, and
improving their trail networks. Part of Northampton’s trail network is a shared use path,
accessible to bikers and walkers, which extends into parts of Easthampton, Southampton, and
Hadley, as well as Village Hill, Florence, and Leeds, which are villages within Northampton.
7 https://quantumlisting.com/listings/the-wireworks-building Last Accessed 4/16/21
8 https://www.mass.gov/doc/commonwelth-connections-report/download Last Accessed 12/8/20
6
This shared use path network has connected 70% of Northampton residents 9 to shared use paths,
which in some areas, runs right along the historic Mill River. The State Hospital Shared Use Path
would provide a vital link to this network because it would expand use of the trail network by
making the already popular river and adjacent open space more accessible. Just as important, it
would reconnect the public with the outdoors, local history, and scenery of the Mill River.
2.3 Existing Paths
The Pioneer Valley, consisting of Hampden, Hampshire, and Franklin counties, is home to an
existing and expansive shared use path network 10. Looking more closely in Northampton, the
project motivation becomes clear. In Figure 5, the red square approximately outlines the
boundaries of the project.
Figure 5: Pioneer Valley bike map with the project site contained in the red square.
9 https://www.northamptonma.gov/1346/BikeWalk-Trails Last Accessed 10/21/20
10 https://ma-northampton.civicplus.com/DocumentCenter/View/11125/Bicycle-Map-regional Last Accessed
4/27/21
7
From Figure 5, it is important to observe that there are shared use paths (purple lines) around the
red box but there are none inside the box. However, although it is not considered a shared use
path, there is a trail that does exist in this area. That existing trail can be seen in Figure 2.
There are multiple access points to this existing trail. For consistency, the trail’s starting point
will always be at the Smith College Athletic Fields entrance. Figure 6, provides a visual of this
entrance as well as its location on the map. The yellow box highlights the rusty, chain link fence
that exists at this entrance.
Figure 6: The Smith College entrance to the existing path.
Moving west along the existing path, the next marker indicates the Village Hill asphalt
connection to the existing path. Figure 7 shows what this entrance currently looks like. To the
left of the caution sign is the Village Hill residential community. In front of the sign where the
photographer was standing is where the existing path lies. The caution sign indicates the end of
the asphalt path.
8
Figure 7: The entrance to the existing path from Village Hill.
Moving further west past the first agricultural field, the historic Ice Pond is visible from the
existing path. The yellow circle in Figure 8 highlights the historic infrastructure.
Figure 8: The historic Ice Pond.
When moving past the Ice Pond and continuing north, pedestrians pass a second agricultural
field which indicates the Wireworks factory is near. Figure 9 provides visuals for that view.
9
Figure 9: Point of view while facing north towards the Wireworks factory. Here the
photographer is standing north of the Ice Pond but still south of the second agricultural field.
The end of the existing path is near the Wireworks factory. Figure 10 shows both the
approximate proposed bridge site, and the Wireworks in one image.
Figure 10: Visual of the approximate bridge site to the left and the Wireworks boxed in blue on
the right.
Wireworks
10
While the existing trail currently provides users with a scenic view of the river, the purpose of
the proposed shared use asphalt path is to increase this area’s accessibility for not only more
people to enjoy recreationally, but to also provide carbon-free transportation options. Paving the
path and building a bridge will allow a broader demographic of community members to engage
with the river. People with mobility challenges will be able to witness the flow of the river. A
paved, drainable, and plowable surface will invite pedestrians to use this route any time of the
year without worrying about mud or snow. This public works project puts the needs of the
community and their comfort first while keeping the preservation of the landscape at the
forefront.
3. Project Stakeholders and Needs
The major stakeholders in this project are the Northampton Office of Planning and Sustainability
(NOPS), the Mill River Greenway Initiative (MRGI), the greater Northampton community, and
the local ecology. In depth details about each of these stakeholder needs can be found in
Appendix D, but Table 1 below summarizes them.
Table 1: Summary of the project’s stakeholders and their needs.
Stakeholder Needs
NOPS ● Existing agricultural land and ecosystem is not disturbed
● Americans with Disabilities Act Compliance (10’ minimum
path width, 5% grading)
● Emergency vehicle path access
● ~$4 million budget
MRGI ● Historic sites are preserved
● Project alignment with mission statement
Northampton
Community
● Trail accessibility and safety
Local Ecology ● Minimize scour, erosion, and water contaminants
4. Design Requirements
The project summary provided to the team in the beginning of the academic year stated several
key design requirements. The team conducted additional research to address all the requirements
that state regulators, federal regulators, and the community would have for this project. It is
important to note that bridge construction and construction on wetlands or near farmlands are
highly regulated in Massachusetts (see Appendices C2.1 and Q).
11
Key design requirements 11 for the trail include:
● Durable surface: The trail should be paved in a durable material which permits easy
biking, wheelchair access, and walking. The city prefers an asphalt surface.
● Grade: The trail must maintain a grade of 4.5% or below, as specified in the Americans
with Disabilities Act (ADA). Short sections of the trail can go up to 8% grade, but this
should be avoided if possible.
● Cross Slope: The trail tread should be outsloped (sloped away from the hillside) by 2%.
This will allow water that comes on to the trail to flow off downhill and not be channeled
down the trail.
● Width: The path must be at minimum ten feet wide, and may decrease to eight feet if ten
feet is physically impossible.
The following design requirements are necessary for trails, however due to the landscape and
grading around our region, these requirements were satisfied purely by the natural landscape. No
further design work was needed to satisfy these requirements.
● Grade Reversals: While the trail will generally follow the contour of the land, it will also
most likely either be climbing or descending slightly. However, a sustainable trail should
also reverse its grade often (from down to up and vice versa, “surfing the hillside”). This
will reduce the watershed of any given section of trail, prevent water from collecting and
running down the trail, and reduce any erosion potential. Most trails should include grade
reversals every 20 to 50 feet.
● Half Rule: A trail’s grade (percent slope) should not be any greater than half the grade of
the hillside that it contours along. For example, if the slope of the hill the trail runs along
is 16%, then the grade of the trail should be no more than 8%. This will allow water to
flow across the trail, off the trail and continue down the slope. This is especially
important along gentle slopes.
The key requirements for the bridge are heavily impacted by the loads it will potentially
experience which can be grouped into dead loads and live loads. A dead load includes any load
permanently attached to the bridge including its own weight and its abutments. A live load is the
weight of people, vehicles, and other moving objects on the bridge. The live loads considered are
11 https://www.mass.gov/doc/dcr-trails-guidelines-and-best-practices-manual/download LastAccessed 10/21/20
12
those from the Strength I scenario referenced in the AASHTO LRFD Bridge 12 Design
Specifications, (“AASHTO Highway”) which are:
● Pedestrian Live Load: The bridge must withstand the weight of a tightly packed bridge,
up to 90 psf as specified in the AASHTO LRFD Manual for Pedestrian Bridges.
● Vehicular Live Load: The bridge must withstand the weight of an ambulance or
maintenance vehicle at any point along the bridge.
● Dead load: The bridge must withstand its own weight.
Strength I is the main scenario being considered because it is the load combination that is
appropriate for a design in its conceptual phase such as this one. It is a conservative enough
approach to make an educated attempt at structural design.
The bridge must also consider flooding conditions in the region to understand any further design
constraints or requirements. Considering the 100-year flood is adequate for a conceptual design.
The analysis will ensure there is free-board over that flood elevation.
5. Design Development & Refinement
This section aims to demonstrate the process of how the conceptual designs of the bridge and
path reached their final designs. The section begins with an overview of the work done
throughout the year then moves into more details about that work. Existing conditions are
investigated and that information along with field work helped inform decisions made for the
conceptual designs of both the bridge and the path.
5.1 Overall Process
The academic year was split into five periods - quarters 1 and 2 in the Fall 2020 semester, J-term,
and quarters 3 and 4 in the Spring 2021 semester. Table 2 lays out the general workflow process
by section. Due to the COVID-19 pandemic, most of the work for quarter 1, quarter 2, and J-
term was done remotely. Ruth Penberthy was the only team member on-site during Fall 2020.
All four team members were on campus for quarters 3 and 4 during the spring. This impacted the
way in which work was done since it was not feasible for all team members to visit the site until
February 2021.
12 American Association of State Highway and Transportation Officials, LRFD Guide Specifications for the Design
of Pedestrian Bridges, December 2009, Last Accessed 4/28/21
13
Table 2: Summary of work by quarter. The four cells on the top of the matrix point to the four
quarters of the year with their respective task directly below.
Quarter one heavily focused on research and information gathering. Learning more about the
site, its history, and stakeholder needs was prioritized. Preliminary points of concern on the path
were identified and information was sourced on the civil design process and pedestrian bridges.
Understanding what potential soil analyses were needed was also underway. This quarter heavily
focused on creating organized project structure and developing a loose plan and schedule for the
quarter two, J-Term, and quarter three.
In quarter two, more specific work on the type of river crossing was completed, the fundamentals
of geotechnical analyses were reviewed, and a plan to test the soil near the proposed bridge site
was drafted. The preliminary points of interest identified in quarter one were explored more, and
it was discovered that the major concerns were due to noncompliant grading and a drainage
concern. By the end of quarter two, it was concluded that a prefabricated truss pedestrian bridge
would be used.
During January recess, the data collected from the geotechnical testing in quarter two was
analyzed. The conclusion that resulted from the analysis was that the soil was mostly
cohesionless, which led to the conclusion that there would be no major issues with construction
14
in the area. This is discussed more thoroughly in section 5.3. Field Work, and a full report on all
geotechnical work conducted is in Appendix H. Additionally, Preliminary 2D and 3D versions
of the bowstring truss and parts of the path began to be created with best guesses for many of the
dimensions.
In quarter three, the structural analysis of the bowstring truss began and visuals using CAD
SketchUp, and ArcGIS Pro were created. For each identified area of concern on the existing
path, solutions were explored and brought back to the liaisons for feedback. Based on that
feedback and the research done by team members, solution recommendations were made. These
solutions included switchback routes, drainage options, and cut and fill. The end of quarter three
marked the end of any large scale technical design changes for either the bridge or the path. At
the end of the quarter, all visuals that would be used for final deliverables were near complete.
Quarter four’s focus was to finish the final designs for the bridge and the path based off of the
feedback received from the two design reviews from quarter three. The final designs are in
section 6. Final Deliverables. The end of quarter four was dedicated to documentation of the
ecological impact, cost analysis, and all other general documentation needed to fully represent
the work completed throughout the academic year. The final deliverables that were completed
include this final written report, a final presentation delivered on May 5th, a presentation for the
project liaisons to have for legislative and funding purposes (found in Appendix T), a poster,
and an additional archival report.
5.2 Existing Information
This section describes the work needed for the bridge and path design and starts with an
understanding of the general civil design process used to shape the year’s work. It discusses the
existing requirements for designing an accessible shared use path, existing soil conditions found
with preliminary field work, an analysis of the site’s current elevation data, and the present-day
river conditions.
5.2.1 Familiarization with Civil Design Process
There are approximately four phases of a civil engineering project from the perspective of an
engineer: conceptual, design development, construction documentation, and construction. It was
made clear that this project is the first conceptual phase. Since this is preliminary design work,
basic soil data is collected and a rough structural layout for the bridge is developed. The
structure’s footprint is laid out, path routes are decided, and systems within the project are
defined. Understanding the extent of the project’s work helped narrow the scope of the project as
it allowed for more flexible design and less strict detailed work. Where applicable, educated
attempts and assumptions were made and details such as joint connections for the bridge or exact
construction drawings for the path were not included in the project scope.
15
5.2.2 Trail Accessibility Guidelines
With a project receiving funding from the federal, state, and local governments, it is expected
that this activity follows specific guidelines that these organizations must uphold. This
stipulation directly applies to this project as it is receiving funding from the federal, state, and
local levels of government. In order to comply with these gubernatorial standards, research was
conducted on what guidelines would be impacting the design of the trail and bridge. There are
many guidelines at each level of government when it comes to the accessibility of shared use
trails and bridges. Appendix C2.1: Trail Accessibility Guidelines discusses the key guidelines
from each level of government respectively. Table C1 in Appendix C2.1 includes (but is not
limited to) links to resources that contain guidelines and provides more detail than this section.
The information in Appendix C2.1 can be summarized by the following bullet points:
● The United States Forest Service Trail Accessibility Guidelines (FSTAG) legally pertains
to trails within National Parks.
○ This project is not in a National Park, but the FSTAG does provide reasonable
technical provisions acceptable to the state and local levels.
● The main two guidelines to consider for trail accessibility are its surface and its slope.
● State guidelines legally pertain to trails in state parks.
○ This project is not in a state park but should follow the state guidelines, which
closely resemble, if not completely adopt, the national guidelines.
● Softer technical provisions on sustainable trail design are provided in the Department of
Conservation and Recreation’s Trail Guidelines and Best Practices Manual.
5.2.3 Site Geology
According to ArcGIS data, the soil at the proposed bridge site on the eastern bank of the river
near the Wireworks Factory was categorized as Pootatuck fine sandy loam whereas the western
bank of the river near the agricultural fields was said to be made up of both Rippowam fine
sandy loam and Pootatuck fine sandy loam. This meant that the western side, where one of the
bridge abutment foundations would be located, consisted of granular soils that were well drained
year-round. It is important to note, once again, that this information was obtained from ArcGIS
data. These soil characteristics were checked and discussed further in section 5.3 Field Work.
5.2.4 Site Elevations
The path elevations were obtained using ArcGIS Pro software. These elevations were relevant
for redesigning areas with poor drainage, finding a route to pave, and ensuring the path was
compliant with ADA grading. A preliminary analysis of elevation began with identifying the
location of areas that exceeded an ADA compliant grade. This analysis is detailed in Appendix
E. This general elevation analysis was quickly refined using the existing path which is depicted
in Figure 1 in section 1. Introduction and the elevation profile in Figure 11 was used to
16
identify major areas of concern. This figure is not in true scale in order to better visualize the
elevation variation. The true scale elevation profile is located in Appendix E along with other
details on how this figure was produced.
Figure 11: Elevation profile that details the variation of the existing path as one travels from the
Smith Athletic Fields towards the proposed bridge site.
As mentioned, this elevation profile was used to identify specific areas of concern. The details on
the exact areas of concern are provided in section 5.4.5 Shared Use Path.
5.2.5 Bridge Span and River Geometries
In Fall 2020, the bridge span was estimated to be 100 feet by visually examining the slope of the
riverbed in ArcGIS online. This preliminary measurement did not reflect the exact location of the
bridge or abutment placements, but it did provide a rough estimate of the bridge length.
17
Figure 12 is a preliminary visual from ArcGIS online that depicts the measurement process. The
topographic basemap map is overlaid with an orange-and-white slope data layer. The dark
orange seen on either side of the river represents an area of relatively steep slope compared to the
lighter colored regions. By drawing a line that spanned the regions of steep slope, the team
estimated that the bridge was 100 feet long.
Figure 12: ArcGIS Online map depicting the bridge location. Bridge must span river banks,
which are the two, dark orange parallel lines crossing the map diagonally. Saturation levels
denote change in elevation.
In quarter three, a more detailed look at the river’s cross section was taken, which revealed the
span of the bridge needed to be 130 feet. Figure 13 shows a map with similar topographic lines
as seen in the previous figure. Similarly to Figure 12, the topographic lines are quite dense on
either bank. The light blue line that crosses the river and a portion of the land on either side was
used to create a stack profile of the river. Then, a cross-section of the river was extracted from
the profile. The resulting elevation profile from the extracted data is visualized in Figure 14.
18
Figure 13: A map of the proposed bridge site with light grey contour lines and a light blue line
used to complete the Stack Profile of the river cross section.
Figure 14: Complete stack profile of the river cross section with a box highlighting the riverbed
cross section.
The span of the bridge must comply with Massachusetts River and Stream Crossing Standards
and the Massachusetts Department of Transportation (MassDOT) span of 1.2 times the length of
bankfull river. The abutments can be placed in the floodplain of the river as long as they are
designed to withstand possible forces they may encounter as a result (i.e. 100 year flood event).
5.3 Field Work
This section discusses the field work conducted on the existing path and proposed bridge
location including geotechnical testing, path concern investigations, and visual data collection.
19
5.3.1 Geotechnical Work
The soil characteristics from ArcGIS were confirmed by a preliminary geotechnical analysis
conducted on the west side of the river. “Introduction to Geotechnical Engineering” by Holtz and
Kovacs 13 was used as a reference for the soil testing protocols and procedures. Using the samples
collected, a sieve analysis was conducted and with the necessary calculations, grain size
distribution graphs were created as seen in Appendix H, Figures H5 and H8. This analysis
allowed the team to conclude that the soil is well graded and on the cusp of being classified as
SP, gravelly sands with little or no fines, or SM-SW, sand with silt.
The bridge site’s soil conditions were further analyzed during a site visit on November 14, 2020.
A team used a DGSI standard hand auger and a dynamic cone penetrometer to collect soil
samples and data to use for further analysis on soil strength. Five soil samples were collected,
bagged, and sealed for future experimental testing. From this site visit more information was
known about the conditions than the first soil test. Initial observations suggested possibilities of
glacial deposits or large boulders around 8.5 feet below the ground and showed no signs of
significant clay deposits. The GSD graphs for two of the deeper soil samples, C and E, are seen
in Figure 15 and 16, respectively. Based on this information, the preliminary soil classification
assumption of SP was confirmed for these deeper soil samples as well. With this cohesionless,
dense soil assumption, there were no major concerns about the feasibility of construction.
13 Holtz, Robert D. and Kovacs, William D. “Introduction to Geotechnical Engineering.” Chapters 1, 4, 8, 9, and
10.
20
Figure 15: The grain size distribution curve for sample C.
Figure 16: The grain size distribution curve for sample E.
A CAD drawing of the concluded soil profile is also provided by Figure 17. Further details
about this specific site visit is in Appendix H1.2. As mentioned before, this soil profile is an
21
approximation of the west side of the Mill River closest to the agricultural fields. Since it was
prohibited to enter the other side of the property near the Wireworks factory, it was assumed that
both sides of the river would have the same soil profile. This is a large assumption, and it is
recommended that more thorough geotechnical tests be conducted on both sides of the river to
ensure all existing soil information is known and accurate.
Beginning in early 2021, the soil samples from the November 14th site visit were analyzed to
determine soil strength and friction. With this information, bearing capacity calculations were
conducted and used to make conclusions on the necessary foundation design that is further
explained in Appendix I.
Figure 17: CAD drawing of the approximate soil layers on the west side of the river closer to the
agricultural fields.
5.3.2 Site Visits
Aside from the site visits dedicated to the geotechnical field work, additional visits were
conducted. One included a visit after a heavy rain storm event on the afternoon and evening of
October 16, 2020. Ruth Penberthy walked the path the next morning on October 17th to see
where there were any drainage or flooding issues. Most of the path was still damp but was easily
walkable. There was only one area that was flooded. Its location is seen in Figure 18.
22
Figure 18: Topographical map of drainage concern area, outlined in pink, next to Village Hill.
The area was flooded with approximately three inches of storm runoff that extended for
approximately one-hundred feet as seen in Figure 19. This area currently has stone pavers that
act as a small drain to channel water down slope, however with serious storm events this
infrastructure is not suitable to manage heavier rain events and flooding. A possible solution to
this issue is presented in section 5.4.6 Shared Use Path - Concerns and Solutions.
23
Figure 19: Image of flooded path with approximately 3” of rain water. Photograph by Ruth
Penberthy.
A similar site visit was conducted to determine important access points to the existing path. The
most important gateways are those located around the Village Hill residential development and
the entrance that connects the existing path to the Smith College athletic fields. There is another
connection between the Northampton Community Gardens and the existing path, but they are
both not immediately connected so that connection is not prioritized. In Figure 20, the start of
the shared use path connection to Village Hill has been paved with asphalt. This is the same
picture shown in Figure 7 in section 2.3 Existing Paths as a standalone image. In Figure 21, the
Smith gateway will need development and signage to make the shared use path inviting and
welcoming to pedestrians. This is also the same picture used in Figure 6 in section 2.3 Existing
Paths.
24
Figure 20: Image of the Village Hill residential community connection, facing Village Hill.
Photograph by Ruth Penberthy
Figure 21: Image of the Smith College athletic fields gateway connection, in need of
development. Photograph by Ruth Penberthy
Most of the other site visits were conducted with the purpose of understanding which parts of the
path are not ADA compliant due to steep grades. These visits consisted of collecting geospatial
data to later analyze in ArcGIS. This field work in combination with the ArcGIS analysis helped
identify the exact areas of concern and quantify how these areas were noncompliant with the
25
necessary 4.5% ADA grade. More detailed work on this is in Appendices E and F. Appendix E
includes the preliminary path slope and grading analysis which was completed with approximate
geospatial data provided by NOPS. Appendix F includes the refined path slope and grading
analysis on the new and more accurate geospatial data collected by the team. These areas of
concerns are discussed in section 5.4.6 Shared Use Path - Concerns and Solutions. Figure 22
depicts all identified areas of concern which are labeled in red as A, B, C, and D. Each section is
covered individually in 5.4.6 Shared Use Path - Concerns and Solutions.
Figure 22: After field work and site visits, these are the areas of concern due to grading in all
parts and one drainage issue in “B.”
Several hours of field work were dedicated towards resolving the first slope concern, “A.” The
preliminary work for this solution is presented here because it took more experimentation during
the site visits to arrive at the final solution presented in section 5.4.6 Shared Use Path - Concerns
and Solutions. New paths and possible switchbacks were walked and the geospatial data were
recorded using a gps smartphone app. Figure 23 demonstrates the experimental switchbacks that
were walked in order to refine the final switchback.
26
Figure 23: Preliminary switchback solutions to propose for slope concern “A.”
Final visits to the path and proposed bridge site were mainly done to obtain images of the site for
photoshop work and using SketchUp. These images and additional site photos are in Appendix
D.
5.4 Conceptual Design and Selection
This section aims to clearly lay out the conceptual design and selection process for both the
bridge and the path. The bridge’s process will go first, followed by the shared use path.
5.4.1 Pedestrian Bridge - Initial Concept Generation
This section discusses the process of designing the pedestrian bridge. It outlines concept
generation, discusses concept selection, and touches on calculations for the final product.
27
This project requires a bridge to allow pedestrians, cyclists, and the occasional vehicle to cross
the Mill River. Literature review indicates that there are several bridge superstructures that could
be employed in this project: cable-stayed, arch, girder, and truss. The non-bridge option for
spanning the river is to lay several box culverts side-by-side (Figure 24).
Figure 24: A real life example of what these side-by-side culverts would potentially look like.
Bridges can vary in height, width, span, and structure, and are usually used when impeding the
flow of a waterway is not an option. Culverts are similar in purpose but different in design than a
bridge as culverts are typically embedded in the soil and only span about 20 feet. See Table 3
below for a summary of options.
28
Table 3: A table summarizing the initial crossing conceptual design with incompatible options in
red, possible options in yellow, and best option in green.
Bridge
Type
Diagram Appropri
ate?
Limiting
Attributes
Description
Cable
No Cost Expensive and optimized for
longer spans. Creates higher
long term maintenance
needs.
Arch
No Height and
Arch
Proportional
ity
Arch height may become
excessive after designing in
ice flow clearance.
Girder/
Precast
Concrete
Maybe Span and
Aesthetics
Single unit precast bridges
are for short distances (<50’)
without middle support and
are not used as style pieces.
Truss
Yes Span Many different variations
and appropriate span limits.
Culvert
No Aesthetics
and
Environment
al Impact
Large environmental impact,
specifically on the river flow.
All of these options, except for the truss bridge, can be ruled out because they are incompatible
with basic requirements of the project.
The culvert was suggested as a significantly lower-cost option for crossing the river. It is
unsuitable, however, because it does not meet the environmental standards set out by partnering
organizations. The Mill River Greenway Initiative and NOPS are not interested in solutions that
obstruct the river, as these would harm the ecosystem and might be dangerous in river-icing
conditions, and such solutions would probably not receive the necessary permits. The river
29
crossing is about 100 feet wide from bank to bank, which would require about five box culverts
to cross. The more likely solution is two or three box culverts with infill to meet the road. Both
solutions add hard interruptions to the flow of the river and might be dangerous in flood
conditions. The appearance of the bridge is one of the major concerns for NOPS and MRGI, and
the culvert option does not mesh aesthetically with the natural scenery of the path, nor the
historic Wireworks site.
Girder bridges can be ruled out for the same reasons as the culvert: cost and aesthetics. A precast
concrete bridge would require a support in the middle of the river, which is unacceptable because
it impedes flow, not to mention that a foundation in the middle of the river would greatly
increase cost. A girder bridge with a girder stiff enough to support a 130 foot span would be
quite deep, possibly deep enough that the bridge would be at more risk for damage from flooding
or ice flow.
Cable-stayed bridges are too expensive to consider, and they are not appropriate for the type of
crossing in this project. Cable-stayed bridges are more economical at lengths of 200-400 feet,
which is far longer than the current crossing 14.
Arch bridges that place the arch below the bridge would require a very high arch for a span of
130 feet, which would result in either the feet of the arch dipping below the waterline or a very
tall bridge, both of which are not good uses of money. In addition, if the arch is too low, seasonal
ice blocks that flow down the river could damage the bridge. The aesthetics appeal of the arch
can be captured with an arched bowstring truss.
The remaining appropriate bridge option was the truss bridge. Truss bridges are common in New
England, so a new truss bridge would fit aesthetically into the landscape. They are a moderate-
cost option and stiff without being overly tall at the 130-foot required span. There is also
significant flexibility in the arrangement of the members for achieving different aesthetic aims.
This allowed for multiple truss designs to be considered as the bridge’s aesthetics and cost could
be altered by manipulating these design elements. The next section will summarize the different
types of truss structures being considered, pros and cons associated with them, and ultimately,
the truss shapes that will be used moving forward.
14 http://www.roseke.com/types-of-pedestrian-bridges/
30
5.4.2 Truss Bridge - Options and Final Selection
A truss bridge can be made with a variety of truss layouts. Research was done on trusses for
pedestrian bridges to determine which were appropriate for this project. A detailed writeup of
this research can be found in Appendix J. A brief summary is provided in Table 4, below.
Table 4: A summary of several truss shapes and their pros and cons.
Truss Type Pros Cons
K Truss Appropriate span,
aesthetically unique
Increased complexity, and
thus, cost and time
Warren Truss Simple, appropriate span,
works well with distributed
load
Not very unique
Double Intersection Warren Appropriate span, works well
with distributed load
Increased complexity
Lattice Appropriate span, works well
with distributed load
Increased complexity
Pratt Truss Appropriate span, commonly
used, strength, statistically
determinant
Not very unique
Howe Truss Appropriate span, commonly
used, strength, statistically
determinant
Not very unique
Bowstring Truss Appropriate span, aesthetics,
commonly used
Increased complexity relative
to Pratt, Howe, and Warren
Baltimore Truss Appropriate span, strength Common for railroads
These truss types appear to be the most popular selections when it comes to trail and pedestrian
bridges. The Warren, Pratt, Howe, and Bowstring Trusses were the recommended types of truss
based on the presented research. The truss list was simplified further into just the Pratt and
Bowstring trusses. This was done because the Warren and Howe trusses were very aesthetically
and functionally similar to the Pratt truss.
31
Three main conceptual designs were generated, focusing on aesthetics and public engagement
with the bridge. They varied in structural material, which truss was used, where a lookout would
be, and where art could be installed. Each considered option had the following variables:
● SUPERSTRUCTURE: Bowstring truss or Pratt truss.
● STRUCTURE MATERIAL: Steel or wood.
● LOOKOUT LOCATION: Middle (see Figure 25) or Abutment (i.e. a bench or placard).
● ART LOCATION: Sides of bridge over the water, railings near abutments
Figure 25: A bowstring bridge with a lookout, or “bubble”, in the middle.
These three options and their combinations of variables are summarized by the following table:
Table 5: The three main concepts considered for the bridge component of the project.
Bowstring Option Pratt Option #1 Pratt Option #2
Superstructure Bowstring Pratt Pratt
Structural
Material
Steel Steel Steel
Lookout
Location
Middle Abutment None
Art Location Railing near abutments Sides over water Railings near abutments
These options were then placed into a concept scoring matrix of important factors and scored to
quantitatively compare them, which is documented in detail in Appendix L. The selection
criterion in the matrix were abutment impact, carbon footprint, construction cost, maintenance
cost, visual weight, and interactive potential.
● Abutment Impact measures abutment expense. Heavier bridges or bridges that catch more
wind require larger, more expensive abutments.
● Carbon Footprint is the environmental impact of bridge materials, construction process,
and maintenance; this is a direct design consideration from NOPS and MRGI.
32
● Construction Cost is the cost of initial installation, including material transportation.
Budget requirements require costs that will total to less than an anticipated $4 million
dollar budget per project statement.
● Maintenance Cost is the expense required to ensure upkeep of the bridge superstructure
and other necessary costs to ensure longevity of the project. NOPS would like to
minimize maintenance costs.
● Visual Weight subjectively considers how bulky the bridge is. Stakeholders including
NOPS and MRGI value a bridge with minimal visual impact on its surroundings, so it’s
important to make a bridge that is as visually “light” as possible. Lightness means slender
beams and small superstructure - smallness of superstructure was prioritized over slender
beams.
● Interactive Potential subjectively considers whether the bridge contains interactive
elements that encourage people to spend time on or near the bridge. Showcasing the
beauty of the site and getting people to spend time in nature are some of the stakeholders'
priorities.
Table 6: Concept Scoring Matrix
Bowsting Pratt Option 1 Pratt Option 2
Selection Criteria Weight Rating
Weighted
score Rating
Weighted
score Rating
Weighted
score
Abutment Impact 0.25 3 0.75 2 0.5 3 0.75
Carbon Footprint 0.075 3 0.225 2 0.15 3 0.225
Construction Cost 0.2 2 0.4 2 0.4 3 0.6
Maintenance Cost 0.2 4 0.8 4 0.8 4 0.8
Visual Weight 0.2 4 0.8 3 0.6 3 0.6
Interactive
Potential 0.075
5
0.375
2
0.15
4
0.3
Sum Total 1 3.35 2.6 3.275
Rank 1 3 2
According to the matrix, the options from ranks first to third are Bowstring, Pratt Option 2, and
Pratt Option 1. See Figure 25 (above) for a sample bridge that illustrates the chosen option. With
superstructure chosen, the next steps were to decide on the decking material, structural beam
sizing, and abutments.
33
5.4.3 Decking Material
There are five common decking materials for pedestrian bridges: wood, steel grid, concrete, fiber
reinforced plastic (FRP), and ballast. The research done on each type of decking material can be
found in Appendix K. Ballast and steel grid were not viable because they prevented snow
removal. The advantages and disadvantages of each viable material. are summarized in Table 7.
Table 7: The different decking materials and their pros and cons.
Decking Material Pros Cons
Wood Rustic/natural look
Inexpensive
Simple/Common
Longevity
Maintenance
Hazardous chemical
pretreatment
Susceptible to rot, warp,
insects
Concrete Simple/ Common
Strength
Aesthetics
Environmental Impacts
Maintenance
FRP Lightweight
Low Maintenance
Non Corrosive
Non Conducive
Relatively Expensive
Uses different tools
Inexperience in industry
With these pros and cons in mind, a final matrix for comparing the different decking materials
was created.
34
Table 8: A weighted matrix for comparing the different decking materials.
Decking
Material
Environmental
Hazard
Maintenance Impact
Resistance
Weight
(Heaviness)
Cost Aesthetics Total
Wood 3 3 3 1 5 5 4.1
Concrete 2 2 5 2 5 2 2.9
Asphalt 2 2 5 2 5 2 2.9
FRP 4 5 5 5 2 5 4.05
Weight .2 .1 .05 .05 .25 .35 -
The design criteria in this matrix include Environmental Hazard, Maintenance, Impact
Resistance, Weight (as in heaviness), Cost, and Aesthetics. Environmental Hazard is whether the
material is hazardous to the environment. Maintenance is how much upkeep is necessary. Impact
Resistance is how much the material will deform permanently on impact. Weight is how heavy
the material is. Cost is how much the material costs. Aesthetics is how well the material works
with the natural space of the area and how well it aligns with stakeholders’ wants.
● Environmental Impact comes from both MRGI and NOPS because these stakeholders
want to minimize the negative impact on the environment this bridge will have in the
area. It is also the responsibility of engineers to consider the impacts their work has on
the environment, so it is important to acknowledge how the decking material contributes
to impacts on the environment.
● Maintenance is considered because the City of Northampton will be responsible for the
maintenance of the bridge once it is installed. NOPS is an entity of the City and a major
stakeholder in this project, so ensuring that maintenance will not be a cause of extra cost
and annoyance is important.
● Impact Resistance comes from the fact that the bridge will experience a variety of traffic
from pedestrians, bicycles, and even vehicles at times, so on a concentrated impact, the
decking material should not permanently deform. The material should also be plowable,
so blades from a snow plow should not damage the material.
● Weight would be a concern as far as installation goes. Heavy materials are going to need
heavier equipment for hauling and installation. Lighter materials may make
transportation and installation easier.
35
● Cost is always a concern on any project and ways to minimize costs are always desirable.
This project is being funded by MassDOT and other governmental funds which means
there is a limited amount of money for the project.
● Aesthetics is a concern for MRGI, NOPS, and the community, and the decking color and
material will contribute to the overall aesthetic of the bridge. The bridge should not seem
out of place in the natural area. Ideally, the bridge will not take away from the river and
the natural scenery.
The rating scale chosen was a 1-5 scale for each criterion. Table K3 summarizes the 1 and 5
scores.
Based on the total scores of the matrix and discussion with stakeholders, wood and FRP decking
are the two ideal materials that also align with the wants of MRGI and NOPS. After further
discussion with NOPS, wood was decided to be the final chosen material because of cost and the
prevalence of wood decking for existing pedestrian bridges in Northampton.
5.4.4 Bridge Structure and Beam Sizing
During J-term, research was done on how the floors of pedestrian bridges were structured. The
goal was to practice the process of selecting beam sizes on the simple-to-analyze floor before
moving on to the more complex truss.
The structure for the floor was chosen from a conversation with liaison Catherine Mulhern and a
visual analysis of existing pedestrian bridges. A large beam connecting each truss and on top of
this, stringers in the other direction; on top of the stringers lie the deck planks. More specific
details on how these structures are joined together are out of the scope of the conceptual design
phase.
AASHTO Highway Bridges and technical liaison Catherine Mulhern were consulted to build an
understanding of the Load Resistance Factor Design methodology used by professional bridge
designers. In LRFD, loads are multiplied by factors that account for uncertainty of analysis and
material variability, among other things. These factored loads are added together in different
combinations such as Strength I, Service IV, and Extreme Event II that simulate situations the
bridge might need to withstand. From these load combinations, force effects such as shear,
moment, and buckling are calculated for each component.
Due to time and scope constraints, the single load combination considered was a pared-down
version of Strength I that included dead load, vehicular live load, and pedestrian live load.
Strength I is a standard load combination that simulates the everyday loads a structure must bear,
and is appropriate for a conceptual design. Per AASHTO Pedestrian, simultaneously analyzing
36
the pedestrian and vehicular loads was not necessary, so the live load (vehicular or pedestrian)
that created the greater force effect for each piece was selected. It was assumed that if the bridge
could withstand these conservative loads, then this would align with the amount of information
needed in the conceptual design phase.
In quarter three, the components of the truss were sized. A truss has several pieces - the top and
bottom chords, the vertical and diagonal cross-pieces. A truss bridge also includes the deck
planks, stringers, and foot beams that comprise the floor. Hand calculations were done to
determine the sizes of each floor piece, following the LRFD process. For each piece:
1. A mechanics problem was set up with a certain load, aiming to calculate a certain force
effect such as shear. The load was placed to create the maximum force effect in the piece.
(A truck will be in a different place to create maximum shear than maximum bending.)
2. The force effect was calculated using mechanics methods. Equations for maximum shear
and moment in certain beam loading scenarios were referenced from AISC 8th ed.
3. This was repeated for other loads.
4. The force effects from dead load and the greater live load were multiplied by factors and
added together to create the nominal resistance that the beam must have.
5. The factored resistance required was calculated by multiplying nominal resistance by a
final factor, phi.
6. Required beam section modulus was calculated from factored resistance.
7. This process was repeated for the other force effect, and the larger of the two calculated
section moduli was taken.
8. A beam with a conservative section modulus was chosen from a table of structural steel
shapes.
From this analysis, sizes for the floor beams were chosen. Hand calculations were laid out for the
truss, but the analysis was sufficiently complex that it was deemed time-inefficient to attempt to
analyze the entire truss by hand. To solve this, a finite element analysis of the truss was created
by liaison Catherine Mulhern, which took loads as inputs and confirmed the sizes of each beam.
See Appendix M2.
Final beam sizes are given in Table 9 below.
37
Table 9: Summary of Superstructure Component Sizes
Component Material Nominal Size
Deck plank Douglas Fir Select Structural
grade
5x10 Plank
Stringer Steel C4x7.25
Floor Beam Steel W6x16
Truss Top Chord Steel HSS 12x6, 1/2" wall
Truss Bottom Chord Steel HSS 10x6, 1/2" wall
Truss Vertical Steel HSS 3x3, 1/4" wall
Truss Diagonal Steel HSS 3x3, 1/4" wall
5.4.5 Abutments and Footings
The overall process of the abutment design is discussed here, but the calculations that were
necessary for the exact geometry deduction are in Appendix I. “Soils and Foundations” by Liu
and Evett 15 was consulted and used as a reference throughout every step of the design process
including the initial research phase, calculations, and sizing process. After it was confirmed that
the project would be moving forward with a truss pedestrian bridge, work on the design of the
bridge abutments and footings began. Similar to the bridge itself, the abutments and footings
needed to be able to withstand the same loads, vehicular and pedestrian. A load unique to the
abutments and footing especially was the load the soil imposed on the structure. Before
exploring the soil loading, more information was needed on what kind of soil was present. It is
important to note that the side of the river closest to the Wireworks was not accessible, so a large
assumption that it shares roughly the same soil characteristics as the other side of the river was
made. After collecting and analyzing geotechnical data on the site soil, it was decided that a
shallow foundation would be best. Furthermore, according to the text, a continuous footing
would be most appropriate for this project. Before moving on to the geometry of the footings, the
approximate location for both needed to be determined. This prompted a more detailed look at
the profile of the riverbed because there were two main options: have the footings closer to the
river embankment, exposing the footing or further from the embankment, leaving nothing but the
tops of the footing partially visible. The first option kept the span of the bridge closer to 100ft
15 Liu, Cheng and Evett, Jack. “Soils and Foundations.” Seventh Edition. Chapters 7, 13, 9.
38
which would be cheaper, but also disturbed the river embankment. The second option would lead
to a longer span of the bridge, increasing cost, but would leave the river embankment virtually
undisturbed. With our stakeholders in mind, disturbing the river bank was not an option, so it
was decided that the footings would be further from the bank.
Knowing the type of footing and general location of each footing, an initial design was drafted.
This initial design was heavily based off of Soils and Foundations because in order to make
adjustments, a preliminary geometry was needed. This initial footing design attempt, however,
ended up being too shallow, too narrow, and technically impossible to construct.
After conversations with Professor Rubin and consulting Chapter 13: Retaining Wall Structures
of Soils and Foundations a more reasonable abutment design was reached. The table below
summarizes the geometries of both the initial and final footing designs. It is important to notice
the drastic differences in the depth and base dimensions. Figure 26 shows the detailed CAD
drawing of the final design.
Table 10: Summary of initial and final footing design geometries.
Design Depth
(ft)
Base
(ft)
Thickness
(ft)
Toe
(ft)
Heel
(ft)
Initial 7 5 1 2 2
Final 24 12 2 2 8
39
Figure 26: The CAD detail for a possible footing design.
5.4.6 Shared Use Path - Concerns and Solutions
The following section outlines the major concerns of the path and their subsequent solutions.
These concerns and solutions are supplemented by respective maps and real pictures of the site.
There are three primary issues with the trail that prevent it from being converted to a shared-use
asphalt path as-is: several sections of the trail are too steep (>5% grade), there is a drainage issue
on a flat portion of the site at Hospital Hill, and there is major erosion near the historic ice pond.
Refining the preliminary analysis of the proposed shared use path resulted in the identification of
four major regions of concerns that can be visualized by Figure 27.
40
Figure 27: Path overview with relevant markers for important landmarks along the proposed
path.
These sections were chosen as a result of field work on the existing trail that further confirmed
these sections held potential for improvement. The main cause for concern of these path
segments were rooted in suspicion that they had non compliant ADA grading. As addressed by
the analyses of the four major sections of concern along the path, it was concluded that all of
these sections were candidates for cut and fill. The process is as intuitive as it sounds; sections of
the path that are steep would be either cut and/or filled to level the ground of the path segment
resulting in a grading change that would be most compliant with ADA. On the other hand, a
switchback for Slope Concern - A was explored to serve as an alternative for cut and fill. This
suggested switchback would cut across as shown in Figure 29 and is about 155 meters in length.
This switchback is simply an iteration of a path alternative that could be used to meet ADA
compliance. It was shown as part of analyzing this switchback option, it had reduced the average
grading of Area of Concern A from 7.6% to 5.5% (details in Appendix F). While the improved
grading percentage did not entirely fall below the 4.5% threshold it does hold promise in
reducing the average grade of this path segment significantly. Therefore, this option could be
further explored when paving the shared use path.
41
Figure 28: Area of Concern A and its location along the proposed shared use path.
The solution recommendation for this area of concern is a switchback. Figure 29 shows this
switchback on the map in blue. This switchback option was investigated and it was concluded
that a 4.5% grade would be possible. This switchback will allow pedestrians and cyclists to
safely traverse down the hill to the rest of the path, but it does not mean that the concerning part
of the existing path will cease to exist. Pedestrians and cyclists may still use that path; this is
simply a recommendation for an ADA compliant alternative.
42
Figure 29: Area of Concern Solution - A which is a switchback that complies with ADA
grading.
The second region of concern was Area of Concern - B (Figure 30) which was also analyzed due
to the suspected noncompliant ADA grading that was experienced as data was being collected.
The analysis that is summarized in Appendix F3.2 confirms that this section of the path does not
comply with ADA requirements and sits at an average grading of 6.3% across the 60 meter
section.
Figure 30: Area of Concern B and the location of this section along the proposed shared use
path with a real-life visual for context.
6.3%
43
The drainage concern addressed in 5.3.2 Site Visits is an additional concern in section B as well.
The recommended solution for this slope concern (and the following slope concerns) is to use a
cut and fill methodology to reach ADA compliance (other details in Appendix F). Figure 31
provides a conceptual look as to what this area could look like if it were cut, filled, and paved.
Figure 32 shows what a typical cross section of what this pavement could look like for the entire
path.
Figure 31: Conceptual visual of the solution for section B.
4.5%
44
Figure 32: A typical cross section of the path pavement theoretically applied to all parts of the
proposed path.
As far as the solution for the drainage concern, advantages and disadvantages of a culvert,
permeable pavement, a cross-slope, and a vegetated swale/rain garden were reviewed (Appendix
S). An overview of the pros and cons of each solution led to the conclusion that this drainage
concern might be best addressed by implementing a combination of a cross slope and a vegetated
swale/rain garden. This is simply a preliminary suggestion as a result of brief analysis, but this
drainage concern would be better addressed with a thorough investigation of the site in future
work.
The third section of major concern labeled Area of Concern - C was a path section that occurs
after the drainage concern and is about 100 meters in length (Figure 33). This path section was
further analyzed, and it was found that the total path section had an average grading of 3.6%
(Appendix F3.2). This average value is deceivingly compliant as it is below the 4.5% threshold
permitted by ADA, but it is important to note that there was a 10 meter section within this path
segment that had a grading average of 6.1%. Like Area of Concern - B cut and fill is suggested
45
and details are in Appendix F.
Figure 33. This a map that displays the location of Area of Concern C along the proposed shared
use path.
Moreover, there is a steep dropoff on the left side of the path closest to the agriculture fields. A
fence along this steep dropoff is thought to be an important safety measure. On the less technical
side, this part of the path offers an expansive view of the agricultural fields which could be a
prime location for signage that informs passersby of the importance and history of the land.
Figure 34 shows what this design solution could potentially look like.
6.1%
46
Figure 34: A possible rendering of the solution for part C.
The last section of concern was located near the historic Ice Pond and is pinpointed by Figure
35. This section is known as Area of Concern - D, a 60 meter long section along the path closer
to the site for the proposed pedestrian bridge. For this portion of the path it was also confirmed
that the 4.5% ADA grade requirement was not met and had an average grading of 4.8%
(Appendix F3.2). In addition to the slope concern here, there is also an erosion issue (Figure 36)
as well as some existing infrastructure near the area. These two issues are not explicitly
addressed in this report, but a fence would be ideal near the erosion concern; not to control the
erosion, but to provide a safe barrier from the steep slope that is near this area. Overall cut and
fill is suggested for this region and details on a suggested profile are in Appendix F.
47
Figure 35. The final area of major concern along the proposed shared use path highlighted on
the map of the proposed trail.
Figure 36: The erosion issue near the Ice Pond.
Figure 37 shows what this path could possibly look like once properly graded and paved. There
is also some signage present on the bottom right hand corner that could serve as a place where
pedestrians can learn more about the historic Ice Pond.
4.8%
Erosion
48
Figure 37: Paved and graded solution to the Ice Pond area with signage informing the public on
this site’s history.
5.4.7 Shared Use Path - Bridge Connection
The final part of the path not yet covered is how it connects to the bridge. Figure 38 shows what
the path could look like as it rounds the corner toward the bridge, but not quite close enough to
see it. Here, it is important to notice the signage that should be posted that indicates which way
the bridge is.
Figure 38: Possible shared use path headed toward the bridge.
49
Rounding the corner of this path, the bridge becomes visible and the approach comes into view.
A scaled rendering of this is presented in Figure 39.
Figure 39: The front view of the bridge with its connection to the shared use path in view.
6. Final Design and Deliverables
The final design for the shared use path is pictured below in (Figure 40). The route generally
follows the existing footpath from Smith College to the Wireworks Factory. The new design
solves Slope Concern - A by avoiding a piece of the existing path with a new, less steep
switchback section. The design solves slope issues B, C, and D by regrading the trail at those
locations.
50
Figure 40: Map of Proposed Shared Use Path Route. Map shows final path route, bridge, and
landmarks over an OpenStreetMaps basemap to highlight how the project fits in to the existing
trail network. Connection to Smith College is highlighted in purple.
This section includes a summary of the final deliverables for both the path solutions and the
bridge design. The process of how these solutions and designs were created was covered in the
previous sections of the report thus far, and even more detailed notes on individual steps can be
found in the appendices. That being said, most of this section will include finished renderings of
proposed design solutions created in SketchUp.
Per the Project Summary, it was expected that at the end of the year, the team would provide the
following:
● Conceptual bridge design that details aesthetics of the bridge along with chosen materials
and truss type.
● Conceptual trail design summarizing points of major concern alongside suggested
methods of addressing them.
● Computer Aided Design (CAD) drawings of the bridge abutments and trail
● Calculations to substantiate engineering decisions made on bridge and trail
● Compelling renders of both the bridge and trail for public consumption
● Presentation to pitch the project to funding agencies and community
51
Going bullet-by-bullet, the conceptual bridge design, its truss type, materials, and thus,
aesthetics, were covered in section 5.4 Pedestrian Bridge but is summarized again under the
bridge visuals provided.
Figure 41: The final conceptual bridge design.
Similarly, section 5.4.6 Shared Use Path - Concerns and Solutions summarized the major
concerns and solutions to the trail, but the specific SketchUp visuals for each solution are
presented below.
Pictured below is the cut and fill solution to part B. This rendering was done in SketchUp and
includes an example of what the path could look like with asphalt pavement. The design calls for
a two foot shoulder on either side of the path, but in this perspective, only the shoulder on the left
side of the path can be seen.
52
Figure 42: Solution for part B of the path, cut and fill to correct grading and an asphalt
pavement.
The next image is a SketchUp rendering of the solution to part C of the path. As mentioned
previously, although the average grade along this part is 3.6%, there is a portion that is 6.1%, so
some cut and fill will be needed. Also, a possible wooden fence was added to this area because
on the side of the path with the fence, there is a steep drop off that users should keep a safe
distance from. This fence provides a physical safety barrier and doubles as future erosion control.
Something that should also be noticed is the signage added to the fence. This area provides a
possible location for users to not only stop and look out onto the agricultural fields, but also learn
about what land they are looking at exactly.
53
Figure 43: Solution to part C with shoulder, asphalt pavement, wooden fence barrier, and
possible signage concepts shown.
Continuing down the path, the first part of the next solution shown is for the erosion issue near
the start of part D. Similar to the solution for part C, a wooden fence is added to keep pedestrians
safe from the steep slope that drops off to the river and also to provide some erosion control.
54
Figure 44: Part of solution D with the asphalt pavement and fence pictured.
The rest of solution D includes more wooden fencing that follows the slope’s edge, a
continuation of the asphalt pavement, and an area for possible signage to relay the important
historical information about the Ice Pond to pedestrians.
Figure 45: Solution D with less steep asphalt pavement, a wooden fence along the slope’s edge,
and a possible area for signage indicating the historical importance of the Ice Pond.
55
The rendering below is the path nearing the approach of the bridge. Notice the two foot shoulder
on either side of the path as well as the signage that clearly marks which way is for the bridge
and which way is for other path activities.
Figure 46: Path (width of 10 ft.) near bridge approach.
56
Continuing along to the bridge itself, the following image shows a view looking down the
decking of the bridge.
Figure 47: Front view of the bridge.
An important part of this final deliverable section is a discussion on design verification. In a
typical civil engineering project, most of the design verification would be part of later phases but
before construction. For the conceptual phase this project is working in, most of the verification
happened in the form of the drawings and rendering that were created. Looking at the specific
path design requirements in the Traceability Matrix in Appendix B, all of these were verified by
dimensions included in the drawings. For the three specific design requirements for the bridge,
all of these were verified by considering them when doing the structural analysis of the bridge.
57
Figure 48: Traceability matrix with path and bridge requirements and verifications sources
shown.
7. Cost Analysis
An initial cost estimate was created using resources available to the group. A second, higher set
of estimates were established from a conversation with our liaison Wayne Feiden. A breakdown
of the group’s initial cost estimate is in Figure 49.
58
Figure 49: An estimate of the initial estimated cost of the shared use path, bridge, and total cost
of the project.
Since this project is only a conceptual design, not all factors were priced. The cost for the shared
use path is roughly $680k. To account for future changes in pricing and miscellanea, a 25%
contingency is added to this cost, bringing it to $850k. Similarly, since the bridge is $1.06M, a
25% contingency added to it brings the cost of the bridge to about $1.4M. The total costs the
team estimated are near $2.1M, which were rounded conservatively to $2.5M. More details on
how these prices and quantities were estimated are in Appendix R.
59
Liaison Wayne Feiden provided rough estimates from his experience as a city planner for the
cost of these types of projects. His estimates were higher than what the group estimated.
Table 11: Initial and Final Estimated Costs for the Northampton State Hospital Shared Use Path
project.
Initial Estimated Cost Final Estimated Cost
Path $850k $1-2m
Bridge $1.4m $1.5-2m
TOTAL (Rounded) $2.5m $2.5-4m
This demonstrates that the project is feasible to complete within the projected $4m budget.
8. Future Implementation
A significant amount of work was completed for this project over the course of the academic
year, yet this work only covers about 10% of the entire civil design process. Moving forward, the
next steps would be to move into the design development phase, or reaching the 25% mark. A
significant amount of time goes into preparing for construction documentation, or reaching the
75% mark. The last stage is the construction process. Additional next steps include presenting
this work to legislators and using it for grants. Both of these steps are part of the process for
applying for funding for the project.
At this point, there are additional tasks to be completed but due to time and access they are
unable to be completed this year. The first suggestion is to conduct a geotechnical analysis of the
footing location near the Wireworks factory. Assuming that side of the river we completed field
work on has a similar soil profile as the other side near Wireworks is a large assumption in this
project. Performing another geotechnical analysis of this side would narrow down or completely
eliminate this assumption. The team recognizes the next geotechnical field work that would be
completed in the future would also be much more comprehensive than the tests we were able to
complete and we anticipate this work done by certified engineers and technicians. An additional
recommendation is for another investigation of the drainage and erosion issues near or on the
path. These two issues were not the central design challenges of this project, which meant these
concerns were only addressed at a general level. The bridge would benefit from higher-resolution
analyses. The next phase of structural analysis would be to analyze the bridge for horizontal
loading conditions such as wind. Since these horizontal loads were not included in the team’s
analysis, the superstructure was built conservatively, so a more thorough study could potentially
refine the bridge dimensions to get the light and airy look NOPS and MRGI would like.
Addressing these next steps would lead to a more detailed path and bridge design proposal and
more accurate visuals. It would also be good to formally analyze the bridge’s resistance to the
100- and 500-year flood events. This would involve calculating the freeboard space between the
60
bridge and the water level for each flood, modeling the forces placed on the bridge, and
estimating the bridge’s resistance to scour.
9. Summary
The history of the Northampton State Hospital and the Wireworks Factory’s revolutionary
importance was researched early on in this project. The site history situated the project space and
provided a clear understanding as to why the Mill River Greenway Initiative wanted to convey
the importance of the land to the people of the Pioneer Valley.
Design requirements were extrapolated from the research done to satisfy the needs of the project
and the stakeholders alike. With the aid of stakeholders, NOPS and MRGI, the necessary
regulations needed to be considered when building the bridge and the path were made clear; one
of these regulations being that this area contains wetlands and other natural habitats that are
protected under law and should, thus, not be touched. These spaces, along with their
corresponding regulation, are necessary components of the design process. They are
subsequently used as constraints during the permitting process that is to be implemented near the
construction phase of the project.
Another major component used to determine next steps of the conceptual design requirements
was increasing familiarity with the geology of the region. Analysis of regional soil near the
proposed abutment location for the bridge confirmed data readily available on ArcGIS about the
composition of the soil. It was concluded that the region contains cohesionless, granular soil
which indicates moderate drainage in the area. This soil information was used to further aid in
the design of the abutment foundations. Moreover, elevation profiles were used to visualize any
regions were a concern when it came to grading compliance of the path. The elevation models in
tandem with the data compiled on soil in the region provided a basis to continue the conceptual
design of the path and bridge.
A preliminary structural analysis was completed for the conceptual design that included the most
pertinent loads that are pedestrian, vehicular, and dead loads. This work helped narrow down
steel member sizes and eventually lead to a finite element model that showed that there were no
structural issues with the current conceptual design.
Lastly, final visualizations for path solutions and bridge concepts were created to reflect design
requirements. Some of these visuals were used in a legislative presentation that could be shown
to local government officials and other funding agencies to provide a general idea of feasibility
and benefit to the community.
Appendix A: Gantt Chart
Design Clinic 2020-2021
PROJECT TITLE DC-NOPS/MRGI COMPANY NAME Design Clinic
PROJECT MANAGER Q1: Ruth Penberthy Q2: Karena Garcia Q3: Christian Madrigal Q4: Barb Garrison DATE 4/30/21
SHEET PURPOSE Track work progress throughout the academic year.
Quarter Project Tasks / Deliverables TASK OWNER START DATE DUE DATE Task Status
Quarter 1 Quarter 2 J-Term Quarter 3 Quarter 4
9/21 9/28 10/5 10/12 10/19 10/26 11/2 11/9 11/16 11/23 11/30 12/7 12/14 1/4 1/11 1/18 1/25 2/1 2/8 2/15 2/22 3/1 3/8 3/15 3/22 3/29 4/5 4/12/21 4/19/21 4/26/21 5/3/21 5/10/21
M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F M T W R F
1 Q1 Presentation Q1 Report
Objective 1 Collect historical data 9/17/20 Completed
Obj. 1 Task-Independent historical overview research Barb
Obj. 1 Task-Speak to John Sinton for area history
overview Barb
Obj. 1 Task-Gather info from Gaby for second opinion Barb
Objective 2
Conduct research on path and
bridge guidelines and
regulations
9/17/20 Completed
Obj. 2 Task-locate necessary permits, organize into
table Karena
Obj. 2 Task-AASHTO Research Barb
Obj. 2 Task-Bridge Legislation Research Christian
Obj. 2 Task-Wetlands Preservation Research Karena
Objective 3 Formulate questions and areas of
concern to prepare for Q2/Q3 work 9/17/20 Completed
Obj. 3 Task- Compile into Doc Group
Obj. 3 Task-
Deliverable 1 Trail/Bridge Site History: Map
Layer 9/22/20 10/16 (Aim
for 10/14)Completed
Del. 1 Task- GIS layer with important sites marked Barb
Del. 1 Task-
Deliverable 2 Trail/Bridge Technical Background:
Map Layer 9/30/20 10/16 (Aim
for 10/14)Completed
Del. 2 Task- GIS layer with soil Issues marked Christian
Del. 2 Task- GIS layer with river Issues marked Christian
Del. 2 Task- GIS layer other technical issues marked Ruth
Deliverable 3 Presentation (Presentation Slides)Ruth 10/8/20 10/16 (Aim
for 10/14)Completed
Deliverable 4 Team Q1 Report 10/13/20 10/23 (Aim
for 10/21)Completed
Quarter Project Tasks / Deliverables TASK OWNER START DATE DUE DATE Task Status
2
Objective 1 Geotechnical Analyses Completed Q2 Report Draft Q2 Presentation
Obj. 1 Task-
Determine which two geotechnical
analyses should happen in Q2: scour,
bearing, settlement, retaining
Group 10/24/20 10/26/20
Obj. 1 Task-Geotech 101 subject learning Group 10/24/20 11/14/20 THXGVN BREAK
Obj. 1 Task-Determine what geotechnical tests can be
done in the field Group 10/23/20 10/25/20
Obj. 1 Task-Determine what variables are needed to
make bridge and abutment decisions Group 10/24/20 11/14/20
Obj. 1 Task-Meet with Professor Rubin for guidance on
all of the above Group 10/27/20 10/27/20
Obj. 1 Task-Carry out the tests decided upon Ruth 11/14/20 11/14/20
Objective 2 AutoCAD-Civil 3D Completed
Obj. 2 Task-
Make sure everyone has access to the
software whether remote or local Group THXGVN BREAK
Objective 3 Bridge Research Completed
Obj. 3 Task-Research types of bridges in general Karena 11/12/20 11/14/20
Obj. 3 Task-Research selected bridge type (Truss)Karena 11/15/20 11/21/20
Obj. 3 Task-
Research decking material (wood, steel,
FRP, concrete)Karena 11/12/20 11/21/20 THXGVN BREAK
Obj. 3 Task-
Create a matrix to compare the research
results Group 11/21/20 11/21/20
Obj. 3 Task-
Select 3-5 bridge options to move forward
with Group 11/23/20 11/23/20
Obj. 3 Task-
Justify the 3-5 bridge options in a write up
that can go into the report and Q2 memo Karena 11/21/20 11/30/20
Obj. 3 Task-Add to the options to the report Karena 11/21/20 11/30/20
Objective 4 Path Completed
Obj. 4 Task-Point out the path's steepness issues
Christian and
Barb 11/18/20
Obj. 4 Task-
Determine how best to categorize the
troublesome sections
Christian and
Barb 11/19/20 11/23/20
Obj. 4 Task-
Clean up graph of trouble sections to
present
Christian and
Barb 11/20/20 11/30/20
Obj. 4 Task-
Write up path solutions (cut+fill,
switchbacks, reroute
Christian and
Barb 11/30/20
Deliverable 1 Q2 Report Completed
Del. 1 Task-Implement Wayne's comments Karena 10/26/20 11/19/20
Del. 1 Task-Implement Gaby's comments Karena 11/19/20 11/19/20
Del. 1 Task-Implement Professor Rubin's comments Karena 11/3/20 11/5/20
Del. 1 Task-Update Table of Contents Karena 11/12/20 11/14/20
Del. 1 Task-Submit Draft for Review Group 11/30/20
Del. 1 Task-Make necessary edits and submit for
grading Group
Deliverable 2 Q2 Presentation
Del. 2 Task-Create presentation deck Karena 11/12/20 11/12/20
Del. 2 Task-Add slides about bridge selection
Del. 2 Task-Add slides about path
Quarter Project Tasks / Deliverables TASK OWNER START DATE DUE DATE Task Status
J-Term:
Objective 1 Geotechnical Engineering Completed
Obj. 1 Task
Perform Geotechnical Lab tests on site
samples if Professor Rubin/Ford is
available
Group 1/20/21 1/21/21
Obj. 2 Task Analyze Geotechnical Results Ruth, Karena 1/21/20 2/10/21
Objective 2 CAD Drafting Completed
Obj. 2 Task Define bridge site in AutoCAD Karena 1/4/21 1/15/21
Obj. 2 Task Define path site in AutoCAD Karena 1/4/21 1/15/21
Obj. 2. Task Work on modeling bridge structure in
Fusion 360 Karena 1/19/21 1/29/21
Objective 3 Bridge Loading Completed
Obj. 3 Task Define assumptions regarding loading Barb 1/18/21 2/15/21
Obj. 3. Task Begin bridge loading calculations Barb, Karena 1/18/21 2/15/21
Deliverable 1
CAD Drafts of Path-Bridge
Connection and Bridge
Structure Completed
Del. 1 Task AutoCAD Drawing of Path and Bridge Karena 1/4/21 1/15/21
Del. 2 Task
Fusion 360 Scaled model of the Bridge
Structure Karena 1/19/21 1/29/21
Quarter Project Tasks / Deliverables TASK OWNER START DATE DUE DATE Task Status
3
Objective 1 Refine Geotechnical
Calculations Completed
Obj. 1 Task Complete any geotechnical lab tests that
were not completed over J-Term Ruth 2/16/21 2/23/21
Objective 2 Begin Abutment/Footing
Design Completed
Obj. 2 Task Define Assumptions for the footing design Ruth, Karena 2/23/21 2/26/21
Obj. 2 Task Retaining Wall Calculations Ruth, Karena 2/26/21 3/3/21
Obj. 2 Task Footing/abutment bearing capacity Ruth, Karena 2/26/21 3/1/21
Obj. 2 Task Footing/abutment sizing Ruth, Karena 3/1/21 3/12/21
Obj. 2 Task Determine footing /abutment contact
pressure Ruth, Karena 3/1/21 3/3/21
Obj. 2 Task Determine significance of relevant factors
of safety Ruth, Karena 3/8/21 3/10/21
Objective 3 Structural Analysis Completed
Obj. 3 Task Compile list of loads to be considered Barb 2/17/21 2/24/21
Obj. 3 Task From the list of loads, come up with
reasonable values in Newtons or psf Barb 2/24/21 2/26/21
Obj. 3 Task Create a shear and moment diagram Barb 3/3/21 3/5/21
Obj. 3 Task Understand which members would be in
tension or compression in all bridge option Christian, Barb 3/8/21 3/10/21
Obj. 3 Task Sizing the truss members accordingly 3/17/21 3/24/21
Objective 5 PR Package Completed
Obj. 5 Task Complete cartoon set for local
stakeholders Group 3/1/21 Q4
Objective 6 Path Grading and Drainage Completed
Obj. 6 Task Walk the path in person as a team
hopefully Group 2/28/21 3/29/21
Obj. 6 Task Identify areas of grading and drainage
concern in person.Group 2/28/21 3/3/21
Obj. 6 Task
Make sure that these spots correspond to
the data and graphs we made in Q2
(Validation protocol)
Christian 2/28/21 3/1/21
Obj. 6 Task
Use the GPS Logger to create two or three
possible routes to resolve grading issues
as the path currently exists.
Christian,
Karena, Ruth 3/3/21 3/10/21
Obj. 6 Task Collect data on the entire path to ensure
accurate path/trail
Christian,
Karena 3/10/21 3/10/21
Obj. 6 Task analyze the whole path elevation to check
for areas of concern Christian 3/10/21 3/19/21
Obj. 6 Task determine candidate locations for cut and
fill and identify amount of needed cut/fill Christian 3/19/21 3/19/21
Deliverable 1 Project Visuals Completed
Del. 1 Task Bridge superstructure visuals Karena 3/1/21 Q4
Del. 1 Task Path design visuals Karena 3/1/21 Q4
Deliverable 2 Cartoon Set for Stakeholders Completed
Del. 2 Task Put together a rough draft for comment Group 3/1/21 3/17/21
Quarter Project Tasks / Deliverables TASK OWNER START DATE DUE DATE Task Status
4
Objective 1 Ecological Impacts Completed
Obj. Task 1 Create a general ecological impact write
up Christian 4/14/21 4/26/21
Objective 2 Cost Analysis Completed
Obj. 2 Task Compile prices and quanitites for a
preliminary cost estimate Ruth, Karena 4/16/21 4/27/21
Deliverable 1 REVISION C Report Completed
Del. 1 Task All hands on deck for edits from feedback Group 4/23/2021 4/30/21
Deliverable 2 Q2 Presentation Completed
Del. 2 Task-Create presentation deck 4/23/21 5/5/21
Del. 2 Task-Add slides about bridge selection 4/23/21 5/5/21
Del. 2 Task-Add slides about path 4/23/21 5/5/21
Del. 2 Task-Practice, Adjust, Present 5/5/21 5/5/21
Deliverable 3 Cartoon Set for Stakeholders
Continued Completed
Del. 2 Task Finalize based on feedback Group 4/20/21 5/14/21
Appendix B: Traceability Matrix
TRACEABILITY
MATRIX
NOPS/MRGI Date:4/29/2021
Ruth Penberthy, Karena Garcia, Christian Madrigal, Barb Garrison Revision:C1
The Norhampton Office of Planning and Sustainability and Mill River Greenway Initiative are hoping to build a bridge to cross from the corn fields down from Commuity Gardens to Federal
Street. In adddition, they are hoping to make the existing trail more accessible by paving it and ensuring that it follows state and federal trail accessibility guidelines.
Design Requirements (DRs)
Path or Bridge Stakeholder Need Statement DR ID Design Requirement Statement
Design
Requirement
Specification Design Requirement Source
Verification Protocol for
DR
Path
MassDOT will not fund a trail that has a
grade greater than 5%. DR-01 Grading should not exceed 4.5%.Grading < 4.5%
11.3 Accessibility of Shared-Use Path,
MassDOT Mass Highway (2006). https:
//www.mass.
gov/files/documents/2016/08/nq/ch-
11.pdf
AutoCAD and GIS Data
MassDOT will not fund a trail that is not at
least 10' wide or 8' if absolutely necessary.DR-02 The path should be at least 10' wide.Width = 10'
11.4.1.1 Path Width, Shared Use Paths
and Greenways, MassDOT Mass
Highway (2006). https://www.mass.
gov/files/documents/2016/08/nq/ch-
11.pdf
AutoCAD and Conceptual
Drawings are drawn with 10'
wide path
The trail must be accessible to those that
fall under the American Disabilities Act
(ADA)
DR-03 The trail should be an asphalt paved, 10'
wide trail.
Width = 10'
Material = Asphalt
MassDOT Mass Highway (2006). https:
//www.mass.
gov/files/documents/2016/08/nq/ch-
11.pdf
AutoCAD and Conceptual
Drawings are drawn with 10'
wide path
The trail should provide stopping and
resting areas off the path, allow for snow
storage, help to prevent root damage, and
to allow passing and widening at curves
DR-04 The trails shold have shoulders at least 2-
feet wide Shoulders = 2 ft
11.4 Shared Use Path Design, MassDOT
Mass Highway (2006). https://www.
mass.
gov/files/documents/2016/08/nq/ch-
11.pdf
AutoCAD and Conceptual
Drawings are drawn with 10'
wide path
Bikers and pededstrians along the trail
should have a clear path without
obstructions near their head.
DR-05 The trail should have a vertical clearance
of at least 8 ft.
Vertical clearance =
8ft 11.4.1. 3 Vertical Clearance
AutoCAD and Conceptual
Drawings are drawn with 8'
vertical clearance
The trail should not have drainage issues.DR-06 The trail should have a maximum cross
slope of 2%Cross Slope <= 2%
11.4.14 Drainage, MassDOT Mass
Highway (2006). https://www.mass.
gov/files/documents/2016/08/nq/ch-
11.pdf
AutoCAD and Conceptual
Drawings
Bridge
The bridge needs to be able to withstand
pedestrian traffic.DR-07
Pedestrian bridges shall be designed for
an evenly distributed live
load of 90 pounds per square foot .LL = 85psf
AASHTO Guide Specification for the
Design of Pedestrian Bridges Structural Analysis
The bridge needs to be able to withstand
an emergency vehicle DR-08
Bridges will be designed to withstand a
moving vehicle load which weighs 1000
pounds per foot of width (up to 10,000
pounds) of bridge. This concentrated load
is in addition to a 20 pounds per square
foot evenly distributed live load. The
vehicle load shall be distributed such that
80% of the load is on the rear axle.H-10 Loading
AASHTO Guide Specification for the
Design of Pedestrian Bridges Structural Analysis
The bridge should have safety railing.DR-09
The bridge must have a minimum of 3ft 6
in railing on either side It must also have
a rub rail at least 3 ft from grade.
Railing >= 3' 6" Rub
rail >= 3"
VTrans Pedestrian Pedestrian and
Bicycle Facility Planning and Design
Manual Conceptual Design
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Appendix C: Stakeholder and Design Requirement Development
This section explains our stakeholders and their needs in greater detail than the body of the
report.
Appendix C1: Stakeholder Development
Appendix C1.1: Northampton Office of Planning and Sustainability
The Northampton Office of Planning and Sustainability (NOPS) is one of the major stakeholders
of this proposed public works project. NOPS needs the design of both the shared use path and the
bridge abutment foundation to not encroach on the existing agricultural land. This constraint is
part of their long term goal of filing the legislation for easements for the project and also allows
them to reach a consensus with the Massachusetts Department of Agricultural Resources and the
Smith Vocational Agricultural High School. In the same vein, this limitation overlaps with
NOPS’s need of minimizing the bridge abutment and foundation footprint in the local ecosystem.
Both of these needs determine the project's capacity to receive funding, as MassDOT will not
fund projects that infringe on wetlands and disruptive activities in sensitive areas.
NOPS not only requires that the path meet all other design requirements outlined by the
Massachusetts Department of Transportation (MassDOT), but also the Americans with
Disabilities Act (ADA) and the City of Northampton. The two major requirements that must be
met have to do with the path width and grading; the width must be 10 feet at a minimum and the
grading can be no steeper than 4.5%. Although the ADA guidelines specify a 5% maximum
grading, MassDOT and the City of Northampton mandate a 4.5% maximum grading to account
for minor errors from contractors. MassDOT will not fund projects with grading higher than
4.5% (and even then a 8% maximum) unless it is proven that there is either no other alternatives
present to circumvent that, or the area in question is part of a cliff, wetland, or archaeological
site.
It is important that the cost of the project is reasonable and justifiable. The estimated budget for
this project is about $4 million dollars, however, according to NOPS, this is not necessarily a cap
as compromises on design solely to fall within budget should be avoided. This will require a cost
estimate to confirm that all aspects of the project are appropriately accounted for given the
project’s scope and estimated budget constraints.
Another need outlined by the stakeholder includes vehicular access for emergencies. As a result
of this explicit need, other necessary structural standards and guidelines will inform the design
and performance of the structure abutment foundation.
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Appendix C1.2 Mill River Greenway Initiative
Alongside NOPS, the Mill River Greenway Initiative is another central stakeholder that uplifts a
complimentary set of community needs. Encapsulating the river’s history is part of MRGI’s
broader mission to reshape community identity around the river, which was central to the success
of the city during earlier stages of its development. Promoting the benefits of the bridge with a
coherent narrative will gauge and galvanize community support which will be essential in
facilitating local and state-wide funding for the project. Understanding the context in which the
project is taking place also informs the process of construction, as important historical sites must
be preserved to ensure that the mission of MRGI is upheld. Preservation of historical sites along
with the wonderful scenery can also encourage recognition from the Conservation Commision
that can move forward with legitimizing it as part of their Greenway Network.
Appendix C1.3 Northampton Community
Community engagement with the river is one of the major objectives of this proposed public
works project, and therefore another primary stakeholder is the greater Northampton community.
Both the proposed bridge and path should be easily accessible, providing all patrons with the
capacity to engage with the space. This in turn will also confirm that any monetary investments
are valuable. The proposed project promotes alternative transportation modes that provide access
to Northampton High School for commuters in the community as well as handicap accessibility.
Safety is of paramount importance for this project given that the bridge and path are expected to
function through all seasons and for a range of user ages and abilities. The appropriate materials
should be selected to ensure that the bridge does not sustain any cracking as a result of any
freeze-thaw that is expected to occur with other materials. This need overlaps with structural
needs of NOPS as maintenance costs of the bridge influence budget planning. It is also important
to recall that a certain percentage of the local community will cycle on this path, and therefore
the cusp that connects the bridge and the path should be gradual and smooth. This contributes to
safety aspects as the cyclist population is not exposed to potential injury and limits the capacity
for serious pedestrian and cyclist accidents. As described, there are sub communities that exist
within the broader Northampton community, as seen with the cyclists and dog walkers, and
therefore consideration of those as stakeholders will include people that engage the area
regularly.
Appendix C1.4: Local Environment
Another stakeholder central to the design consideration that will be explored within this project
is the local ecology, defined as the river, soil, flora and fauna in the region. Delineating the local
ecological needs will inform an optimal design and implementation of the project. One of the
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major needs is making sure that scour during time of construction is minimized to prevent water
quality degradation. Although scour control is more closely monitored during the project
implementation stage, the conceptual design process and suggested abutment design should
consider and minimize sources of potential scour. Moreover, the local environment requires
appropriate drainage mechanisms to exist as part of both the bridge and the path. Proper drainage
plans for the site location that consider the Mill River floodplain may address erosion, potentially
reduce erosion rates and/or prevent topsoil damage.
Appendix C2 Design Requirement Development
This appendix explains in more detail where some of our design requirements came from. A
significant portion of quarter one was spent working to understand the engineering processes,
laws, and other guidelines that would impact the bridge and trail designs. The relevant portions
of these regulations and their impact on the design requirements are listed below.
Appendix C2.1 Trail Accessibility Guidelines
Beginning at the federal level, most of the guidelines are specifically tailored to National Parks.
Although this area of trail is not part of a National Park, and hence, not legally bound to the
guidelines outlined in the United States Forest Service Trail Accessibility Guidelines, it is still
important to consider the rules and regulations at the federal level as this project is receiving
funding from the federal government, not to mention the FSTAG provide reasonable technical
provisions.
The main two guidelines to consider for trail accessibility are its surface and slope, especially
when it comes to paved surfaces. When it comes to the trail’s surface, the only provision the
FSTAG notes is that it must be “both firm and stable.” Since this trail will be paved, this
guideline is not terribly concerning because there is no question as to whether asphalt is
considered firm and stable. Should the paved surface have any openings, however, those
openings should be no larger than ½” or, in extenuating circumstances, ¾”. In addition, obstacles
on the surface can be no larger than ½”. Shifting focus towards slope, for any distance of a trail,
the slope cannot exceed 5%. If there is no way to achieve that slope percentage, there are
exceptions that allow some parts of the trail to be no greater than 8.33%, or if absolutely
necessary, 12%. With each slope comes regulations on resting intervals that increase in
frequency as the slope steepens. This information is summarized nicely in Table C2 below from
the 2015 FSTAG Pocket Version.
It should also be noted that section 7.4.3.2 of FSTAG states if a trail is going to be paved or
elevated above the natural ground, the cross slope (slope perpendicular to the direction) cannot
exceed 2%. The FSTAG provides a quick reference flow chart that can help determine what
technical provisions should be considered which is referenced in Tables C3.1 and C3.2.
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Shifting focus to the state level, similar to how the federal level pertains to National Parks, state
guidelines are heavily focused on State Parks. These guidelines are implemented and upheld at
the state level by the Massachusetts Department of Conservation and Recreation (DCR). The
DCR was created after a merger of two agencies was enacted, so there were different state-wide
policies being followed from trail to trail. Now, with the DCR as the sole governing body behind
state trails, they created the Trail Guidelines and Best Practices Manual. According to this
manual, the DCR has adopted the same technical provisions outlined by the FSTAG. However,
unlike the FSTAG, the DCR’s manual emphasizes the sustainability of an existing or proposed
trail in the Commonwealth. Specifically, the manual says that sustainable trails should
“...connect positive16, and avoid negative, control points, keep water off the trail, follow natural
contours, keep users on the trail, and meet desired user experiences.” A brief description of each
of these guidelines is provided in Figure C4. Moreover, the DCR provides more insight on how
to design a sustainable contour trail with five technical specifications. These five specifications
were taken directly from the DCR Trail Guidelines and Best Practices Manual’s section titled
“Building Sustainable Trails” and placed in the Design Requirements section of this report.
In addition to the technical side of trail building, the best practices manual touches on the softer
side of trail design such as managing trail viewsheds, shapes, and landscape features as well. The
DCR notes that viewsheds should spotlight the most scenic parts of the trail and down play the
less attractive parts as to enhance the user’s experiences while using it. Shapes of the trail should
vary from different sized loops to spurs to long flat areas and even more sloped areas.These trails
should also have clear starting and ending points as well as clear destination points to leave the
user feeling oriented and ultimately accomplished after their trail experience.
Trail features like gateways, anchors, and edges can help tie the connection between the trail
itself and the natural environment around it. Gateways can be man made, like with a physical art
piece transitioning one part of the path to another, or occur naturally, like when dense tree
coverage opens up to a meadow. Both make for a more intimate setting between the trail, the
environment, and the user. Anchors may include a large boulder or a distinguished tree, but it
can be any vertical object along the trail.
At the state and local levels, most of the guidelines work in parallel because rules and regulations
the local government have to follow come from the state. In this case, Northampton and the
surrounding cities must abide by the laws of the Commonwealth of Massachusetts. When it
comes to the proposed trail and bridge implementation, the most notable guidelines found at the
local level are more permitting based than accessibility based because the local government’s
accessibility guidelines do not deviate from the state’s accessibility guidelines.
16 https://www.mass.gov/doc/dcr-trails-guidelines-and-best-practices-manual/download Last Accessed 10/21/20
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Table C1: Matrix of resources to reference when considering trail accessibility guidelines at the
federal and state levels.
Level Link Description
Federal https://www.fs.usda.gov/managing-
land/trails/trail-management-
tools/trailplans
Provides a step-by-step process on
how to get a trail built on a
NATIONAL Forest. Has bridge
drawing and abutment examples.
Federal Forest Service Trail Accessibility
Guidelines (FSTAG) Pocket
Version
Pocket Version of the FSTAG
Federal Trail Construction and Maintenance
Notebook: 2007 Edition
Book of How-Tos. Bridge Section.
No abutment details.
State Trails Program Gives technical specifications for
trails and steps to take if in a
sensitive area.
State https://www.mass.gov/files/docume
nts/2016/08/qq/management-
guidelines.pdf?_ga=2.175076961.2
37079820.1600399520-
1562146276.1600399520
Classifies the type of trail. Explains
why it’s classified as that and how to
treat it as such and what things go
along with that distinction. Provides
maps to help prove that we are not
State Park Property.
State Wetland and Wetland Change
Areas Map
Wetland Map Viewer.
State Regulatory Maps: Priority &
Estimated Habitats
Protected Habitat Area Map Viewer
71
Table C2: A summary of technical provisions for trails from the United States FSTAG Pocket
Version.
Figure C3.1: The FSTAG Quick Reference flow diagram that helps determine whether
the FSTAG applies to a project and next steps.
72
Figure C3.2: A continuation of Figure C3.1, specifically looking at Steps 3 and 4 in the
decision making process.
73
Figure C4: Softer technical provisions from the DCR best practices manual that should be
considered when designing a sustainable trail system.
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Appendix D: Site Visit Photos
Appendix D1: February 28th 2021
Top: Ice Pond looking up the slope. Bottom: left side slope at proposed bridge site.
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Top: River crossing at proposed bridge site. Bottom: Side view of river crossing at proposed
bridge site.
76
Wireworks side of proposed bridge site slope, looking up.
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Appendix D2: March 6th, 2021
Top: Slope issue after the drainage concern. Bottom: Possible stairs option near Village Hill.
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Level front view of the river crossing at the proposed bridge site.
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Appendix D3 March 10th, 2021
Left: Slope concern before the drainage concern. Right: Existing infrastructure near the Ice
Pond area.
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Appendix D4: March 22nd, 2021
Top: Side view of slope concern near Village Hill. Bottom: Side view of slope concern before
drainage issue.
81
Top: Slope concern near the ice pond. Bottom: Ice Pond.
82
Appendix D5: March 29th, 2021
Left: Erosion concern near the Ice Pond. Right: Bridge approach.
83
Top: River cross section with person for scale. Bottom: River cross section looking downstream
toward proposed bridge site.
84
Appendix E: Preliminary Path Slope and Grading Analysis
Figure E1: The path file used to generate slope data, marked with approximate distance from
beginning of path.
Our path is about 2000 meters long. The analysis took the beginning of the path to be the bridge
and the end to be its contact with the path network near Hospital Hill. The group split the path
into four sections - A, B, C, and D - of 500m each. The split makes it easier to understand where
slope problems are located. It was confirmed that 500m, 1000m, and 1500m are all flat, and
therefore we are not splitting a problem spot down the middle of two sections. Discussions with
our liaisons revealed that Section D is going to change. We will present our findings for the
layout of Section D that we were initially given.
Appendix E1: Problem Statement
The path must comply with the Americans with Disabilities Act, which requires a maximum
grade of 5%. The purpose of the analysis was to identify regions of the path that are too steep,
and therefore, do not comply with ADA regulations. Along the path, grade is allowed to increase
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the 4.5% minimum to 8% over short stretches of path if a 5% grade is impossible. To ensure that
the project maximizes accessibility over the entire span of the path, a maximum grade of 4.5% is
the goal to ensure absolute compliance.
Appendix E2: Methods
Using ArcGIS along with an elevation model, data on the elevation of the profile was extracted
which would allow us to perform a slope assessment. It is important to note that the data used for
this assessment used data points that were perhaps located on contour lines that were placed at
1m intervals. Given that the elevation profile of the path was exported from ArcGIS into a
comma separated file, the initial analysis required we order the arbitrary outlined paths into the
path that would be followed by a pedestrian from the proposed bridge site to the hospital hill site.
Moving forward slope and then grade was calculated using the functions available in the
Microsoft Excel software to produce an initial visualization of the grade variation along the path.
This initial graph detailed noisy data that did not facilitate in identifying any true regions of
concern along the path. To refine the number of potential problem regions the team calculated an
average grade of every 40 meters along the path. This graph was used as a tool to visually
pinpoint regions of concern which would then need to be addressed to ensure ADA compliance.
The team further annotated the provided graphs and decided that tackling sections of the path
would be best. Therefore, moving forward the team sectioned off the path into four equal
sections to address regions with higher grade percentages.
Moving forward in the process to address any regions of concern, the team was advised to
understand how averaging across certain sections of the path with respect to cohesive slope
might make regions of concern more obvious. The process required averaging the grades along
the sections that were suggested by Professor Aaron Rubin. These estimates were graphed along
the average distance of that path section and these data are seen clearly in Figure E2.
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Figure E2: Annotation of what sections along the path provide visual cohesion to be used for
averaging of slope. These annotations were provided as rough visual suggestions by Professor
Aaron Rubin.
87
Appendix E3: Results and Discussion
Figure E3: Team annotated graph for the 8-point average of slope for the path as one moves
from the proposed bridge site towards hospital hill. This graph also details the four major regions
of concern that informed which way the path was to be sectioned off.
In Figure E3, elevation and average slope are graphed against distance along the path. Problem
spots are highlighted in cyan and labeled A, B, C and D. (Different from section labels A, B, C,
D) The data are noisy, and the path we got this slope data from is not the current version of the
path - Section D on Hospital Hill is different now. Since we have larger-level changes to make,
the group will only explain and attempt to address the most obvious problem spots by proposing
cut and fill, switchback, or rerouting as a solution to achieve grading compliance.
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Figure E4: Graph of the entire path elevation profile along with the grade percentages as the
path distance changes. This figure depicts the four sections that were chosen to further the
problem region analysis. The first section ends at the 500 meter mark, the second at 1000 meters,
the third at 1500 meter, and the fourth at the end of the path. These sections were labeled A, B,
C, and D respectively.
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Appendix E3.1: Section A
Figure E5: Section A
Section A has a clear problem area at the very beginning of the path which begins on Federal
Street instead of its actual beginning on the Mill River. There is a strong belief that the data that
was extracted from ArcGIS may have some inconsistencies that may provide inaccurate
information at the site.
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Appendix E3.2: Section B
Figure E6: Section B of the path.
Section B has one potential problem region that might be located near the agricultural fields.
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Appendix E3.3 Section C
Figure E7: Section C of the path
As of now the section labeled Section C includes Hospital Hill. This section seems to be the most
problematic but given that much of this section path does not exist the team will refrain from
further analysis.
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Appendix E3.4 Section D
Figure E8: Section D
Section D is currently the end of the path section that is no longer part of the proposed shared use
path that will be paved. This section will change when the appropriate LiDAR data is extracted.
Moving forward,Section D at the end of the path will be updated to demonstrate the region
which will be added to be part of the shared use path.
Other Suggested Methods
As briefly explained, the team also decided to conduct visual averaging of the slopes to
understand what this would look like as the previous data were too noisy. This analysis yielded
the following results which may not depict the path accurately but does confirm that the bridge
site location poses a site of concern (Figure E9).
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Figure E9: Graph depicting the elevation profile of the proposed shared use path in meters. This
graph also demonstrates the average of the sections as we move along the path.
Appendix E4: Discussion of Preliminary Analysis
This analysis made use of an embedded digital elevation model (DEM) of the greater
Northampton region and a data layer with the proposed path was used to view elevation changes.
The path was sectioned into four different pieces and an elevation profile for each of the sections
was produced by ArcGIS. Figure E10 depicts one such path that ArcGIS used to calculate and
produce a corresponding elevation profile. Given that the path was partitioned arbitrarily by the
software, to better understand the changes in the elevation, path data was adjusted accordingly
and an entire path elevation profile was produced (Figure E11). Adjustments to the data also
allowed for calculations on grade variation along the path. Specifically, the grade was averaged
for eight different points along the path to reduce the noise produced by a more refined analysis
(process further explained in Appendix F). As seen in Figure E11, grade varied substantially in
a few areas along the path.
94
Figure E10: Map depicting the elevation of the region surrounding the Mill River near the State
Hospital Site. The section of the path highlighted was partitioned by the ArcGIS software and
analyzed to produce a unique elevation profile.
95
Figure E11: Path elevation profile produced for the highlighted path in Figure 3 which
demonstrates change in meters of elevation as patrons move horizontally away from the starting
point on the highlighted path towards the State Hospital Site. This figure also details the change
in grade percentage as the distance along the path increases. The two lines mark the 4.5% or the -
4.5% grade percentage lines to ease in identification of problem spots.
As seen in the elevation profile output for the entire path, there seems to be a steep incline
occurring from the 1200 meter mark to the 1500 meter mark along the path. In this region there
are grade percentages higher than the permitted 4.5% grade constraint (Figure E11). This region
poses an issue due to this steep elevation that may require considering switchbacks from the path
that may demonstrate a lesser elevation as horizontal distance across the path increases toward
the bridge site. Ideally, the path can be altered to better comply with regulations regarding the
required ADA grading of 4.5-5% grading.
To better identify the regions that do not meet ADA requirements, the region was manually split
into four regions. Previously ArcGIS had arbitrarily chosen the path sections, but manually
adapting the data allowed the team to move from vague problem regions previously identified to
a closer look at particular path locations. This analysis was done by sectioning the path off at
several different meter distances along the path.Each of the individual sections were also graphed
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to take an even closer look at problem regions within the smaller distances in each section. As
seen in Figure E11, there are very few regions where the elevation of the path exceeds the
required 4.5% and all of these regions are towards the beginning of the trail. Identifying these
regions early in the process can help enumerate the number of regions and perhaps inform us
which way might be most cost effective to implement. The other section elevation profiles will
also be further analyzed to closely identify the regions where ADA requirements are violated
(section elevation profiles along with the grading percentages can be found in Appendix F).
Figure E12: Section A is the first 500 meters of the total path depicted Figure 3 and begins at
the bridge site. The figure demonstrates the path elevation profile as well as the variation in
grade percentage as one moves along the path. The black line across the graph is meant to serve
as a limit so if points surpass it they are potential sites of concern as the grading percentage is
higher than the 4.5% allowed.
It was suggested to the team to visually inspect the slope change and manually average regions
with a cohesive slope. This would inform of any more significant regions that might need to be
addressed with priority. Professor Aaron Rubin provided annotations of Figure E11 that served
as the visual basis for this averaging. These annotated cutoff points were then used to produce a
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visual representation of how the path grade varies as one moves from the proposed bridge site to
hospital hill (Figure E12).
Figure E13: Graph depicting the elevation profile of the proposed shared use path in meters.
This graph also demonstrates the average of the sections suggested as we move along the path.
Figure E13 provides a cleaner visual of what the path profile looks like alongside the values for
average grading of several sections. As suggested in the figure, there is only one major spot that
may need to be addressed but there is doubt that this is the only region that might need to be
revisited and designed. Given that the team does not have adequate evidence to conclude that the
path has no other major regions of concern, we will move forward with another method for
sectional analysis.
Appendix E5: Conclusion
Overall, as seen by this analysis of the existing path and available data there are two major
problem spots, these being near the agricultural field as well as the section of path near Hospital
Hill. As of now, other regions along the path have a grade that is lower than the maximum
permitted 5% and while this is not immediately concerning, the team will work on these once the
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most concerning regions have been addressed. Next steps of the path analysis will make use of
available LiDAR data that may confirm any regions of concern and provide an accurate path.
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Appendix F: Refined Path Slope and Grading Analysis
The preliminary analysis of the previous path served as a method to exercise tools that would aid
in refining the approach taken to address any concerns along the proposed shared use path. The
path that was analyzed in Appendix E was an inaccurate analysis of an incorrect path. The
actual path that is intended to be paved as part of this project is seen throughout this report and is
depicted in Figure 1 in the Introduction but is depicted below for reference (Figure F1).
Figure F1: Open street map view of existing trail from the Smith College athletic fields to where
it ends near the abandoned Wireworks factory.
Appendix F1: Problem Statement
The problem statement is the same as stated in Appendix E1 and essentially requires that the
path comply with the Americans with Disabilities Act and maintain a maximum grade of 5%.
For a detailed description refer to the aforementioned appendix section.
Appendix F2: Entire Existing Path Elevation
Appendix F2.1: Methods
The trail profile made use of the GPS Logger Application which collected the data as Karena
Garcia walked the existing trail from the athletic fields towards the bridge site. The GPS data
only extracted data points at arbitrary points along the path and connected them to produce a
continuous line the length of 1750 meters. These data points were then imported into ArcGIS Pro
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as points and lines. Given that the application collected these data under a different geographic
coordinate system, they were projected onto the ArcGIS map into the coordinate system used in
this region of the Americas using the Project Tool in the Geospacing Toolbox of the Analysis
Section in ArcGIS Pro.
Once the path was properly projected into the respective GIS map, the path elevation was
extracted with the use of the Stack Profile Tool. This stack profile tool used the LiDAR data that
was superimposed onto the given GIS map to collect the elevation at each data point in meters.
This data was then presented as a table that was extracted into Microsoft Excel. In Excel, the
data were graphed to demonstrate the variation of the path elevation in an exaggerated scale and
in true scale.
This elevation data offered a great visual representation of the variation in elevation along the
path but did not detail the actual grade in many of the regions. Therefore to better understand the
variation in grade percentage, the grade of 50 meter path sections was calculated as an estimate
of the average grade percentage. To calculate the grade, the slope between two points 50 meters
apart was calculated and then using trigonometry the angle in radians between the slope of the 50
meter section and leveled ground was calculated. This was then converted to degrees which
equates to the grade percentage of that given path segment. A visual representation that was used
alongside the trigonometric relations for this analysis is outlined below (Figure F2).
Figure F2: Demonstrates the change in elevation as Δz from two points with distance along
path, x, and elevation, z both in meters. θ is the angle in radians made by leveled ground and the
slope of the 50 meter segment.
For clarification purposes, a short walkthrough of the calculation of angle θ is shown below: 𝑠𝑠𝑠𝑠𝑠𝑠(𝜃𝜃)=𝛥𝛥𝑧𝑧𝛥𝛥𝛥𝛥
(x2,z2)
(x1,z1)
θ
Δz
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𝜃𝜃=𝑎𝑎𝑠𝑠𝑠𝑠𝑠𝑠(𝛥𝛥𝑧𝑧𝛥𝛥𝛥𝛥)
Appendix F2.2: Results and Discussion
From the analysis done at every 50 meters the team was able to understand the variation of the
grade along the path. The true scale visual that resulted from this analysis is not as informative
and appeared to sustain no grading issues as the path progresses from the athletic fields towards
the bridge site (Figure F3). The true scale path was relatively leveled and therefore to better
visualize the grade variation between these 50 meter segments we have displayed an exaggerated
scale graph (F4).
Figure F3: True scale graph with the left axis displaying the elevation (m) along the distance of
the path in meters from the Smith College athletic fields towards the proposed bridge site. The
right axis depicts the grade percentage as averages across 50 meter segments along the path.
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Figure F4: Exaggerated scale graph with the left axis displaying the elevation (m) along the
distance of the path in meters from the Smith College athletic fields towards the proposed bridge
site. The right axis depicts the grade percentage as averages across 50 meter segments along the
path.
As seen from the two figures above the variation of the path is significant and allowed us to
pinpoint sections of major concern along the path that are summarized in Appendix F3.
Appendix F3: Slope Areas of Concern Analysis and Solutions
Given the analysis that was produced for the entire existing path the tea pinpointed four major
regions of slope concern and single drainage. This section summarizes the analysis of the four
major slope concerns mentioned in section 5.4.6 Shared Use Path Concerns and Solutions and
not the drainage concern. For Area of Concern A, a switchback solution was suggested that is
analyzed herein. Regarding Areas of Concerns B, C, and D, they were suggested as candidates
for cut and fill therefore suggested profiles are also provided.
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Appendix F3.1: Methods
The method of analysis for these path sections made use of data that was collected by Karena
Garcia with the GPS Logger Application. The individual path sections were collected separately
and were analyzed individually. The analyses of the four sections and the switchback suggestion
for Area of Concern A followed the same process outlined in Appendix E2.1 with a few
differences in the sectioning of them. In the process outlined in Appendix E2.1 the entire
existing path was sectioned by every 50 meters whereas these areas of concern and the
switchback suggestion were sectioned off differently to ensure that the average grade estimation
was as accurate as possible. A brief overview of the sections are provide below:
● Area of Concern A: This path segment was 120 meters and was pretty uniform in slope
and was therefore not sectioned off at all. The grade was estimated from a trendline
estimation when the data were graphed.
○ Switchback Suggestion: This segment was 154 meters in length and was broken
into two main sections, 0-80 meters, and 80-154 meters
● Area of Concern B: This path segment was 60 meters in length and was broken into four
main sections, 0-20 meters, 20-40 meters, 40-50 meters, and 50-60 meters
● Area of Concern C:This path segment was 100 meters in length and was broken into five
main sections, 0-20 meters, 20-40 meters, 40-50 meters, 50-65 meters, and 65-100 meters
● Area of Concern D: This path segment was 60 meters in length and was broken into three
main sections, 0-10 meters, 10-40 meters, and 40-60 meters
As for the suggested cut and fill profiles for Area of Concerns B, C, and D the profiles use two
arbitrary data points that were chosen to visually improve the elevation profile of the respective
sites. These two data points were then graphed as a line and the grade for these were also
calculated using the method in Appendix E2.1.
Appendix F3.2: Results and Brief Discussion
Area of Concern A
Using the data collected for this region, the analysis produced an approximate elevation profile
for Area of Concern A that can be seen in true scale in Figure F5.
104
Figure F5: True scale plot of the 120 meter long Area of Concern A. Distance along the segment
is seen in meters as is the elevation along the path segment.
105
Figure F6:. Exaggerated scale plot of the 120 meter long Area of Concern A. Distance along the
segment is seen in meters as is the elevation along the path segment.
To better gauge the variation in elevation, an exaggerated scale plot of Area of Concern A was
produced as seen in Figure F6. As a result of the analysis Area of Concern A was estimated to
have a grade average of 7.64% which was not compliant with the 4.5% ADA grading threshold.
Therefore, this location is a great candidate for a switchback given the severity of the steepness
but should be reassessed when officializing the shared use path. The switchback suggested for
Area of Concern A can is assessed in the next section of this appendix.
Switchback Suggestion
The elevation profile of the suggested switchback for Area of Concern A can be seen in Figure
F7 in true scale, but once again to better visualize the changes in elevation Figure F8 is
provided.
106
Figure F7: True scale plot of the 154 meter long Switchback Suggestion for Area of Concern A.
Distance along the segment is seen in meters as is the elevation along the path segment.
107
Figure F8: Exaggerated scale plot of the 154 meter long Switchback Suggestion for Area of
Concern A. Distance along the segment is seen in meters as is the elevation along the path
segment.
The switchback that was collected as an option to address the steep slope Area of Concern A was
identified to have an estimated grade average of 5.51% which was not compliant with the 4.5%
grading required by ADA. Although the switchback was not below the 4.5% threshold, it still
demonstrated that a switchback solution for this region might address the grading concern. It is
suggested that other switchback options be explored for this site prior to future implementation.
Area of Concern B
Data collected for Area of Concern B was used to produce Figure F9, which is a true scale plot
of the elevation at the site. While this elevation profile is useful, the exaggerated scale plot in
Figure F10 can better display the severity of the slope at this site.
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Figure F9: True scale plot of the 60 meter long Area of Concern B. Distance along the segment
is seen in meters as is the elevation along the path segment.
109
Figure F10: Exaggerated scale plot of the 60 meter long Area of Concern B. Distance along the
segment is seen in meters as is the elevation along the path segment.
Given the collected data for this region, Area of Concern B was identified to have a grade
average of 6.34% which was not compliant with the 4.5% ADA grading. Given that this region’s
average grading was not compliant, it is suggested that cut and fill be used as a means to resolve
this concern. The suggested profile for the cut and fill solution is seen in Figure F11 and would
decrease the estimated grade to 4.06%.
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Figure F11: Exaggerated scale plot of the 60 meter long Area of Concern B profile alongside the
suggested cut and fill profile. Distance along the segment is seen in meters as is the elevation
along the path segment.
Area of Concern C
Data from the region that encompasses Area of Concern C was used to produce Figure F12 and
Figure F13, true scale and exaggerated scale plots, respectively.
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Figure F12: True scale plot of the 100 meter long Area of Concern C. Distance along the
segment is seen in meters as is the elevation along the path segment.
112
Figure F13: Exaggerated scale plot of the 100 meter long Area of Concern C. Distance along the
segment is seen in meters as is the elevation along the path segment.
Using the data, Area of Concern C was identified to have a grade average of 3.65% which was
not compliant with the 4.5% ADA grading. This value might seem compliant but may be skewed
to be portrayed as such. The 10m section that occurs between 40-50 meters in Figure F13 has a
very steep slope of 6.1%. This section combined with the average slope of 4.9% within the 65m
and 100m region seen in Figure F13, are still regions that require further inspection. Overall,
Area of Concern C is a good candidate for cut and fill and the suggested profile for the cut and
fill solution is seen in Figure F14 and would decrease the grade to 3.59%.
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Figure F14: Exaggerated scale plot of the 100 meter long Area of Concern C profile alongside
the suggested cut and fill profile. Distance along the segment is seen in meters as is the elevation
along the path segment.
Area of Concern D
The last segment of the existing path,Area of Concern D, that was analyzed produced a telling
elevation profile seen in true scale in Figure F15 and exaggerated scale in Figure F16.
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Figure F15: True scale plot of the 60 meter long Area of Concern D. Distance along the segment
is seen in meters as is the elevation along the path segment.
115
Figure F16: Exaggerated scale plot of the 60 meter long Area of Concern D. Distance along the
segment is seen in meters as is the elevation along the path segment.
As a result of the analysis, Area of Concern D was identified to have a grade average of 4.77%
which was not compliant with the 4.5% ADA grading. Much Like Areas of Concern B and C,
Area of Concern D is also a good candidate for cut and fill. The suggested cut and fill profile is
seen in Figure F17, this profile visually addresses any abrupt variations in the elevation and
improves the grade to 4.42%.
116
Figure F17: Exaggerated scale plot of the 60 meter long Area of Concern D profile alongside the
suggested cut and fill profile. Distance along the segment is seen in meters as is the elevation
along the path segment.
Appendix F4: Overall Suggestions for Existing Path
It is recommended that the areas of concern discussed be addressed with a combination of cut
and fill and switchbacks. Specifically, for Area of Concern A, a switchback would be
recommended to reduce the existing non compliant grading but cut and fill would also address
this issue. As for the other three areas of concern, B,C, and D, all are great candidates for cut and
fill which could be used to address grading concerns to ensure ADA compliance.
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Appendix G: Geotechnical Literature Review
This appendix is a compilation of the information from a literature review of geotechnical
resources. The fundamental and theoretical work gathered here will be used to analyze the work
done in the field.
Appendix G1: Bearing Capacity
The Following is from Soils and Foundations (Seventh Edition) by Cheng Liu and Jack B. Evett.
Section 9.4, pages 282-287
Bearing capacity refers to the ability of a soil to support or hold up a foundation and
structure. The ultimate bearing capacity (qult) of a soil refers to the loading per unit area that will
just cause shear failure in the soil. The allowable bearing capacity (qa) refers to the loading per
unit area that the soil is able to support without unsafe movement. It is also known as the design
bearing capacity. 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑎𝑎𝐴𝐴𝐴𝐴𝐴𝐴 𝐴𝐴𝐴𝐴𝑎𝑎𝑙𝑙 = (𝑞𝑞𝑎𝑎)(𝐴𝐴𝐴𝐴𝐴𝐴𝑎𝑎 𝐴𝐴𝑜𝑜 𝑐𝑐𝐴𝐴𝑠𝑠𝑐𝑐𝑎𝑎𝑐𝑐𝑐𝑐 𝐴𝐴𝐴𝐴𝑐𝑐𝐴𝐴𝐴𝐴𝐴𝐴𝑠𝑠 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝑎𝑎𝑠𝑠𝑙𝑙 𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴)
(𝑞𝑞𝑎𝑎) = (𝑞𝑞𝑢𝑢𝑢𝑢𝑢𝑢)𝑓𝑓𝑎𝑎𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑓𝑓𝑓𝑓 𝑠𝑠𝑎𝑎𝑓𝑓𝑠𝑠𝑓𝑓𝑠𝑠 (2.5 𝑓𝑓𝑓𝑓 3)
Footings are safely designed by considering possible foundation failures (collapse) or
when excessive settlement might occur. As load (Q) is applied, the footing undergoes a certain
amount of settlement as it is pushed downward, and a wedge of soil directly below the footing’s
base moves downward with the footing. The soil’s downward movement is resisted by shear
resistance of the foundation soil along slip surfaces cde and cfg and by the weight of the soil in
sliding wedges acfg and bcde. For each set of assumed slip surfaces, the corresponding load Q
that would cause failure can be determined. The set of slip surfaces giving the least applied load
Q (that would cause failure ) is the most critical; hence, the soil’s ultimate bearing capacity (qult)
is equal to the least load divided by the footing’s area.
Equation 1: 𝐶𝐶𝐴𝐴𝑠𝑠𝑐𝑐𝑠𝑠𝑠𝑠𝑓𝑓𝐴𝐴𝑓𝑓𝑠𝑠 𝑜𝑜𝐴𝐴𝐴𝐴𝑐𝑐𝑠𝑠𝑠𝑠𝑓𝑓𝑠𝑠 (𝐴𝐴𝑠𝑠𝑙𝑙𝑐𝑐ℎ 𝐵𝐵) = 𝑞𝑞𝑓𝑓𝐴𝐴𝑐𝑐 = 𝑐𝑐𝑁𝑁𝑓𝑓+𝛾𝛾1𝐷𝐷𝑓𝑓𝑁𝑁𝑞𝑞+.5𝛾𝛾2 𝐵𝐵𝑁𝑁𝛾𝛾
Equation 2: 𝐶𝐶𝑠𝑠𝐴𝐴𝑐𝑐𝑓𝑓𝐴𝐴𝑎𝑎𝐴𝐴 𝑜𝑜𝐴𝐴𝐴𝐴𝑐𝑐𝑠𝑠𝑠𝑠𝑓𝑓𝑠𝑠 (𝐴𝐴𝑎𝑎𝑙𝑙𝑠𝑠𝑓𝑓𝑠𝑠 𝑅𝑅) = 𝑞𝑞𝑓𝑓𝐴𝐴𝑐𝑐 = 1.2𝑐𝑐𝑁𝑁𝑓𝑓+𝛾𝛾1 𝐷𝐷𝑓𝑓𝑁𝑁𝑞𝑞+.6𝛾𝛾2𝑅𝑅𝑁𝑁𝛾𝛾
Equation 3: 𝑆𝑆𝑞𝑞𝑓𝑓𝑎𝑎𝐴𝐴𝐴𝐴 𝑜𝑜𝐴𝐴𝐴𝐴𝑐𝑐𝑠𝑠𝑠𝑠𝑓𝑓𝑠𝑠 (𝐴𝐴𝑠𝑠𝑙𝑙𝑐𝑐ℎ 𝐵𝐵) = 𝑞𝑞𝑓𝑓𝐴𝐴𝑐𝑐 = 1.2𝑐𝑐𝑁𝑁𝑓𝑓+𝛾𝛾1𝐷𝐷𝑓𝑓𝑁𝑁𝑞𝑞+.4𝛾𝛾2 𝐵𝐵𝑁𝑁𝛾𝛾
Where:
qult = ultimate bearing capacity
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c = cohesion of soil 𝑁𝑁𝑓𝑓, 𝑁𝑁𝑞𝑞, 𝑁𝑁𝛾𝛾 = Terzaghi’s bearing capacity factors 𝛾𝛾1= effective unit weight of soil above base of foundation 𝛾𝛾2= effective unit weight of soil below foundation 𝐷𝐷𝑓𝑓= depth of footing, or distance from ground surface to base of footing
B = width of continuous or square footing
R = radius of circular footing
𝑁𝑁𝑓𝑓, 𝑁𝑁𝑞𝑞, and 𝑁𝑁𝛾𝛾are functions of the soil’s angle of internal friction (𝜙𝜙). 𝑁𝑁𝑓𝑓cites the influence of
the soil’s cohesion on its bearing capacity while the term 𝑁𝑁𝑞𝑞reflects the influences of surcharge
and 𝑁𝑁𝛾𝛾shows the influence of soil weight and foundation width or radius. 𝑁𝑁𝑞𝑞= 𝐴𝐴𝜋𝜋𝑓𝑓𝑎𝑎𝜋𝜋𝜋𝜋𝑐𝑐𝑎𝑎𝑠𝑠2 (45∘+ 𝜋𝜋2 ) 𝑁𝑁𝑓𝑓= 𝑐𝑐𝐴𝐴𝑐𝑐𝜙𝜙(𝑁𝑁𝑞𝑞 −1) 𝑁𝑁𝛾𝛾= (𝑁𝑁𝑞𝑞 −1)𝑐𝑐𝑎𝑎𝑠𝑠(1.4𝜙𝜙)
Equations 1, 2, and 3 are applicable for both cohesive and cohesionless soils. Dense sand and
stiff clay produce general shear while loose sand and soft clay produce local shear. In the latter
soil conditions, c is replaced with 𝑐𝑐′= 23 𝑐𝑐 and 𝑁𝑁𝑓𝑓, 𝑁𝑁𝑞𝑞, and 𝑁𝑁𝛾𝛾are replaced with 𝑁𝑁′𝑓𝑓, 𝑁𝑁′𝑞𝑞, and 𝑁𝑁′𝛾𝛾and are modified by 𝜙𝜙′ = 𝑎𝑎𝐴𝐴𝑐𝑐𝑐𝑐𝑎𝑎𝑠𝑠(23 𝑐𝑐𝑎𝑎𝑠𝑠𝜙𝜙). With cohesive soils, shear strength is most
critical just after construction or as the load is first applied, at which time shear strength is
assumed to consist of only cohesion. In this case, 𝜙𝜙is zero. To evaluate cohesion, one can use the
unconfined compression test for ordinary sensitive or insensitive normally consolidated clay (c is
equal to half of the unconfined compressive strength 12 𝑞𝑞𝑢𝑢). For a sensitive clay, a field vane test
may be used to evaluate cohesion. For cohesionless soils, the c term in Equations 1, 2, and 3 is
zero where the value of 𝜙𝜙may be found through a STP test.
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Figure G1: Scan of textbook Figure 9-7 showing the relationship between bearing capacity
factors and degrees (Soils and Foundations, 284)
120
Figure G2: Scan of textbook Figure 9-9 showing the relationship between bearing capacity
factors (𝑁𝑁𝑞𝑞and 𝑁𝑁𝛾𝛾) and the angle of internal friction as well as the rough empirical relationship
between capacity factors or the angle and values of standard penetration resistance, N. (Soils and
Foundations, 286)
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Appendix G2: Settlement
Settlement is how much the soil changes as a result of vertical stresses placed on it. Settlement is
one of the most important geotechnical concepts to consider because it governs foundation
design for structures. Estimating settlement mainly depends on soil properties, especially
whether the soil is cohesive, like clay, or non-cohesive, like sand. In this project, there was no
indication of a cohesive clay layer, so more focus is spent on estimating the settlement on
granular soils. Moreover, since no clay is assumed to be present, it is recommended that the
project use shallow foundations. There are many methods that exist for estimating settlement of
shallow foundations on granular soils, but one method in particular suited this project. The
Schmertmann (1971) method outlined in Soils and Foundations by Liu et. al was used in this
case to estimate the settlement.
When clay soil is involved, the time rate of consolidation is important to consider because
settlement generally increases with time for this type of soil. When it comes to more granular
soil like the kind that exists at the project site, time rate of consolidation is not a major concern
because by the end of construction, most of the settlement from the loads will have occurred.
There are three main methods discussed in Soils and Foundations for estimating settlements of
shallow foundations on granular soil: Bazaraa, Burkand and Burbridge, and Schmertmann. Each
of these methods estimate settlement empirically, meaning that they rely on data collected at a
given site. Standard penetration testing (SPT) is the main method for empirical results used in
Bazaraa and Burkand and Burbridge. SPT could also be used in the Schmertmann method, but
cone penetration testing is used as the main data collection method, which is also the method
used for this project’s site testing.
The Schmertmann method uses the following equations:
𝑆𝑆𝑓𝑓=𝐶𝐶1𝐶𝐶2 𝛥𝛥𝛥𝛥∑2𝐵𝐵0 (𝐼𝐼𝑧𝑧/𝐸𝐸𝑠𝑠)𝛥𝛥𝑧𝑧 (for L/B = 0)
𝑆𝑆𝑓𝑓=𝐶𝐶1𝐶𝐶2 𝛥𝛥𝛥𝛥∑4𝐵𝐵0 (𝐼𝐼𝑧𝑧/𝐸𝐸𝑠𝑠)𝛥𝛥𝑧𝑧 (for L/B > 10)
where 𝑆𝑆𝑓𝑓=𝑠𝑠𝐴𝐴𝑐𝑐𝑐𝑐𝐴𝐴𝐴𝐴𝑠𝑠𝐴𝐴𝑠𝑠𝑐𝑐 𝐴𝐴𝑜𝑜 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝑐𝑐 𝑦𝑦𝐴𝐴𝑎𝑎𝐴𝐴𝑠𝑠 𝑎𝑎𝑜𝑜𝑐𝑐𝐴𝐴𝐴𝐴 𝑐𝑐𝐴𝐴𝑠𝑠𝑠𝑠𝑐𝑐𝐴𝐴𝑓𝑓𝑐𝑐𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝐶𝐶1 = 𝑐𝑐𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑐𝑐𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝑜𝑜𝑎𝑎𝑐𝑐𝑐𝑐𝐴𝐴𝐴𝐴 𝑜𝑜𝐴𝐴𝐴𝐴 𝐴𝐴𝑜𝑜𝑜𝑜𝐴𝐴𝑐𝑐𝑐𝑐 𝐴𝐴𝑜𝑜 𝑙𝑙𝐴𝐴𝛥𝛥𝑐𝑐ℎ 𝐴𝐴𝑜𝑜 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝐴𝐴𝑠𝑠𝐴𝐴𝐴𝐴𝑙𝑙𝑠𝑠𝐴𝐴𝑠𝑠𝑐𝑐 𝐶𝐶1 =1 −0.5(𝛥𝛥0/𝛥𝛥𝛥𝛥)
where
𝛥𝛥0 =𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴 𝐴𝐴𝑜𝑜𝐴𝐴𝐴𝐴𝐴𝐴𝑓𝑓𝐴𝐴𝑙𝑙𝐴𝐴𝑠𝑠 𝛥𝛥𝐴𝐴𝐴𝐴𝑠𝑠𝑠𝑠𝑓𝑓𝐴𝐴𝐴𝐴 𝑎𝑎𝑐𝑐 𝐴𝐴𝑎𝑎𝑠𝑠𝐴𝐴 𝐴𝐴𝑜𝑜 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 (𝑘𝑘𝑁𝑁/𝑠𝑠2) 𝛥𝛥𝛥𝛥=𝑠𝑠𝐴𝐴𝑐𝑐 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝛥𝛥𝐴𝐴𝐴𝐴𝑠𝑠𝑠𝑠𝑓𝑓𝐴𝐴𝐴𝐴 𝑠𝑠𝑠𝑠𝛥𝛥𝐴𝐴𝑠𝑠𝐴𝐴𝑙𝑙 𝐴𝐴𝑠𝑠𝑐𝑐𝐴𝐴 𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴 𝑎𝑎𝑐𝑐 𝐴𝐴𝑎𝑎𝑠𝑠𝐴𝐴 𝐴𝐴𝑜𝑜 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 (𝑘𝑘𝑁𝑁/𝑠𝑠2 ) 𝐶𝐶2=𝑐𝑐𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑐𝑐𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 𝑜𝑜𝑎𝑎𝑐𝑐𝑐𝑐𝐴𝐴𝐴𝐴 𝑜𝑜𝐴𝐴𝐴𝐴 𝐴𝐴𝑜𝑜𝑜𝑜𝐴𝐴𝑐𝑐𝑐𝑐 𝐴𝐴𝑜𝑜 𝑐𝑐𝐴𝐴𝐴𝐴𝐴𝐴𝛥𝛥 𝑐𝑐𝑦𝑦𝛥𝛥𝐴𝐴 𝛥𝛥ℎ𝐴𝐴𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴𝑠𝑠 𝑎𝑎𝑠𝑠𝑙𝑙 𝐴𝐴𝑐𝑐ℎ𝐴𝐴𝐴𝐴 𝑜𝑜𝑎𝑎𝑐𝑐𝑐𝑐𝐴𝐴𝐴𝐴𝑠𝑠 𝐴𝐴𝑜𝑜𝐴𝐴𝐴𝐴 𝑐𝑐𝑠𝑠𝑠𝑠𝐴𝐴 𝐶𝐶2 =1 +0.2(𝐴𝐴𝐴𝐴𝑓𝑓 10𝑐𝑐)
where
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𝑐𝑐=𝑐𝑐𝑠𝑠𝑠𝑠𝐴𝐴 𝑠𝑠𝑠𝑠 𝑦𝑦𝐴𝐴𝑎𝑎𝐴𝐴𝑠𝑠 𝐼𝐼𝑧𝑧=𝑠𝑠𝑐𝑐𝐴𝐴𝑎𝑎𝑠𝑠𝑠𝑠 𝑠𝑠𝑠𝑠𝑜𝑜𝐴𝐴𝑓𝑓𝐴𝐴𝑠𝑠𝑐𝑐𝐴𝐴 𝑜𝑜𝑎𝑎𝑐𝑐𝑐𝑐𝐴𝐴𝐴𝐴 𝑜𝑜𝐴𝐴𝐴𝐴 𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴 𝑧𝑧𝐴𝐴𝑠𝑠𝐴𝐴 𝑧𝑧 𝑙𝑙𝐴𝐴𝛥𝛥𝑐𝑐ℎ 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑜𝑜𝐴𝐴𝑓𝑓𝑠𝑠𝑙𝑙𝑎𝑎𝑐𝑐𝑠𝑠𝐴𝐴𝑠𝑠 (𝑙𝑙𝑠𝑠𝑠𝑠𝐴𝐴𝑠𝑠𝑠𝑠𝑠𝑠𝐴𝐴𝑠𝑠𝐴𝐴𝐴𝐴𝑠𝑠𝑠𝑠) 𝐸𝐸𝑠𝑠=𝑠𝑠𝐴𝐴𝑙𝑙𝑓𝑓𝐴𝐴𝑓𝑓𝑠𝑠 𝐴𝐴𝑜𝑜 𝐴𝐴𝐴𝐴𝑎𝑎𝑠𝑠𝑐𝑐𝑠𝑠𝑐𝑐𝑠𝑠𝑐𝑐𝑦𝑦 𝐴𝐴𝑜𝑜 𝑠𝑠𝑎𝑎𝑠𝑠𝑙𝑙 (𝑘𝑘𝑁𝑁/𝑠𝑠2) 𝑧𝑧=𝑠𝑠𝑎𝑎𝑠𝑠𝑙𝑙′𝑠𝑠 𝐴𝐴𝑎𝑎𝑦𝑦𝐴𝐴𝐴𝐴 𝑐𝑐ℎ𝑠𝑠𝑐𝑐𝑘𝑘𝑠𝑠𝐴𝐴𝑠𝑠𝑠𝑠 (𝑠𝑠)
The modulus of elasticity will depend on the cone penetration resistance, 𝑞𝑞𝑓𝑓. It’s relationship to
the elastic modulus depends on the soil type. The cone penetration resistance can also be related
to SPT as summarized by the table below.
Table G3: The relationship between elastic modulus, cone penetration resistance, and standard
penetrations blows.
Soil Type
Approximate Values of 𝑬𝑬𝒔𝒔
In Terms of 𝑵𝑵 In Terms of 𝒒𝒒𝒄𝒄
Sand-silt mixture 4N 1.5𝑞𝑞𝑓𝑓
Fine-to-medium sands, fine-
medium-coarse sands
7-10N 2-3𝑞𝑞𝑓𝑓
Sand-gravel mixtures 12N 4𝑞𝑞𝑓𝑓
Figures G1 and G2 may be useful in determining what soil type is present, and thus, which
relationship to use when approximating the elastic modulus.
Figure G4: Criteria for describing the structure of coarse-grained soils in their natural or in-
place condition.
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\
Figure G5: Typical values of void ratio and porosity of granular soils.
Appendix G3: Scour
Scour is a destructive phenomenon in which a flood erodes and weathers the soil around the
foundations of a bridge. Bridges are often designed for hydraulic resistance to a flood of a certain
size, often the 100-year flood. Bridges must resist failing due to scour during floods that are
larger than the design flood, because bridges are damaged in floods and destroyed by scour.
Flood damage can be repaired quickly, bridge destruction cannot. Therefore, it makes economic
sense to build a bridge that can withstand a larger flood than the design flood to ward off the
chance that the bridge must be totally replaced before the end of its service life.
What follows is a condensed version of the explanation of how to conduct a scour analysis from
Hydraulic Engineering Circular no. 18, “Evaluating Scour at Bridges.”
Evaluating Scour at Bridges. Hydraulic Engineering Circular No. 18. 2012.
Adapted from HEC 2.2-2.4
2.2 GENERAL DESIGN PROCEDURE
The general design procedure for scour outlined in the following steps is recommended for
determining bridge type, size, and location (TS&L) of substructure units:
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Step 1. Select the flood event(s) that are expected to produce appropriately severe scour
conditions. Balancing risk of failure against safety, reliability, and economic requirements
suggests that scour should be evaluated for an event larger than the hydraulic design flood. For
example, if a bridge is designed for a hydraulic capacity of Q25, then the Scour Design Flood
Frequency would be for a Q50 flood and the Scour Design Check Flood Frequency would be the
Q100 flood. In all cases, if there is an overtopping event that causes greater hydraulic stresses to
the bridge than the hydraulic design event then that flood should be used for computing scour
and designing the foundations. Overtopping refers to flow over the approach embankment(s), the
bridge itself, or both. See Appendix B for a discussion of extreme event combinations and design
flood exceedance probabilities.
[Barb Comment: We are designing for 100 year flood = design flood, so according to [1] (p 2.1)
· Hydraulic design flood frequency, Qd = 100 yrs
· Scour design flood frequency, Qs = 200 yrs
· Scour design check flood frequency, Qc = 500 yrs
· Unsure if the magnitude of overtopping flood would > Qd or Qs, but worth checking.
Step 2. Develop hydraulic parameters necessary to estimate scour for the flood flows in Step 1.
This is typically done by the application of a one- or two-dimensional hydraulic model. Care
must be taken to evaluate the full range of hydraulic conditions that could impact the flow
conditions at and near the bridge being designed. These conditions could include the effects of
downstream tail water, confluences with other streams, etc.. For one-dimensional hydraulic
analysis the U.S. Army Corps of Engineers (USACE) Hydrologic Engineering Center's River
Analysis System (HEC-RAS) is recommended for this task (USACE 2010a). For bridges with
complex flow characteristics such as flow on embankments skewed to the flood flows, multiple
floodplain openings, wide flood plains, highly contracted flows, etc., it is recommended that the
FHWA's FST2DH (FHWA 2003b) two-dimensional hydraulic analysis model be used.
Step 3. Using the six-step Specific Design Approach for Scour in Section 2.4, estimate total
scour for the hydraulic conditions identified from Steps 1 and 2 above. The resulting scour
computed from the selected flood event should be considered in the design of a foundation. For
this condition, minimum geotechnical safety factors commonly accepted by FHWA, AASHTO,
and DOTs should be applied. For example, for a pile designed to have its bearing capacity
through friction, a commonly applied factor of safety ranges from two to three.
Step 4. Plot the total scour depths obtained in Step 3 on a cross section of the stream channel and
floodplain at the bridge site.
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Step 5. Evaluate the results obtained in Steps 3 and 4 for reasonableness. Based on the judgment
of a multi-disciplinary team of hydraulic, geotechnical, and structural engineers, the
reasonableness of the results must be evaluated. There are many factors that could affect the
magnitude of the overall scour estimate. They could include storm duration, erodibility of
channel materials, flow conditions, ice and debris, and many others. In order to assure the most
reliable estimates of scour, one must also have an understanding of the theory and development
of the procedures used to determine scour. Based on the factors mentioned above, the scour
depth(s) adopted for use in design may differ from the computed value(s).
Step 6. Evaluate the proposed bridge size, configuration, and foundation elements on the basis of
the scour analysis performed in Steps 3 through 5. Modify the design as necessary based on the
following discussion:
1. Develop an understanding of the overall flood flow pattern at the bridge site for the design
conditions. Also, develop an understanding of the dynamic channel and floodplain characteristics
for the reach of the stream that contains the bridge. Use the understanding of these factors to
identify those bridge elements most vulnerable to flood flows, channel change, and resulting
scour.
2. To the extent possible, modify components of the bridge length, location, configuration,
and sub-structure elements to minimize scour. The following factors can lead to reduced scour
depths.
a. Increase the bridge length. Increasing the bridge length generally reduces depths of flow
and velocities through the bridge opening which reduces the magnitude of scour.
b. Locate new or replacement bridges such as they experience as little scour as possible. This
means the bridge would cross the floodplain as perpendicular as possible to the flood flows and
would be located in the floodplain where the conveyance is highest.
c. Provide substructure elements that are not as susceptible to scour as others. For example,
piers that are aligned with the flow do not experience as much scour as piers that are not aligned
with the flow. Also, certain pier configurations are not as susceptible to scour as others. Round
nosed piers are not as susceptible to scour as square nosed piers and circular piers are not as
susceptible to scour caused from non-aligned flow as are solid-wall piers.
d. Design and install guide banks to reduce scour at the abutments. Guide banks help align
flow with the abutments and minimize the adverse flow conditions at the abutments that
contribute to scour. Guide banks also provide an additional benefit in that they make the bridge
opening more hydraulically efficient.
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Step 7. Perform the bridge foundation analysis on the basis that all streambed material in the
scour prism above the total scour line (Step 4) has been removed and is not available for bearing
or lateral support. All foundations should be designed in accordance with the AASHTO Standard
Specifications for Highway Bridges (AASHTO 1992a). In the case of a pile foundation, the
piling should be designed for additional lateral restraint and column action because of the
increase in unsupported pile length during and after scour. In areas where the local scour is
confined to the proximity of the footing, the lateral ground stresses on the pile length which
remains embedded may be significantly reduced from the pre-local scour conditions."
Hydraulic Engineering Circular pp 2.2-2.4
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Appendix H: Geotechnical Analysis of Proposed Bridge Site
Before designing the necessary foundations or general structures needed for the bridge, it was
important to learn more about the soil present and its effects on scour, bearing capacity, and
settlement. The goal of these analyses, including scour, is to determine any critical conditions
that drive the engineering decisions on the foundations of the bridge. The following sections
provide a brief overview of what soil conditions were found after two different occasions of soil
testing.
Appendix H1: Various Geotechnical Tests
The table below is a compilation of various geotechnical tests possible. This table was helpful in
determining which tests were needed and possible given the equipment available. For the first
soil analysis, a sieve test was run on a sample of collected soil. In the second test, a Dynamic
Cone Penetration (DCP) test was run in addition to a sieve test.
Table H1: A list of possible geotechnical tests that may prove useful to the project from Sabatini
et al, Geotechnical Circular No 5 (2002).
Appendix H1.1: First Field Test, 10/4/2020
Geotechnical analyses are necessary to understand the current soil conditions of the proposed
bridge site. A soil sample was taken at the location shown in Figure H2 approximately two feet
below the surface of the ground as shown in Figure H3. After conducting a sieve test, the test
data was analyzed to produce a grain size distribution (GSD), the coefficient of uniformity and
curvature was found, and the unified soil classification (USC) guide was used to determine the
soil characteristics. Tables H4 and H6 organize the grain size data by the percentage of soil
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retained and passing to which were used the plot points on the GSD curves in Figures H5 and
H8. Using the results shown in Tables H4 and H7 and the USC guide in Figure H10, the
analysis concluded the soil is most likely well graded, and it is on the cusp of being classified as
SP, gravelly sands with little or no fines, or SM-SW, sand with silt.
Figure H2: Screenshot taken at time of soil collection providing satellite imagery with
approximate coordinates of sample location.
Figure H3: Photograph of hole dug to collect soil sample with a drawn on scale to depict hole
depth. The image shows approximately a foot of darker, organic material near the surface and a
lighter, sandier soil where the sample was collected from.
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Table H4: Sieve analysis calculations of soil percentage retained and passing for sample A.
Sieve No. Mass Retained (g) % Retained % Passing
4 .5 .032 99.968
10 .5 .032 99.936
20 17.5 1.12 98.816
40 287.0 18.5 80.316
60 509.5 32.9 47.416
100 348 22.5 24.916
200 217.5 14.0 10.916
Tin 169.5 10.93 0
Total 1550 ___ ___
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Figure H5: Grain size distribution curve using values calculated from Table H4. Additionally,
the curve is annotated with the needed D10, D30, and D60 values.
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Table H6: Summary of results from GSD curve and USC guide for soil sample A.
Soil Sample A
D10 = .075 mm
D30 = .16 mm
D60 = .3 mm
Cu = 4
Cc = 1.14
Well graded:
D60 >> D10,
Cu > 6 (sand) and 1 < Cc < 4
Uniformly graded:
1 < Cu < 4 or 6
From Unified Soil Classification:
Well graded, SP or SM-SW (sand with silt)
Table H7: Sieve analysis calculations of soil percentage retained and passing for sample B.
Sieve No. Mass Retained (g) % Retained % Passing
4 0 0 100
10 .5 .031 99.969
20 19 1.19 98.779
40 280 17.6 81.179
60 520 32.6 48.579
100 344.5 21.6 26.979
200 248 15.6 11.379
Tin 181 11.36 0
Total 1593 ___ ___
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Figure H8: Grain size distribution curve using values calculated from Table I7. Additionally,
the curve is annotated with the needed D10, D30, and D60 values.
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Table H9: Summary of results from GSD curve and USC guide for soil sample B.
Soil Sample B
D10 = .075 mm
D30 = .15 mm
D60 = .3 mm
Cu = 4
Cc = 1
Well graded:
D60 >> D10,
Cu > 6 (sand) and 1 < Cc < 4
Uniformly graded:
1 < Cu < 4 or 6
From Unified Soil Classification:
Well graded, SP or SM-SW (sand with silt)
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Figure H10: Unified Soil Classification guide used to make conclusions for soil analyses as seen
in Tables H4 and H7.
Appendix H1.2: Second Field Test, 11/14/2020
November 14, 2020
Site Visit Conditions ❖ Around 12:30, a bit overcast ❖ Soil appeared to be damp from recent rainfall ❖ Hole from previous soil sample identified ❖ By 3:30, sunny
Timeline ❖ 11 AM - Ruth, Auden, Professor Rubin meet next to Sage Hall and discuss plan for
getting supplies ready to take to site
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❖ 11:30 AM - Meet at outdoor tennis court parking lot by the athletic fields, unpack
necessary equipment, organize what tools and gear we would need to take and leave
behind ❖ 11:45 AM - Begin hike to proposed bridge site ❖ 12:05 PM - Met Professor Howe along the trail near the Village Hill path connection ❖ 12:30 PM - Arrived at proposed site location ❖ 12:35 PM - Identified hole dug from initial soil sample, decided to use this location for
auger and DCP tests, conducted a brief safety training for using the testing devices ❖ 12:45 PM - Started Zoom session for DC team, began to dig first auger hole ❖ 1:00 PM - Begin DCP Test ❖ 1:15 PM - Since hard rock hit around 50 in, second hole started about 1 foot next to first
hole ❖ 1:45 PM - Tough roots hit, around 48 in, third hole started about two feet away from first
hole ❖ 1:45 - 2:55 PM - Work on the third hole, conduct an auger test until about 5 ft. and DCP
test to about 8.75 ft. ❖ 3 PM - Began clean up and started to pack ❖ 3:15 PM - Started hike back to tennis court parking lot ❖ 4 PM - Arrived to parking lot ❖ 4:15 PM - Met Professor Rubin at Ford Hall parking lot to unpack and fully label soil
samples ❖ 4:30 PM - Walk back to Ziskind House
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Figure H11: The data sheet created for the geotechnical test conducted on 11/14/20.
Design Clinic 2020-2021
NOPS/MRGI
Collected Site Data
Date: 11/14/2020
Sample: “AH1”
Equipment Used: DGSI Standard Hand Auger, Dynamic Cone
Penetrometer with 9.4 lb hammer
Sample Location: (42.3224232, -72.6567691)
Sample Taken By: Ruth Penberthy, Aaron Rubin, Auden Balouch
Depth to Bedrock:
Unsure
Depth to Water Table/Groundwater:
Possibly 54-60 in below surface
Depth
(in.)
Subsurface Condition Notes # blows / 3in Sample
No.
Additional Notes
0-24 First collected sample, darker
brown, higher moisture, more
organic material,
~24 in sandier material
-
24-27 Still sandier material, more
yellow in color
1
27-30 2
30-33 2
33-36 2
36-39 2 A
39-42 3
42-45 3
45-48 7
48-51 7 B Ended second hole here, hit dense roots
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51-54 *21* Ended first experimental hole here, hit
rock like material hence the higher blow
count
54-57 Started to become much drier,
possibly suggesting water
table is above this depth,
brighter yellow color
3 Started to become so dry that samples
couldn’t be extracted, poured water on
hole in attempt to
57-60 9 C
60-63 9
63-66 8 D
66-69 Started to hit gravel, making it
difficult to extract soil
11 Sample E might indicate possible signs of
glacial deposit
69-72 8 E
Depth
(in.)
Subsurface Condition
Notes
# blows / 3in Sample
No.
Additional Notes
72-75 9
75-78 7
78-81 23
81-84 35
84-87 14
87-90 30
90-93 24
93-96 38
138
96-99 43
99-102 100
Figure H12: The GSD graph for sample C.
Table H13: The USC card for sample C.
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Soil Sample C
D10 = .15 mm
D30 = .3 mm
D60 = 2.9 mm
Cu = 19.3
Cc = .207
Poorly graded:
D60 >> D10
From Unified Soil Classification:
SP, poorly graded sands or gravelly
sands, little or no fines
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Figure H14: The GSD for sample E.
Table H15: The USC card for sample E.
141
Soil Sample E
D10 = .15 mm
D30 = .37 mm
D60 = 3 mm
Cu = 20
Cc = .304
Poorly graded:
D60 >> D10,
From Unified Soil Classification:
SP, poorly graded sands or gravelly
sands, little or no fines
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Appendix I. Footing Calculations
This section outlines the process used to create a bearing capacity, contact pressure, and retaining
wall calculator in Google Sheets. Much of the information in these calculators is based on results
from the dynamic cone penetration (DCP) test that was done on the side of the Mill River that is
closest to the agricultural fields. Below is a screenshot of the DCP datasheet. The most important
columns in this data are the DCP (Blows/foot), Angle of Internal friction (degrees), and Unit
Weight of Soil (lbs/ft^3). Throughout these sections, this datasheet can be referenced so it is
clear where these values come from as well as how they are related.
Figure I1: The DCP datasheet with information used to create the bearing capacity, contact
pressure, and factor of safety calculators.
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Appendix I1: Bearing Capacity
The footing designed for this project was created by following the procedures outlined in
Chapter 9: Shallow Foundations and Chapter 13: Retaining Structures in the 7th Edition of Soils
and Foundations by Liu and Evett. One of the first steps of this procedure was to calculate
bearing capacity. A Google Sheet was created to help streamline the design process as
dimensions like Df, distance from ground surface, and B, width of continuous footing, could be
changed easily and a new bearing capacity would result. An image of what this calculator looks
like can be seen below.
Figure I2: A screenshot of the bearing capacity calculator.
Explaining how the Google Sheet was created begins first with the type of footing needed in this
design. Based on the text, it was decided that a continuous footing would be the most appropriate
option. An example of what this looks like is shown below.
Figure I3: Simple diagram of a continuous footing from figure 9-2 in Soils and Foundations.
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The ultimate bearing capacity equation changes based on the type of footing, so the equation that
corresponds to the continuous footing was used. In that equation, there are the terms Nc, Nq, and
Ny, known as the Terzaghi bearing capacity factors. These can be seen below.
Ultimate bearing capacity equation for a continuous footing.
These factors rely on characteristics of the soil, specifically its cohesion and internal angle of
friction. Both of these factors were determined previously using the results from the dynamic
cone penetration (DCP) testing. The table that relates blows per foot to internal friction angle is
shown below.
Table I3: Relation between bearing capacity factors and internal friction angle.
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Using the blows of the DCP test, the internal friction angle was deduced, and thus, the bearing
capacity factors. Since, however, the soil test results showed no evidence of cohesive soil, the
soil was assumed to be cohesionless which meant that the Nc term could be ignored.
The next parameters needed were the unit weights of the soil above the base of the footing, y1,
and the unit weight of the soil below the footing, y2. Based on the blows per foot, the unit
weights were able to be estimated. The table used for this relationship is shown below.
Table I4: Empirical values for unit weight of granular soils based on the dynamic cone
penetration blows per foot (from Bowels, Foundation Analysis).
Appendix I2: Contact Pressure
After the bearing capacity was calculated, the next step in the process was to calculate contact
pressure. A screenshot of the contact pressure calculator is shown below.
Figure I5: Contact pressure calculation sheet.
146
Contact pressure relies mainly on the geometry of the footing itself. Some preliminary values for
the general dimensions of the footing were used initially, but after various iterations of the design
process, the final geometries are reflected in the screenshot above. More specifically, the contact
pressure relied on the total axial vertical load. In order to calculate that value, the column load,
the weight of the footing’s base pad, the weight of the footing’s pedestal, and the weight of the
backfill soil were needed.
Starting with the column load, that was a very conservative estimate of the load each footing
would have to be designed for. This value was informed by the dead load, snow load, and wind
load the bridge would experience divided by two since there would be two footings on either side
supporting it. Next, the weight of the footing’s base pad was calculated using the unit weight of
concrete, the area of the footing pad, and the thickness of said pad. The weight of the footing’s
pedestal was calculated similarly; only the area of the stem, its thickness, and its length were
used along with the unit weight of concrete. The weight of the backfill soil was calculated using
the area of the footing base minus the area of the footing web multiplied by the length of the
stem and the unit weight of soil. Finally, all of these values could be added together to get the
total axial load on the footing. This could then be divided by the area of the footing’s base pad
which resulted in the final contact pressure.
Appendix I3: Retaining Wall
In addition to the bearing capacity and contact pressure calculations, a retaining wall analysis
was needed to ensure the footing could withstand overturning and sliding. One of the first values
for calculating the factor of safety for overturning and sliding is active earth pressure. The
calculator necessary for this calculation can be seen below.
147
Figure I6: Part of the retaining wall calculation sheet showing active earth pressure.
Active earth pressure depends on the earth pressure coefficient and the depth of the footing base
as seen in the equation below.
The earth pressure coefficient is determined by the soil type. In this case, the soil at the site was
assumed to be type 1 which is “coarse-grained soil without admixture of fine soil particles, very
free draining (clean sand, gravel, broken stone).” According to Figure 13-3 in Chapter 13, the
earth pressure coefficient with this soil and slope is 30.
148
Figure I7: Active earth pressure coefficient for soil type 1.
Earth pressure is then used to determine the overturning moment, and thus its factor of safety, as
well as the sliding factor of safety. All of these factors also depend on the geometry of the
footing, of course. In fact, part of the calculator is specifically used for finding the moments
about the toe of the footing as well as the weight of each part of the footing. With the geometries
of the footing, earth pressure, and moments set, the factors of safety can be easily determined
using the equations below.
Figure I8: The factor of safety equations for overturning and sliding.
The results of the factor of safety calculations can then be compared with the allowable factor of
safety for these two parameters to see if the geometries selected for the footing are appropriate
and safe. The allowable factors for each factor of safety are provided below.
149
Figure I9: Factor of safety ranges for overturning and sliding.
The results of the factor of safety analysis can be seen in the calculator. The “OK” signifies that
the footing geometries selected are theoretically appropriate for the given bridge design.
Figure I10: Factor of safety evaluation for footing geometries.
Appendix J. Truss Research
The following appendix section includes the research done on the carious truss shapes along with
a corresponding brief description.
150
Appendix J1: The K Truss
The K Truss is a variation on the Parker Truss which is a variation of the Pratt Truss. There are
two configurations of the K truss; the first is shown in Figure 13a which forms a diamond of
sorts at the center of the bridge and the other in Figure 13b forms more of an “X” at the center.
Figure J1: The first form of the K Truss where the center of the structure forms a diamond.
The advantage of using the K Truss is that it reduces the likelihood of buckling under pressure
due to the shorter diagonal members used. However, this design is more complex because of all
the members involved 17. This increases the cost and time needed to construct it. Although unique
in design, the complexity involved with the K Truss is unnecessary for this project, especially
when there are other more simple designs available.
Figure J2: The second form of the K Truss that forms an “X” shape at the center of the
structure.
Appendix J2: The Warren Truss
The Warren Truss is one of the most widely known and used truss bridges. It’s name comes from
its patented design by James Warren and is made up of equilateral triangles connected along the
top and bottom chords which span the length of the bridge. It is possible to add both vertical
members in between the equilateral triangles and overhead bracing if desired. Warren Trusses
work best when the load is distributed as each member takes on a portion of the load. That being
17 https://www.machines4u.com.au/mag/4-types-of-truss-bridges-which-is-worth-the-weight/
151
said, the Warren Truss’s performance under concentrated loads is not as optimized as it is for
distributed loads 18.
Figure J3.1: The most basic Warren Truss configuration made up of equilateral triangles.
Figure J3.2: An additional vertical member added to the most basic Warren Truss configuration.
Unlike the K Truss, the Warren Truss is very simple in design, so the cost and construction time
are minimized. Although the Warren Truss is said to work best for distributed loads, it could be a
viable option because of its simple and cost effective design.
Some real life examples are shown in Figures J4 and J5 19. These are possible designs that could
work for this project with some variation in materials as a possibility.
18 https://skyciv.com/docs/tutorials/truss-tutorials/types-of-truss-structures/#k
19 http://www.wheeler-con.com/recreation-bridges/steel-recreation-bridges/warren-truss-prefabricated-
steel-bridges/
152
Figure J4: Warren Truss with wood decking and handrails and steel superstructure.
153
Figure J5: Warren Truss with steel vertical members, wood decking and handrails, and an
overhead bracing.
Two other variations of the Warren Truss include the Double Intersection Warren and the
Lattice. The Double Intersection Warren is equivalent to two warren bridges superimposed and
offset over each other as shown in Figure J6.
Figure J6: Two Warren Trusses superimposed and offset over each other.
The Lattice is a bit more complex because it has more than two warren trusses virtually
superimposed and stacked atop each other as seen in Figure J7.
Figure J7: More than two Warren Trusses superimposed and stacked.
154
Since these are all fundamentally Warren Trusses, they have relatively the same advantages of
load carrying capacity, but increase in complexity, and thus cost, with the addition of more
members. The Warren Truss itself is a viable option for this project, and although unique, the
Lattice’s complexity is not necessary for this project.
Appendix J3: The Pratt Truss:
The Pratt Truss 20 was made of right triangles oriented so that the diagonal members point toward
the center of the bridge, aside from the two right triangles at either end of the bridge (Figure 20).
The Pratt Truss can support heavy loads, can span short and long distances, and each member is
used efficiently. Although each member is used efficiently, the bridge can end up being
relatively heavy because of all of the components. Moreover, materials can be wasted if the truss
is not designed properly.
Appendix J4: The Baltimore Truss:
The Baltimore Truss is a variation on the Pratt Truss where additional diagonals are added
specifically to the lower parts of the truss. This design is typically used for railroad designs, but
it is a simple design with high strength.
Figure J8: The Baltimore Truss
Appendix J5: The Howe Truss:
The Howe Truss can be thought of as the opposite of the Pratt Truss; it is made up of right
triangles with diagonal members that point away from the center of the bridge. It has similar
advantages and disadvantages as the Pratt Truss.
20 https://navajocodetalkers.org/the-pros-and-cons-of-truss-bridges/
155
Figure J9: The Pratt Truss above compared to the Howe Truss below 21.
Appendix J6: The Bowstring Truss:
The Bowstring Truss has an arched top chord that can either meet the bottom chord at the deck
or the end post that connects the bottom and top chords. The Bowstring truss has diagonal
members oriented in a Pratt-like way in that they point toward the center of the bridge. This type
of truss is unlike its more square counterparts, making its design stick out amongst the rest.
21 https://www.quora.com/What-is-pratt-truss
156
Figure J10: Bowstring Truss in Durango, CO where the top chord meets the bottom chord at the
deck.22
22 http://www.wheeler-con.com/recreation-bridges/steel-recreation-bridges/bowstring-truss/
157
Figure J11: Bowstring Truss in Savannah, IL where the top chord meets the bottom chord at the
deck and the diagonal trusses meet each other in the middle of each section10.
158
Appendix K: Decking Material Research
The following is research done on the various types of decking material.
Appendix K1 Wood:
Wood decking for bridges is typically made up of sawn lumber planks, nail-laminated lumber
(nail-lam), or glue-laminated lumber (glulam). Sawn lumber planks for decking is one of the
oldest and most simple methods used in bridge decking. It can be oriented in the transverse or
longitudinal direction of the bridge, but it is not water resistant and is subject to weathering.
Since the introduction of glulam, nail-lam has become less common. Nail-laminated decks are
most commonly used in a transverse orientation on sawn lumber or steel beams spaced 2 to 6
feet apart. As spaces between beams increases, the service life decreases for this type of decking
because of deflection and variation in water content.
According to the United States Department of Agriculture 23 (USDA), glulam is the “...most
common type of timber deck and is used in two basic configurations, non-interconnected and
doweled. Non-interconnected panels are placed edge to edge, with no connection between
adjacent panels. Doweled panels are interconnected with steel dowels to improve load
distribution and reduce differential displacements at the panel joints. Doweled panels are more
costly to fabricate and construct but can result in thinner decks and better performance for
asphalt wearing surfaces. Glulam decks are stronger and stiffer than conventional plank or nail-
laminated decks because of the homogeneous bond between laminations and the dispersion of
strength-reducing characteristics of glulam. Glulam panels can be constructed to form a
watertight surface and afford protection for supporting beams and other components. Because of
their increased stiffness, glulam decks also provide a firm base for asphalt pavement, which is
frequently used as the wearing surface. Panels are completely fabricated and drilled for deck
attachment prior to preservative treatment, producing estimated service lives of 50 years or
more.”
Appendix K2: Steel
For steel decking, it is typically broken up into open grid decks, half filled grid decks, filled grid
decks, and Exodermic decks. Open grid decks are steel grids that are not filled with concrete.
While walking over this deck, one would see through the floor below. Half filled grid decks are
partially filled with concrete making them lighter in weight while keeping its stability. Filled grid
23 https://www.fpl.fs.fed.us/documnts/misc/em7700_8--entire-publication.pdf
159
decks are completely filled with concrete, but can only span 10 ft. Exodermic decks is an unfilled
steel grid with a slab of reinforced concrete over it. These offer greater span capacities and have
a slight weight advantage over the half filled grid decks 24.
Figure K1: Diagrams of half filled grid decking (top left), fully filled grid decking (top right),
Exodermic decking (bottom left), and open grid decking (bottom right).
Appendix K3: Concrete
Concrete decking is the most common for steel bridges. They can be reinforced with steel and
can either come precast or be poured on site. Although most common and simple, concrete has
high environmental impacts compared to other materials like wood, steel, and FRP. The
aesthetics of concrete are not particularly attractive or adjustable besides adding paint that would
have to be reapplied after a certain amount of time or dye during the manufacturing process.
24 http://www.bgfma.org/grids.htm
160
Appendix K4: Fiber Reinforced Plastic (FRP)
According to the American Concrete Institute25, FRP “...materials are composite materials that
typically consist of strong fibers embedded in a resin matrix. The fibers provide strength and
stiffness to the composite and generally carry most of the applied loads. The matrix acts to bond
and protect the fibers and to provide for transfer of stress from fiber to fiber through shear
stresses. The most common fibers are glass, carbon, and synthetic fibers.” Over the years, using
FRP materials for bridge structures and bridge decking has become more popular. The material
is strong, lightweight, has a straightforward installation process, and does not require much
maintenance when installed. In addition, FRP does not rot, warp, corrode, or conduct electricity.
All of the previously listed are advantages of FRP, but it is not a perfect material, however. Some
of the disadvantages of FRP are that it uses different drill bits and saw blades typically used for
steel and timber, lack of experience with them in industry, lack of standards and codes, and high
cost relative to timber and unpainted low-carbon steel 26. Two tables 27 comparing characteristics
of FRP, wood, steel, and aluminium are provided below.
25
https://www.concrete.org/topicsinconcrete/topicdetail/Fiber%20Reinforced%20Polymer?search=Fiber%20
Reinforced%20Polymer 26 https://www.fs.fed.us/t-
d/pubs/htmlpubs/htm06232824/page03.htm#:~:text=One%20disadvantage%20of%20FRP%20materials,u
sed%20with%20wood%20or%20steel. 27 https://bedfordreinforced.com/resources/#product-literature
161
Table K2: A table comparing the attributes of FRP, aluminum, steel, and wood decking
materials.
162
163
Appendix K5: Decking Selection - Matrix Scoring
Table K3: Scoring descriptions for 1s and 5s in the decking matrix.
Category Rating 1 Rating 5
Environmental Impact very hazardous to the
environment
not hazardous at all
Maintenance heavily maintained little to no maintenance
Impact Resistance easily deform on impact hard to permanently deform
Weight very heavy lightweight
Cost expensive upfront and in the
future
inexpensive upfront and in the
future
Aesthetics material does not align with
overall aesthetics of bridge or
natural environment
material matches overall
aesthetics of bridge and fits
natural environment
164
Appendix L. Superstructure Concept Selection
This appendix provides more details on the bridge concept selection process and the matrix that
corresponds to it. The names of the conceptual designs in this appendix do not match the report,
but the three concepts that are mentioned in the report go by the names of “kinda #artsy”
(Bowstring), “Another Day, Another Dollar” (Pratt Option 1), and “She’ll Do” (Pratt Option 2).
Appendix L1: Bridge Concepts
The bridge concepts are described in the table below from the most extravagant on the left to the
least extravagant on the right.
Table L1: All five concepts considered for the bridge component of the project
Maximum
Arte
Kinda Artsy Another Day
Another
Dollar
Lumberjacks
Dream
She’ll do
Superstructure Bowstring Bowstring Pratt Pratt Pratt
Structural
Material
Wood Steel Steel Wood Steel
Lookout Type Bubble in
the Middle
Bubble in the
Middle
Non-
structural
middle
On abutment On abutment
Art Location
on Bridge
Sides over
water
Railing under
abutments
Sides over
water
Railings near
abutment
Railings near
abutments
Appendix L2: Initial Evaluation
Appendix L2.1: Reference Concept
“Another Day Another Dollar”
● SUPERSTRUCTURE: pratt
● STRUCTURAL MATERIAL: steel
● LOOKOUT TYPE: non-structural middle
● ART LOCATION: sides over water
This concept was selected as our reference because it’s what we would like to do if approval
from locals and money permit its construction.
165
Table L2: Filled Selection Matrix (Pugh)
Selection Criteria Maximum
Arte
kinda #artsy Another Day
Another
Dollar (ref)
lumberjack’s
dream.
She’ll Do
Abutment Impact + + 0 + +
Carbon Footprint + 0 0 + 0
Construction Cost - - 0 - 0
Maintenance Cost - 0 0 - 0
Visual Weight - + 0 - +
Interactive
Potential
+ + 0 + +
Sum Total 0 2 0 0 3
Rank 3 2 3 3 1
Based on our Pugh chart, we would screen out the Maximum Arte and She’ll Do options because
they were worse than our reference bridge. Note that it was assumed that the wooden bridges
would be more visually intrusive than the steel bridges because a wooden bridge of the same
strength and span as a steel bridge would require larger members and a larger truss, which would
contribute to visual bulk and might create backlash.
166
Appendix L2.2: Rating Scales
We chose to use a five-level rating scale because we don’t have much information on how these
options differ. A three-point scale is informative enough for our purposes, but without more data
a finer scale isn’t worth much. The meaning of each number is given in the rubric below. A 5
represents the best possible rank in that category and a 1 the worst. All ratings were given
relative to a theoretical steel Pratt truss bridge because we felt much more comfortable relating
our options to a given bridge than trying to figure out where our options fell on more absolute
scales. (Easier to say “this is lighter than a steel Pratt truss bridge - give it a 1” than “this is
relatively light considering the vast array of non-truss options for a pedestrian bridge of this
span...give it a 2 probably?”)
Table L3: Five Point Weighing Scale Rubric
5 ★★★★★
4 ★★★★
3 ★★★
2 ★★
1 ★
Abutment Impact
Significantly less
impact than steel
bridge with low
wind loading.
Somewhat less
impact than steel
bridges with low
wind loading.
Average impact to
steel bridge with
low wind loading.
Somewhat greater
impact than steel
bridge with low
wind loading.
Significantly greater
impact than steel
bridge with low
wind loading.
Carbon Footprint
Significantly smaller
carbon footprint
than steel Pratt truss
bridge
Somewhat smaller
carbon footprint
than steel Pratt truss
bridge.
Average carbon
footprint for steel
Pratt truss bridge
Somewhat larger
carbon footprint
than steel Pratt truss
bridge.
Significantly larger
carbon footprint
than steel Pratt truss
bridge
Construction Cost
Significantly
cheaper than cost of
steel Pratt truss
bridge.
Somewhat cheaper
than steel Pratt truss
bridge.
Average cost of
steel Pratt truss
bridge.
Somewhat more
expensive than the
steel Pratt truss
bridge but still
reasonable.
Significantly more
expensive than steel
Pratt truss bridge.
Maintenance Cost
Very little
maintenance over
the life of the bridge
Sporadic required
yearly upkeep that
add to the costs of
the bridge
Regular
maintenance
required thus adding
cost Requires consistent
yearly upkeep
Excessive
maintenance
required thus greatly
increasing costs
Visual Weight
Minimally intrusive
bridge, very classic
New England look.
Low profile.
Minor intrusion in
the space as design
is slimmer and
blends with region
architecture
Intrudes moderately
on the space but
does have more
New England Style
accents
Intrudes on the
space but is slim and
more minimalist in
appeal
Intrudes
significantly on the
space (bulky or out-
of-place looking
bridge).
Interactive Potential
Ample space on the
bridge that allows
for art installation or
appropriate scenic
lookouts
Moderate space
available for
installation of
community pieces
And moderate
lookout potential
Some space
available for
installation of
community art
pieces and lookout
specification
Minimal space
available for art
pieces and no
particular scenic
lookout
Little-to-no space
available for
community art
works and no
particular scenic
lookout
167
Appendix L2.3: Weighted Criteria
Table 13: Selection Criterion Weights
Selection Criteria Weight
Abutment Impact 0.25
Carbon Footprint 0.075
Construction Cost 0.20
Maintenance Cost 0.20
Visual Weight
0.20
Interactive Potential 0.075
Sum Weight 1
The matrix above details the weight of each criterion deemed most appropriate by the team. As
seen, abutment impact was rated most important considering it is the measure of safety that
ensures the entire structure does not fail. Costs (both construction and maintenance) were
weighted with equal importance because the budget imposes a constraint on the design of the
bridge. Visual weight was weighted the same as the costs because our key stakeholders
considered the visual appeal and simplicity of the bridge in the context of the river as very
significant. While the carbon footprint of the project is important, unfortunately it was not
weighted significantly higher than any other design criterion due to the fact that carbon footprint
is simply a minor consideration. In the same vein, interactive potential was also a minor
consideration because the entire bridge serves the purpose of allowing for community interaction
with the surrounding environment.
168
Appendix M: Superstructure Design Analysis - Dimensional Calculations
Appendix M1: Loads and Hand Calculations for Beam Sizing
Smith Design Clinic/KL&A
CTM NOPS/MRGI Mill River Bridge
Truss Geometry
SK - 1
Apr 27, 2021 at 11:13 AM
210303 Bridge v1.r3d
Y
XZ
Section Sets
Top Chord
Bottom Chord
Vert
Diag
Appendix M2: Finite Element Analysis - Created by Technical Liaison Catherine Mulhern
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeDead LoadSK - 2Apr 27, 2021 at 10:53 AM210303 Bridge v1.r3d-.1k/ftYXZLoads: BLC 1, DL
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeUniform Live LoadSK - 3Apr 27, 2021 at 10:54 AM210303 Bridge v1.r3d-.45k/ftYXZLoads: BLC 2, uniform LL
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeSnow LoadSK - 4Apr 27, 2021 at 10:54 AM210303 Bridge v1.r3d-.15k/ftYXZLoads: BLC 3, SL
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeLive Load - Truck at Mid-pointSK - 5Apr 27, 2021 at 10:55 AM210303 Bridge v1.r3d-2k-8kYXZLoads: BLC 5, Truck - mid
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeLive Load - Truck at EndSK - 6Apr 27, 2021 at 10:56 AM210303 Bridge v1.r3d-2k-8kYXZLoads: BLC 6, Truck - end
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeLRFD Utilization (Uniform Live Load)SK - 7Apr 27, 2021 at 10:59 AM210303 Bridge v1.r3dYXZCode Check( Env )No Calc > 1.0.90-1.0.75-.90.50-.75 0.-.50
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeDeflected Shape for Uniform Live LoadSK - 8Apr 27, 2021 at 11:00 AM210303 Bridge v1.r3dYXZResults for LC 9, LL
Smith Design Clinic/KL&ACTMNOPS/MRGI Mill River BridgeUnfactored Reaction (DL+0.75LL+0.75SL)SK - 9Apr 27, 2021 at 11:03 AM210303 Bridge v1.r3d44.444.4YXZResults for LC 8, IBC 16-11 (b) Y-direction Reaction Units are k and k-ft
190
Appendix N: Visuals - GIS Maps
Appendix N1: Current/Final Maps
Figure N1: Existing path and important existing landmarks.
Figure N2: Existing path with landmarks and areas of concern mapped out.
191
Figure N3: Slope Concern - A.
Figure N4: Slope Concern - A Solution.
192
Figure N5: Slope Concern - B.
Figure N6: Drainage Concern.
193
Figure N7: Slope Concern - C Solution.
Figure N8: Slope Concern - D.
194
Figure N9: Shared use path to pedestrian bridge connection.
Figure N10: New proposed path.
195
Figure N11: Shared use path with 10ft. buffer near the agricultural fields.
196
Appendix O: Visuals - Footing CAD Designs
O1: Sheet 5 - Annotated footing and bridge complete super structure.
197
O2: Sheet - 6 Complete bridge superstructure.
198
O3: Sheet 7 - Annotated footing details.
199
Appendix P: Visuals - Superstructure CAD Designs & Drawings
P1: Sheet - 1 Truss and truss height dimensions.
200
P2: Sheet 2 - Safety railing dimensions.
201
P3: Sheet 3 - Front view of the bridge.
202
P4: Path plan view.
203
P5: Preliminary bridge superimposed over natural site location.
P6: Final bridge cross section view.
204
P7: Final front view visual.
205
Appendix Q: Brief Ecological Impacts
Appendix Q1: Permitting
When attempting to build a new trail, conduct new activity on an existing one, or add structures
like bridges to said trail in the Commonwealth of Massachusetts, there are three stipulations that
must be considered before any proposed project may proceed. First, it should be checked
whether the activity in the area is either 100 feet from a wetland or within 200 feet of a stream or
river. Then, the area should be checked to see whether it is considered a Priority Habitat or not.
In addition, an archaeological assessment may be required for any activity that disturbs the soil
near the river (e.g., the bridge abutments). Finally, if the project has been funded by the state or
federal government, it is essential to know if the activity will be disturbing any soil. Should any
of these three stipulations hold true for the activity within the proposed area, various
corresponding forms will need to be filed in order to proceed. Figure Q1 displays these
stipulations and their next steps in a simple checklist from the Department of Conservation and
Recreation in Massachusetts.
Figure Q1: Checklist of the permitting authorities that may have jurisdiction over a project in
Massachusetts.
In this project, all of the check boxes seen in Figure Q1 would be marked “Yes.” Sections 4.3.3a
and 4.2.2b will go into more detail about how this project is affected by the Wetlands Protection
Act as well as its distinction as a Priority Habitat Area. The third checkbox is not discussed in its
own section because there are not many details to add besides filing a Project Notification form
206
with the Massachusetts Historical Commission. However, it should be noted that because this
area is of high historical importance, there will most likely need to be an archaeological survey
done before complete soil disturbance and construction begins.
Appendix Q2: Wetlands Protection Act
In 1972,28 Massachusetts created the Wetlands Protection Act (WPA) which designated many
natural areas all over the Commonwealth as wetlands. These wetlands typically contain sensitive
ecology, native species, and natural resources that need protection. Any time there is a proposed
activity in or nearby one of these areas, the Conservation Commission must review the project to
see if the area is under the WPA jurisdiction, and if so, determine whether the activity will be
harmful to the sensitive area. In this case, the area this project is hoping to take place in,
specifically the proposed bridge site, is approaching part of land that is considered wetland.
The map depicted by Figure Q2 shows a GIS map from the MassDEP Wetland and Wetland
Change Areas Map that clearly marks elements like shorelines, vernal pool, and most
importantly, apparent wetland limits. As demonstrated, the proposed bridge site is near a
designated wetland outlined in green. This area, of course, is definitely going to be within 200
feet of a river as it is a bridge to cross it, but it is made even more clear by its proximity to the
Mill River outlined in blue. It is important to note that proximity to the wetland is significant but
one cannot overlook the importance of the proximity to the river. Ensuring that the river is
significantly protected from any extensive ecological alterations is the project priority, therefore
protecting the river in turn protects any designated wetlands.
28 https://www.maccweb.org/ Accessed 10/21/20
207
Figure Q2: GIS map of the regions around the river recognized as wetlands in lime green should
be considered during the permitting process of construction in later stages of design
implementation.
Appendix Q3: Priority Habitat
Similar to the WPA, there are areas in the Commonwealth called Priority Habitat Areas that are
protected by certain laws and regulations (Figure Q3). According to the MassGIS Mapping
Tool, most of the area the project revolves around is within the limits of a protected habitat area.
This distinction requires a Massachusetts Endangered Species Act (MESA) Review Checklist
filed through the Massachusetts Natural Heritage and Endangered Species Program (NHESP).
208
Figure Q3: Outlined regions surrounding the Mill River that are recognized as protected areas
that should be protected and considered for the permitting process and later design
implementation.
Appendix Q4: Agricultural Land
Regulation on development occurring in close proximity to agricultural lands is in place to
ensure that construction does not infringe on the right to farm for any residents of the
Commonwealth of Massachusetts as described in the Right to Farm By-law in Article 97 of the
Massachusetts Constitution 29. Oversight of this project can happen with the aid of local authority
groups like the Agricultural Commission of Northampton, a member of the Massachusetts
Association of Agricultural Commissions and the Massachusetts Farm Bureau. Their primary
tasks as a commission include “1)facilitating the pursuit of agriculture, 2)promoting agriculture
based economic opportunities, 3)mediating, advocating, educating, and/or negotiating on
farming issues, 4)advocating for preservation of prime agricultural lands, 5)researching
initiatives to create a sustainable agricultural community, and 6)coordinating the license of city
agricultural land”30. Massachusetts is adamant at ensuring that local land holders maintain their
autonomy and in consistent production through the provision of subsidies and other funding
opportunities like the Agricultural Preservation Restriction Program 31. While there are local
commissions that maintain agricultural lands from being developed, it is important to note that
29 http://www.massagcom.org/agcoms/WestportRTF.pdf
30 https://www.northamptonma.gov/196/Agricultural-
Commission#:~:text=About%20the%20Agricultural%20Commission&text=Facilitates%20the%20pursuit%20of%2
0agriculture,preservation%20of%20prime%20agricultural%20lands 31 https://www.mass.gov/service-details/agricultural-preservation-restriction-apr-program-details
209
the area in which the project will take place should be considered a farm as defined by the
Commonwealth of Massachusetts in order to fall under conservation regulations. As of now,
much of the foreseen development does not surpass the boundaries of the agricultural fields near
the Mill River. Overall other planning and conservation efforts should refer to sources like the
Conservation and Land Use Planning under Massachusetts’ Chapter 61 Laws for further
guidance on how to protect agricultural lands in proximity to recent developments 32.
32 https://masswoods.org/sites/masswoods.net/files/pdf-doc-ppt/Mount_Grace_Ch61_Info.pdf
210
Appendix R: Cost Analysis
This appendix aims to provide more description on how the given prices were estimated in the
cost estimate.
First, for the shared use path, many of the values came from a Northampton Department of
Public Works 33 project that contained an itemized list of materials costs. The hot mix asphalt and
hot mix asphalt base course estimated prices were adjusted for inflation and used for this
project’s needs. The cut and fill price was found using general information found on
HomeAdvisor.34 The drainage solution came from a vegetated swale estimate from a public
works website.35 Finally, the vegetation removal estimate was obtained from the 2017 Site Work
& Landscape Costs 36 textbook, adjusted for inflation.
As for the bridge, every estimate except for the Douglas Fir, geotechnical tests, and crane
estimates came from the Washington State Department of Transportation 37 resource for
quantities, costs, and estimates when building a pedestrian bridge. These estimates were also
adjusted for inflation. The Douglas Fir 38 and crane 39 estimates came from private sellers while
the geotechnical tests estimate came from Site Work & Landscape Costs.
33 http://archive.northamptonma.gov/WebLink/DocView.aspx?id=598116&dbid=0&repo=CityOfNorthampton Last
Accessed 4/29/21. 34 https://www.homeadvisor.com/cost/landscape/excavate-
land/#:~:text=Cut%20and%20fill%20runs%20anywhere,leveling%20terrain%20for%20a%20road Last Accessed
4/29/21. 35 http://www.malvern.org/wp-content/uploads/2013/03/vegswale.pdf Last Accessed 4/29/21.
36 Hale, Derrick. Site Work & Landscape Costs. 2017. Last Accessed 4/29/21.
37 https://www.wsdot.com/publications/manuals/fulltext/M23-50/chapter12.pdf Last Accessed 4/29/21.
38 https://www.woodboardsandbeams.com/timbers Last Accessed 4/29/21
39 https://www.bigrentz.com/blog/crane-rental-cost Last Accessed 4/29/21.
211
Appendix S: Drainage Matrix
NOPS/MRGI Created by:RP, KG
5/1/2021 Status:Complete Preliminary Cost Analysis Tool
Preliminary Cost Estimate
Shared-Use Path Path References
Units Amount/Quantity Researched Price per unit Cost
https://driveways.promatcher.com/cost/massachusetts.aspx
http://enginemechanics.tpub.com/14081/css/Plant-Mix-Construction-469.htm
Cost Per Unit:Hot Mix Asphalt tons 2045 $131.39 $268,683.05
Hot Mix Asphalt Base Course tons 2,045 $118.25 $241,812.70
Cut and Fill - Concern B, C, D yd^3 10,126 $15.00 $151,890.00
Drainage Issue Solution ft 130 $8.50 $1,105.00 path length = 6254 ft
Vegetation Removal Acres 1 $13,642.59 $13,642.59 path width = 10 ft
Drainage Issue Labor cost $/hr 120 $20.00 $2,400.00 depth of mat = 5 in
Total Cost =$679,533.34 tons = 1902.258333
Total Cost with a 25% Contingency Added = $849,416.68 waste factor = 142.669375
Pedestrian Bridge Total Tons required =2045
Units Amount/Quantity Researched Price per unit Cost
Costs Per Unit: Steel Truss (Pre fab)ft^2 1300 $450.00 $585,000.00
Douglas Fir (decking)board feet 6552 $3.50 $22,932.00
Concrete Footing yd^3 51 $700.00 $35,700.00
Steel Railing linear ft 260 $100.00 $26,000.00
Shoring Excavation ft^2 180 $22.00 $3,960.00
Excavation (Eath + Rock)yd^3 740 $220.00 $162,800.00
Geotechnical Surveys linear ft 1080 $101.00 $109,080.00 Bridge References
Crane Service $/day 30 $1,000.00 $30,000.00
Steel Girder ft^2 260 $330.00 $85,800.00
Truss https://concrete.promatcher.com/cost/massachusetts.aspx
Total Cost = $1,061,272.00
Top Chord 140', HSS, 12'x6', .5" wall
Total Cost with a 25% Contingency Added = $1,326,590.00 Bottom Chord 130', HSS, 10'x6', .5" wall http://www.excelbridge.com/for-engineers/cost
Vertical Nodes HSS, 3'x3', .25" wall
Total Preliminary Project Cost Diagonal Beams HSS, 3'x3', .25" wall https://www.dot.state.mn.us/stateaid/bridge/docs/cy2011bridgecostreport.pdf
Total Project Costs = $2,176,007 1 board of douglas fir = 42 board feet 6552
Footing Volume
(one side)680 ft^3
Bridge Dimensions for calcs:
150kips/ft^3 = 102,000 lbs 130' x 10' = 1300 ft^2
CITES (KARENA)
https://porch.com/project-cost/cost-to-backfill-a-trench
http://archive.northamptonma.gov/WebLink/DocView.aspx?id=598116&dbid=0&repo=CityOfNorthampton
https://porch.com/project-cost/cost-to-set-concrete-formwork#:~:text=The%20national%20average%20materials%20cost,range%20of%20%24764.78%20to%20%24926.14.
Adjust the prices based on what the links from Wayne say.
Add and adjust the price for all of the things that Professor Rubin suggested
https://www.bigrentz.com/blog/crane-rental-cost
https://www.usinflationcalculator.com/
Table S1.Matrix outlining solutions to the drainage concern along the path near the agricultural fields
Solution Advantages Disadvantages Reference Image
Culvert ●Directly
addresses and
drains excess
fluid that may
puddle during
heavy rain
events
●Exposure of
infrastructure can
negatively impact
aesthetic of the
region as a result of
continual erosion
●High opportunity for
ecological disruption
at installment
●Inadequate sizing
can result in flooding
and potential path
failure1
Figure 1. Culvert in Greenfield, MA currently undergoing construction1
Permeable
Pavement
●Supports fluid
drainage in
the region that
can help
reduce the
splashing
zones in
regions of
concern after
higher rainfall
events
●Cost is about
20-25% times as
expensive as regular
asphalt2
●Consistent
maintenance like
vacuuming required
to ensure porosity is
maintained2
2 http://www.pvpc.org/sites/default/files/files/PVPC-Porous%20Asphalt.pdf
1 https://www.recorder.com/Hawley-Leyden-garner-culvert-replacement-grants-36280921
●Actively treats
drainage of
the water and
has the
potential of
removing
solids,
pathogens,
hydrocarbons,
and other
contaminants2,
3
●30 year life
span
compared to
traditional 15
year life span
of regular
asphalt2
Figure 2. Typical permeable pavement schematic3
3
https://www.sciencedirect.com/science/article/pii/S0360132306004227?casa_token=rqxk8Icb_cAAAAAA:DRZ8UZ32Vp04Tbe0dF0goTxMW_dEL
QNhKxqC7MLkLsFkwM5mcmaxbcRDhgvIf0HJ3pzq4Y_Zbg
Cross Slope ●2% permitted
cross-slope
grading in
Massachusetts4
can facilitate
runoff flow off
the path to
prevent on-path
puddling
●Maintenance is
required to ensure that
the permitted cross
slope grade is
consistent
●Potential for
uncomfortable bike
riding
Figure 3.Geometric design of varying cross slopes for highway design5
5 https://www.slideshare.net/junaidahmed3192479/geometric-design-of-highway-79804785
4 https://www.mass.gov/files/documents/2018/03/07/e-12-005.pdf
Vegetated
Swale/Rain
Garden
●Reduces the
erosion from
the runoff by
reducing the
velocity of the
discharge6
●Removes
various
particulate
pollutants in
the discharge as
well
●Pretty low cost
and low
maintenance so
as long the
vegetation is
successfully
propagated
●The largest
disadvantage of
incorporating this
method is that
individual trees in the
region of
implementation cannot
be salvaged and older
trees6
Figure 4.Typical cross-section of an implemented vegetated swale7
7 https://www.stormwaterpa.org/assets/media/BMP_manual/chapter_6/Chapter_6-4-8.pdf
6 https://www.mass.gov/doc/complete-erosion-and-sedimentation-control-guidelines-a-guide-for-planners-designers-and/download
215
Appendix T: Legislative Presentation
Feasibility Study of the
Northampton State Hospital
Shared-Use Path
Karena Garcia ✦ Barb Garrison ✦ Ruth Penberthy ✦ Christian Madrigal
Smith College Design Clinic 2020-2021
4/30/2021
Current Northampton Bike Path Network
The red box surrounds
the region where the
proposed shared use
path and pedestrian
bridge would be
developed.
Note, how the area
boxed currently lacks
extensives routes and
shared use paths.
Proposed Path Route
Proposed Path Route
This site is located near a
drainage concern and the
Village Hill residential
complex. This section of the
path would need to be
re-graded as the current
estimated grade is 6.34%,
non compliant with ADA.
As a solution, cut and fill is
proposed as the re-grading
technique for this site. The
adjusted path grade and
paving would provide better
access for all local
community members.
Proposed Path Route
This site is also located
near the Village Hill
residential complex and the
main concern in this region
includes non compliant
4.5% ADA grading. A 10
meter segment along this
path section has a 6.1%
grade. To address this
inaccessibility, this region
would also be a great
candidate for cut and fill.
Along with re-grading this
region, railing with signs
can be placed for aesthetic
and safety purposes to
engage passersby with rich
site history.
Proposed Path Route
This site is located in close
proximity to the historic Ice
Pond and is also suggested
this site be reassessed. Non
compliance with the 4.5%
grading threshold is once
again the main concern in
this region. It is estimated
that the current grade is
slope is about 4.77%. This
non compliant grade can also
be adjusted with cut and fill.
Similarly to the previous
location, this site could
further immerse pedestrians
with signage to contextualize
the space. Additionally, railing
could be used as a safety
measure for users apparent
erosion sites.
Proposed Path Route
This path segment is several
meters from the proposed
bridge site. This section
would be paved to provide
both pedestrian and cyclist
access to the path network.
Most importantly, signs would
be added to further
distinguish the proposed
shared use path from other
local trails.
Bridge Superstructure Concept
Overview of Process Towards Implementation
➔Attain approval from local authorities and commissions, along with state
authorities such as Senator Jo Comerford
➔Submit an application to Public Works at the Northampton Office of Planning
and Sustainability
➔Submit permitting applications and fees for the proposed project
➔Pay fees to cover costs associated with protective gear for construction
provided by the City of Northampton
Photographs by Bailey Ryer Southgate
Current Wireworks/Bridge Site
Smith College - Landscape Studies
Department
In a broad-scale design and planning studio co-taught by professors Reid Bertone-Johnson
and Gaby Immerman, students were asked to design an intervention at the old “Wireworks”
building on Federal Street in Northampton that would increase access to the Mill River and
greenway.
The following slides include a sample of the various projects completed in the course and
serve as examples for the vast opportunity and potential that Wireworks building has.
Reimagining the Wireworks building with these proposals alongside the conceptual design
for the expanded shared use path and pedestrian bridge give a complete look into how this
section of the Mill River could be completely transformed and revitalized. With these
designs, we hope to engage with our community and welcome them into the landscape.
_______________________
Reimagining Wireworks
Credit Author
“Skatepark at the Wireworks”
Tillie Schneiderman, Smith College ‘22
“Skatepark at the Wireworks”
Tillie Schneiderman, Smith College ‘22
“Skatepark at the Wireworks”
Tillie Schneiderman, Smith College ‘22
“Wireworks Recreation Center”
Madison Biasin, Smith College ‘21
Example of an arcade space
layout for along the first
floor walls to allow for more
than just sports to be played
within the Recreation
Center.
Example of mesh curtain
dividers between courts
to allow walkways, keep
the area open and airy,
and to allow for
spectators to watch
across multiple courts at
once.
Examples from Forekicks Sports Complex in Marlborough, MA.
“Wireworks Recreation Center”
Madison Biasin, Smith College ‘21
The upstairs cafe will provide a
hangout space for students to gather
and get some food while being able to
do homework after school together.
This will also provide a space for
parents to gather if it was used as a
tournament space for sports teams.
Couches and tables provide
plenty of indoor seating for
hanging out, homework
sessions, and eating.
Counter placed just as you
walk in to make ordering
convenient for those coming
in to stay and those ordering
to go.
Outdoor
seating out
this way.
“Wireworks Recreation Center”
Madison Biasin, Smith College ‘21
Outdoor cafe seating for
the warmer seasons and
the fencing keeps those
on the rooftop safe and in
the respected area.
Picnic tables give a fun outdoor feel, while
the couches and roundtables give an
additional piece of comfort and
togetherness.
Big windows and glass
doors allow for connection
to those indoors, and
additional lighting can be
added for night use.
“Wireworks Recreation Center”
Madison Biasin, Smith College ‘21
Rooftop garden gives an educational experience
for students to learn how to grow any flower,
fruit, or vegetable all while overlooking the Mill
River.
The access
d
o
o
r
s
open up fro
m
t
h
e
upstairs edu
c
a
t
i
o
n
a
l
room provi
d
i
n
g
e
a
s
y
access when
studying.
Proximity and access to
the Mill River provides
perfect segway into
education about the
history of the area and
the river.
“Wireworks Recreation Center”
Madison Biasin, Smith College ‘21
“Indoor Farmers Market & Garden”
Andrea Gomez, Smith College ‘23
“Indoor Farmers Market & Garden”
Andrea Gomez, Smith College ‘23
“Indoor Farmers Market & Garden”
Andrea Gomez, Smith College ‘23
“Indoor Farmers Market & Garden”
Andrea Gomez, Smith College ‘23
Proposed Project Impacts
Increased access to proposed bridge site
through the proposed shared use path
demonstrates potential to increase local
property values
Walk, Transit, and Bike Score data are measured
on a scale of 0-100 and measure access to
walking routes towards destinations, measure
transit accessibility, and measure bikeability of a
region, respectively [1]. Currently, these values for
the Wireworks Site are 24, 19, and 47,
respectively, and this project is expected to
increase these values by increasing overall
access to this region of Northampton [2]. Data
like these are used by local economists, realtors,
and other property managers to determine
property values as they have been linked to
increase overall land value [3].
Legitimizing this shared use path as part of
the existing path network holds promise for
efficient access to Federal Street from other
sites like the Smith College Athletic Fields
Currently it takes an estimated 19 minutes to
reach the Wireworks Site by foot and 5 minutes
to bike according to Google Maps. Paving the
proposed shared use path and incorporating the
bridge is expected to cut down both of these
times significantly.
Overall
destinati
on
As you can see, the
statistics are evidence
that all of these things can
be realized altogether by…
A pedestrian bridge!!!
Also what better way to
get people on that
pedestrian bridge than by
paving a super easy and
beautiful path that leads
you there!
References
[1] https://www.walkscore.com/professional/research.php
[2] https://www.walkscore.com/score/122-federal-st-northampton-ma-01062
[3] https://nacto.org/docs/usdg/walking_the_walk_cortright.pdf
Z%
NHS Students Ride
their bike to School