Silver Line Extension
Alternatives Analysis
FINAL REPORT
February 2024

Table of Contents

ACKNOWLEDGEMENTS
The Silver Line Extension Alternatives Analysis was conducted by the Massachusetts
Department of Transportation’s (MassDOT’s) Office of Transportation Planning (OTP) and theMassachusetts Bay Transportation Authority (MBTA).
Kat Benesh

Melissa Dullea

Chief of Operation Strategy, Policy & Oversight, MBTA

Senior Director of Service Planning, MBTA

Doug Johnson

Wes Edwards

Project Manager, MassDOT

AGM of Service Development, MBTA

Executive Summary .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . vi
Introduction .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1Project Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Project Need.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 1Relevant Previous Planning Efforts. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 3Public Outreach. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4Study Area .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 4Existing Conditions.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6

A special thank you to the following members of the Working Group that shaped this study:

Demographic Characteristics .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 6

Joseph Boncore

Adrian Madaro

Zoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10

Massachusetts State Senate (through 09/21)

Massachusetts State House of Representatives

Anticipated Future Growth. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10

Mike Connolly

Joseph McGonagle

Transit Service and Access Conditions .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11

Massachusetts State House of Representatives

Massachusetts State House of Representatives

Silver Line 3. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 16

Sal DiDomenico

Aaron Michlewitz

Pedestrian and Bicycle Conditions .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 17

Massachusetts State Senate

Massachusetts State House of Representatives

Traffic Conditions. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 18

Patricia Jehlen

Daniel Ryan

Environmental and Public Health Conditions .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 20

Massachusetts State Senate

Massachusetts State House of Representatives

Alternatives Analysis.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 22

Jay Livingstone

Screening Against Project Purpose.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 25

Massachusetts State House of Representatives

Tier 1 Evaluation .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 25
Tier 1 Evaluation Results.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 30

Maria Belen Powers

Travis Pollack

Tier 2 Evaluation .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 32

Executive Director, GreenRoots

Senior Transportation Planner, MAPC

Tier 2 Evaluation Results.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 39

Todd Blake

Susanne Rasmussen

Director of Traffic and Transportation, City of Medford

Director of Environmental and Transportation Planning,
City of Cambridge

LPA Alignment. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 45

Brad Rawson

Basis for the LPA. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 54

Eric Bourassa
Director of the Transportation Division, MAPC

Vineet Gupta

Director of Transportation and Infrastructure,
City of SomervilleDirector of Planning, City of Boston Transportation
Department

Julia Toof

Alexandra Kleyman
Senior Transportation Planner, City of Somerville(through spring 2022)

Jay Monty
Director of Transportation and Mobility, City of Everett

Locally Preferred Alternative.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 43
Service Characteristics .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 53
Next Steps.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 57

Somerville Pedestrian and Transit Committee

Alexander Train
Director of Housing and Community Development,
City of Chelsea

Julia Wallerce
Boston Program Manager, ITDP

MassDOT contracted a consultant team to support this effort:
Nelson Nygaard in partnership with: McMahon Associates, Regina Villa Associates (RVA),RKG Associates, Steer Engineering, HMMH, and Central Transportation Planning Staff (CTPS)MBTA Silver Line Extension Project Final ReportiFigures
Figure 1 | Silver Line Extension Alternatives Analysis Study Area.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 5Figure 2 | 2018 Employment and Population Composite Density .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 9Figure 3 | Study Area Zoning. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 10
Figure 4 | Ratio of Weekday Off-Peak to Peak Bus Boardings. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 12
Figure 5 | Daily Passenger Minutes in Delay .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 13
Figure 6 | Transit Access to Glendale Square .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14
Figure 7 | Transit Access to Bellingham Square. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 14
Figure 8 | Transit Access to Everett Square.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15
Figure 9 | Transit Access to Sullivan Square .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 15
Figure 10 | Silver Line Extension Alternatives Analysis Evaluation Process. .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 22
Figure 11 | Section 1: Chelsea Station or Glendale Square to Sweetser Circle in Everett.  .  .  .  . 26
Figure 12 | Section 2: Sweetser Circle to the Orange Line. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 26

TablesTable 1 | Project Goals and Objectives .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 2Table 2 | Study Area Demographic Comparisons .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 8Table 3 | Preliminary Concepts .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 23
Table 4 | Goals and Tier 1 Metrics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 28
Table 5 | Tier 1 Concepts advanced to Tier 2 Evaluation.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 30
Table 6 | Goals and Tier 2 Metrics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 38
Table 7 | Performance of SL3 Extension Alternatives. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 39
Table 8 | Performance of SL6 Alternatives .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 41
Table 9 | LPA Key Statistics. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 43
Table 10 | SL3 Assumed Levels of Service .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 53
Table 11 | Metrics and LPA Findings.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 54

Figure 13 | Section 3: Orange Line to Kendall Square.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 27
Figure 14 | Section 4: Orange Line to Downtown Boston .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 27
Figure 15 | Tier 1 Five-Point Scale. .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 28
Figure 16 | All Tier 1 Concepts.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 31
Figure 17 | SL3 Extension Alternatives .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 32
Figure 18 | Alternative 1: SL3 to Malden Center .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 33
Figure 19 | Alternative 2: SL3 to Wellington.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 33
Figure 20 | Alternative 3: SL3 to Sullivan.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 33
Figure 21 | SL6 Alternatives .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 34
Figure 22 | Alternative 4: SL6 to Kendall via McGrath .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 36
Figure 23 | Alternative 5: SL6 to Kendall via Rutherford.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 36

APPENDIX
Appendix A: Public Outreach Summary
Appendix B: Existing Conditions
Appendix C: Silver Line Extension Alternatives Analysis Screening
Appendix D: Tier 1 Evaluation Methodology Memo
Appendix E: Tier 2 Evaluation Methodology Memo
Appendix F: Additional Transit Projects for Inclusion in the CTPS No Build 2040 Model
Appendix G: Busway Extension Concept Drawing

Figure 24 | Alternative 6: SL6 to Boston via Rutherford.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 37
Figure 25 | Alternative 7: SL6 to Kendall from Chelsea .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 37
Figure 26 | LPA – Alternative 3: SL3 to Sullivan.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 44
Figure 27 | Proposed Transit Configuration for the LPA -1.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 47
Figure 28 | Proposed Transit Configuration for the LPA - 2 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 47
Figure 29 | Proposed Transit Configuration for the LPA -3.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 48
Figure 30 | Proposed Transit Configuration for the LPA - 4 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 49
Figure 31 | Proposed Transit Configuration for the LPA - 5 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 51
Figure 32 | Proposed Transit Configuration for the LPA - 6 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 52

ii

MBTA Silver Line Extension Project Final Reportiii

Executive Summary
The purpose of the Silver Line Extension
Alternatives Analysis (SLXAA) project has
been to explore the feasibility and utilityof various corridor and service options toextend the Silver Line 3 from its current
terminus in Chelsea through Everett and on
to Somerville, Cambridge and/or Boston.
The primary recommendation from thisstudy is to extend the Silver Line to the
Sullivan Square MBTA station, providing aconnection to the Orange Line and a dozen
MBTA bus routes. This project is projected
to increase daily ridership on the SL3 by over
15,000 riders, with a full daily ridership of over
27,800 riders, which is higher than many of the
BRT projects in receipt of federal funding andin project development around the country.
Furthermore, this extension will benefit transitdependent riders by increasing frequencies
outside of traditional peak commute hours andexpanding access to an average of 345,000
jobs via a 45-minute transit commute.

The recommended alignment has the potential
to provide transit service with exclusive bus
transit right of way along 80% of the 6 1/3-mile
extension and could be operated with theexisting SL 3 bus fleet, with minimal impact tocurrent service frequency. Other MBTA buses
already in operation along portions of thisalignment, including bus routes 104, 105, and109, could avail themselves of dedicated transit
right of way investment and as a result see a
total of 2.9-minute reduction in travel time delay
per trip on a daily basis. The recommendedalignment traverses three municipalities,
Chelsea, Everett, and Boston, which have been
actively engaged in the SLXAA process, andendorse this recommendation. Due to theirendorsement and the ability of the existing SL3
fleet to serve this extension, implementation is
anticipated to be achievable in a relatively shorttimeframe.
This study also assessed the feasibility ofextending Silver Line service beyond theOrange Line. The Alternatives Analysis showeda ridership benefit to providing service to either
Kendall Square or downtown Boston. This
service, referred to as the SL6 in this process todifferentiate it from SL3 extension alternatives,
assumed that the SL3 extension was in place
to Everett Square and produced an additional
20,000-23,000 riders/day1 for alignments to
Kendall Square and 11,000-13,000 riders/day2
for alignments to downtown Boston.
While extending Silver Line service beyond
the Orange Line to either Kendall Square or
downtown Boston provides potential ridershipbenefits, further study and the completion of
ongoing planning efforts by others is required
to determine the feasibility of implementing a
Silver Line service to either location. Moreover,this study found that procuring additional
Silver Line vehicles, and expanding vehicle
maintenance and storage capacity would be
required. A future study should consider thefollowing:•

The ridership analysis should model thepotential ridership using the Redesigned
Bus Network that is currently being
implemented by the MBTA;•

Further work be done on the Rutherford
Ave. redesign effort and the Gilmore
bridge project to better understand thepotential for bus priority lanes withinroadway infrastructure right of way; and•More work be done to evaluate transit
priority initiatives within Kendall squarespecifically.

In the near term, Bus Network Redesign will
implement high frequency bus services fromChelsea to the Orange Line, and Sullivan
Square to Kendall Square, creating theconnections evaluated in this study to build
market demand. Transitioning to Silver Line will
be dependent on future operational resources,
and fleet and on-street capital investments.

1 when compared to the no build.
2 Ibid.	

vi

MBTA Silver Line Extension Project Final Reportvii

Background
MassDOT and the MBTA began the SLXAA
process in 2021. Since that time the agencies
have analyzed dozens of potential operationaland corridor alignment options against a
discrete set of goals and objectives, developedin concert with a Working Group of municipal
and advocacy partners and the general public.
Following an analysis of needs, opportunities,
and constraints, which featured Working Groupdiscussions and a public meeting, MassDOT
developed a universe of potential ideas. These
were then narrowed over a course of threesteps, illustrated below.
The first step broadly screened ideas against
the project purpose, with ideas not meeting the
purpose removed from further consideration.
The second step evaluated concepts at
a geographic scale – organized by logicalbreaking points. The most promising of theseconcepts were combined as end-to-end route
alternatives for the third evaluation step. There
were seven of these shortlisted route-level
alternatives organized into two groups asfollows:

Locally Preferred Alternative•

A set of three alternatives extended
the SL3 to the Orange Line (called SL3
extension alternatives, Alternative 1: SL3
to Malden Center, Alternative 2: SL3 to
Wellington, Alternative 3: SL3 to Sullivan)•

A set of four alternatives that provide
a new service (called the SL6 forevaluation purposes) extending from
Everett into Kendall or downtown
Boston (Alternative 4: SL6 to Kendall via
McGrath, Alternative 5: SL6 to Kendall via
Rutherford, Alternative 6: SL6 to Boston
via Rutherford, and Alternative 7: SL6 to
Kendall from Chelsea)

This final analysis step featured a robust
evaluation including running the CTPS regionalmodel. This work is now complete and results
have been presented broadly to stakeholders
and the public. MassDOT and the MBTA are
now ready to move forward with a LocallyPreferred Alternative (LPA) for SL3 Extension
from its current terminus at Chelsea Station
to the Sullivan Square Orange Line Station(Alternative 3), and recommend further
modeling be done on the SL6 alternatives in
the near future.

Silver Line Extension Alternatives Analysis Evaluation Process

viii

MBTA Silver Line Extension Project Final ReportixKey Statistics
Length of the LPA: 6.36 Miles
Number of Stations: 81
Assumed Span of Service:
4:20 AM-1:15 AM Weekday
4:55 AM-1:45 AM Saturday
5:50 AM-1:50 AM Sunday
Frequency: 10 minutes AM + PM Peak
Assumed Vehicle Load: 65 passengers2
Extent of Operation in Exclusive Transit Rightof-way: 80% (5.18 miles)
Time Spent at Each Station: 24 seconds3
Average Daily Ridership (2040): 27,800
Major Transfer Locations:Chelsea Station
Everett Square
Sullivan Station
Additional Silver Line buses needed: 4 buses
Capital Costs: $95 M
Access to Jobs via 45-minute Transit
Commute:AM Peak: 347,000 jobs
Midday: 344,000 jobs

1 Chelsea Station, 2nd St. at commuter rail ROW, 2nd St. at Spring
Street, Broadway/Everett Square, Broadway at Gladstone St., Lower
Broadway at Beacham, Lower Broadway at Dexter St., Sullivan Square.
2 MBTA Service Delivery Policy, page 47: https://cdn.mbta.com/sites/
default/files/2021-06/2021-service-delivery-policy.pdf
3 All-Door Boarding Pilot on the Silver Line (2017), OPMI Data Blog:
https://massdottracker.com/datablog/?p=154. Assuming front-doorboarding.

The SL3 LPA has been identified as anextension of the existing SL3 service fromits current terminus at Chelsea Station to
the Sullivan Square Orange Line Station.
The primary attributes of this alternative areincluded in Table 1.
This service would operate primarily on
dedicated bus-only lanes along an extended
Chelsea busway, Second Street, Spring Street,
Chelsea Street, Broadway, Lower Broadway,
Alford Street and across the Alford Bridge
to Sullivan Station. There were several key
differentiators between the SL3 Extension
to Sullivan and the other SL3 Extension
alternatives, described in the paragraphs
below.
••

While the existing part-time, side-runningbus lanes on Upper Broadway inEverett have helped eased some of thecongestion during the peak commute
hours along the Broadway corridor,transit users still face tremendous
congestion, amounting to thousands ofdaily passenger minutes in delay between
Chelsea Street and Sweetser Circle
alone.4
The SL3 LPA would provide full-time
dedicated bus lanes along 80% of itsalignment and transit signal priority at
14 intersections, providing travel times
that are faster than drive alone times,
and travel times that are more reliablebecause with dedicated transit lanes the

4 MBTA Winter 2020

Silver Line vehicles are not vulnerable
to the traffic congestion experienced in
the adjacent general-purpose lanes. The
level of transit priority achieved under
Alternative 3 is higher than the other SL3
Extension alternatives.
••

In addition, other local bus routes that
operate along the alignment can benefit
from the bus lanes implemented as partof the SL3 extension. These include the
MBTA Routes 97, 104, 105, 109, 110,
and 112, several of which are among
the MBTA’s highest and most resilient
ridership. On average, the proposed
infrastructure could save its transit riders
3 daily minutes in delay. This is higher
than any of the other SL3 Extension
alternatives. The existing MBTA bus
routes that operate along this alignment
are more likely to serve people of color,
people without access to a personalautomobile, and persons of lower
incomes.
The CTPS Travel Demand Modelestimated that extending the SL3 to
Sullivan could see up to 27,800 daily
boarding by year 2040. This is 15,000
more daily boardings than the SL3
would experience if it were to end at its
current terminus at Chelsea Station – a
120% increase. While some of theseriders would be people who would haveotherwise used local bus routes, ouranalysis shows that extending the SL3 to
Sullivan Station could add up to 11,000
net new daily boardings to the system.

•

There is strong support for therecommended LPA among municipal
leaders as well as from the community
at large. In our third feedback survey,
respondents ranked the LPA as the SL3
extension alternative they would be most
likely to use, ahead of connections to
the Orange Line via Malden Center or
Wellington.

•

The SL3 could be extended to Sullivan
using the existing Silver Line fleet. The
extended service is assumed to operatewith 10-minute headways during most of
the day5 which results in a requirementfor 12 Silver Line vehicles, four morethan what is needed for the existing SL3
service.

While the technical analysis showed that a
BRT capital investment connection between
Chelsea and Sullivan aligned the best with thestudy goals and objectives, pursuing this LPA
would not preclude transit service to Malden
Station and to Wellington Station. In fact, theBus Network Redesign shows a frequent
service route T104 connecting Airport Station
to Malden Center via Everett, and frequent
service route T110 connecting Wonderland to
Wellington vis Everett. As the SL3 extension
moves into project development, additional
refinements could be made to this and other
MBTA bus route begin and end points to best
serve ridership demand.

5 Consistent with SL3 Winter 2020 schedule

The Alford Street Drawbridge provides
an uninterrupted connection between
Everett and Charlestown during most of
the day. It is closed for the passage ofvessel traffic during the morning peak
hours and between 5 p.m. and 6 p.m.
daily and would minimally impact SilverLine operations across the corridor.

x

MBTA Silver Line Extension Project Final ReportxiIntroduction

Introduction
The Silver Line 3 (SL3) plays an important role in the MBTA service network, providing a transit
connection between Downtown Boston, the Seaport, Logan Airport, East Boston, and Chelsea .
Opened in 2018, the SL3 provides bus rapid transit service for much of its route– operating in
exclusive right-of-way in South Boston and Chelsea . Since the opening of the SL3, multiple studies
and plans have recommended extending the service west into Everett and adjacent municipalities .
Everett, Chelsea, Somerville, and Cambridge are important growth centers in the greater Boston
region, experiencing rapid population and employment changes . Strengthening the transit
connections available in the Lower Mystic Region is critical to ensuring transportation challenges
do not constrain growth in the region and that transit services provide sufficient access to job
centers and resources across greater Boston .

The MBTA’s Focus 40 Plan prioritized studying extending the Silver Line beyond Chelsea,
and in 2021 the MassDOT Office of Transportation Planning launched the Silver Line
Extension Alternatives Analysis.
This report summarizes the Silver Line Extension Alternatives Analysis process and outcomes
and describes the Locally Preferred Alternative (LPA) that is recommended for moving into
project development . This report describes which alternatives were studied, the major steps
in the decision-making process, who was involved, and next steps to move the LPA towards
implementation .

Project Purpose
The purpose of the Silver Line Extension Alternatives Analysis was to assess the feasibility, utility,
and cost of various alignment and service frequency options of an extension of the Silver Line,providing high quality transit from Chelsea through Everett and on to Somerville, Cambridge, and/or Boston .

Project Need
This project’s principal objective is to add transit service capacity and connectivity to knit together
Chelsea and Everett with nearby communities that are not currently well connected with highquality transit . Additional needs to be addressed through the Silver Line Extension are:•Existing transit service is not competitive with driving for many types of trips being made to
and from Chelsea and Everett .

•Despite the lack of competitiveness, bus ridership in Chelsea and Everett during the
pandemic has been more durable than in other MBTA-served communities .

•Chelsea, Everett, Somerville, and Cambridge are experiencing rapid growth in housing andemployment in areas that are not currently well served by transit .

•There are existing transit connections in Chelsea, Everett, and nearby communities that could
be leveraged and improved into a high-quality cohesive network .

MBTA Silver Line Extension Project Final Report1Introduction

Introduction

Goals and Objectives

Relevant Previous Planning Efforts

The following five goals and related objectives stem from the project’s Purpose and Need . These
were used to develop evaluation metrics for comparing the alternative transit investment options
for the study area .

Extending Silver Line service beyond Chelsea
to Everett and the surrounding communities
has been studied in the past . Many previous
efforts, including the Urban Ring, the Everett
Transit Action Plan, and the Lower Mystic
Regional Working Group, have developed
recommendations that are relevant to thisstudy . Below, in alphabetical order by authoring
agency, is a summary of these relevant
previous and ongoing planning efforts .

Table 1 | Project Goals and Objectives

Goal Area

Objectives

Expand Mobility
and Access• Optimize potential ridership• Connect residents directly with jobs, services, and other daily activities• Provide reliable transit service at or near rapid-transit levels to communities not currently servedby rapid transit• Provide transit service that takes a similar amount of time or is faster than driving• Maximize new connections with other transit services• Provide transit connections to existing and planned affordable housing• Provide transit service to areas with current or future growth in housing and jobs
• Use investments to improve existing transit services in the study area
• Serve High Demand Areas identified by the Bus Network Redesign effort currently underway

Advance Equity• Optimize potential ridership for transit critical populations• Provide new transit service for people who already rely on transit to get around• Make sure people who are likely to rely on transit have a route that matches how much service
they need and when
• Make improvements to existing transit service used by people who are likely to rely on transit

Improve Safety• Provide safe, comfortable, and accessible bike/pedestrian access to and from stations• Address identified transportation safety issues at intersections along the project corridors

Support Climate
Change Resilienceand Sustainability• Increase transit mode share and reduce dependence on cars for transportation withinstudy area
• Reduce greenhouse gas emissions from single occupancy vehicles within the
study area
• Address climate change vulnerabilities of transit infrastructure

Advance
Feasible and
Implementable
Solutions• Ability to phase alternative over time
• Extent to which alternative provides standalone value of transit service, within this section alone• Ability for alternative to fit within existing roadway footprint• Ability to offer highly reliable bus service• Extent to which investment could be included without other efforts upcoming or currently
underway• Extent of known municipal support for alternative alignment and service assumptions• Minimize the number of major cost items within alternative alignment while maintaining benefit

The City of Boston released Imagine Boston
2030 in 2017, outlining initiatives to support
the City’s future growth such as encouraging
a mixed-use core in the urban center andexpanding transit access for residents andworkers . The City of Boston is also conducting
the Rutherford Avenue/Sullivan Square Design
Project which aims to improve the 1 .4-mile
corridor with measures such as a road diet,transit priority, a two-way bike path andwalking trail, and new pedestrian crossings .
These infrastructure improvements will be
key to unlocking development parcels aroundthe transit station and improving bus transit
reliability along nearby corridors .
The City of Cambridge completed EnvisionCambridge in 2019, the City’s plan for inclusive
and sustainable growth through 2030, with
topics covering climate and environment,
community wellbeing, economy, housing,mobility, and urban form, and advocates for
improved multimodal connections between
Kendall Square and Sullivan Square . Also in
2019, the Kendall Square Association released
Transport Kendall, a plan that seeks to maintainand enhance the transit-oriented development
model in Cambridge, and to promote future
investment in the transit system, focusing on
the Grand Junction Corridor, the Red Line, andbus connections .
The City of Everett put forth the 2016 Everett
Transit Action Plan, which suggested using
service/route improvements, major transit
investments, and adding pedestrian/bikeaccess to provide more transit access andconnection to Boston . Priority corridors fortransit improvements discussed in this plan
include Broadway to Sweetser Circle, Main
Street, Chelsea Street, and Ferry Street .

2

Metropolitan Area Planning Council (MAPC)
published the Lower Mystic Regional Working
Group: Planning for Improved Transportationand Mobility in the Sullivan Square Area in
2019, proposing solutions to traffic congestion
by expanding public transit services . The Lower
Mystic Regional Working Group is a group of
11 public agencies that was established by
the Massachusetts Secretary of Transportation
to assess the impact that new projected
growth in the Sullivan Square area may haveon travel conditions and to identify potential
solutions . The Working Group consists of the
Massachusetts Department of Transportation,
the cities of Boston, Everett, and Somerville,
the Metropolitan Area Planning Council(MAPC), the Executive Office of Housing andEconomic Development, the Massachusetts
Gaming Commission, the Office of the Attorney
General, Massport, the Office of Congressman
Michael Capuano, and Encore Boston Harbor .
In 2017, the Working Group started a two-yearplanning process to improve transportation in
the Sullivan Square area . The process used
quantitative modeling to test eight different
scenarios of infrastructure and policies under
future conditions and resulted in a set ofrecommendations that had transit service
improvements at its core . The Working Group
report identified BRT as a promising option to
reduce vehicle trips and increase connectivity
in Sullivan Square . The report recommended
the construction of two BRT routes thatwould run on a combination of exclusive andpriority lanes . The first recommended route,
Route 1, would build off the SL3’s Chelsea
Station terminus and connect to North Station
via Sullivan Square, using a combination of
dedicated bus lanes and the commuter railright-of-way . The route would travel along
Second Street to Route 16, and then take
Route 16 to Broadway . The service would thentravel along Broadway to Sullivan Square anddown Rutherford Avenue to North Station .
In the final scenario analysis, this route wasprojected to see daily ridership of 27,600 trips .
Route 2 would connect Glendale Square withKendall Square; via Broadway, Sullivan Square,
the new Inner Belt Bridge and Inner Belt, andthen along proposed bus lanes south from
Lechmere on First Street, Binney Street, andMBTA Silver Line Extension Project Final Report3Introduction

Third Street . The construction of a new bridgeconnecting Inner Belt Road and Lechmere
station, and passing over the railroad tracks,
was a key component of this alternative . In the
final scenario analysis, this route was projected
to see daily ridership of 13,400 trips .
The City of Somerville in 2021 released
SomerVision 2040: Comprehensive Plan
Update 2010-2040 to support the conservationof residential neighborhoods, enhance theCity’s squares and commercial corridors, andtransform opportunity areas . The plan, an
update to the previous SomerVision 2030,
featured implementation priorities include
equity, infrastructure investments, reducing
vehicle miles traveled, and sustainability .

Public Outreach
Several comprehensive public outreachactivities were initiated to engage and inform

Introduction

stakeholders and community members about
this project . Due to the pandemic, manyoutreach activities were virtual, with some inperson activities held outdoors where possible .
A wide range of in-person and virtual eventswere organized with different formats including
four virtual public meetings, six virtual working
group meetings, and four pop-up events
throughout the duration of the project .

Figure 1 | Silver Line Extension Alternatives Analysis Study Area

The External Working Group, which included
representatives from the cities in the study
area, MAPC, and the State Legislature,
met five times throughout the planning
process, provided input and collaborated
with the project team to identify and evaluate
alternatives .
Strategies used consistently throughout the
project included regular updates to the SilverLine Extension (MBTA .com/SLX) webpage,
promotion through social media platforms,
management of the SLX@MBTA .com project
inbox to receive and respond to comments
and questions, and email delivery to notify
subscribers about events and project updates .
In addition to hosting both in-person andvirtual events, opportunities for feedback wereavailable via three feedback forms released
throughout the different project phases . Pleaserefer to Appendix A: Public Outreach Summary
for a full overview of all public outreachactivities conducted during this project .

Study Area
The study area for the project is shown in
Figure 1 . It includes sections of Boston,Cambridge, Chelsea, Everett, Somerville, andMedford . It was developed to include previousalignments considered in earlier planning
efforts, with a buffer to reflect uncertainty
and to be open to new ideas that could arise
through public outreach . The original study
area was slightly expanded to capture a
section of Malden, including the Malden Center
Orange Line Station, during the development ofalternatives phase of the project .

4

MBTA Silver Line Extension Project Final Report

5

Existing Conditions

Existing Conditions
The existing and future conditions analysis
provides an overview of the current
transportation infrastructure and service
conditions that affect the movement ofpeople, goods, and services within, to, fromand through the study area. This chapter
summarizes the key findings from a full Existing
Conditions Analysis conducted for the study.
The full Analysis can be found as Appendix B:
Existing Conditions.

Demographic Characteristics
In 20181, the study area was home toapproximately 195,000 residents. As shownin Table 2, Everett and Chelsea have a
combined population of approximately 75,000
and the remaining areas of the study area
have a population of approximately 120,000.
The communities in the study area havethe population and employment density tosupport frequent, all-day transit service. A highpotential for transit ridership in the study area
is illustrated through the composite density(composed of both population and employment
densities) map in Figure 2.
A crucial component of this analysis was tounderstand where the highest concentrationsof transit-critical populations are located andthe specific transportation challenges they face.
Transit-critical populations are those that are
traditionally more reliant on transit, which isdefined by the MBTA as low-income people,
people of color, and people from low-vehicle
households.2 Everett and Chelsea are made upof 66% minority residents and have a higher
proportion of “transit-critical” residents, ascompared to 47% minority residents in the restof the study area and 44% in the Inner Core.
One half of Chelsea and Everett residents are
considered low-income compared to 42% in
the rest of the study area. Everett and Chelsea
1 The existing population and socioeconomic variables are from the 2018
American Community Survey 5-year Estimates, and theexisting employment and 2040 population and employment data are
outputs from Central Transportation Planning Staff’s (CTPS) travel
demand model, the Boston Region Metropolitan Planning Organization(MPO).
2 This study defines low-income as below 60% of area median income;people of color/minorities as all race categories except White
alone (not Hispanic); and low-vehicle households as households withzero vehicles available and households with fewer vehicles thanworkers.

6

have 43% foreign-born residents, compared
to 36% in the rest of the study area. However,vehicle ownership is higher and transit use
rates are lower in Everett and Chelsea than in
the rest of the study area. This is likely because
neither community is served directly by the
rapid transit rail network, unlike neighboring
communities like East Boston and Malden,
which in turn increases the need to rely on avehicle for mobility in Everett and Chelsea. This
also in turn increases the transportation costburden on residents of Chelsea and Everett.

Employment
Communities with high rates of shift workers
and workers without a college degree tend
to have different travel patterns, with moreworkers commuting outside of the traditionalmorning and afternoon peak rush hours. Thiscan make it difficult to rely on public transit
as the primary form of transportation, as
the current MBTA bus system is focused onproviding the most service during weekday
peak-periods, with lower service during offpeak hours and on weekends. This means that
commuters who work non-traditional hours orin areas without convenient transit routes, likein Everett and Chelsea, often have difficultyfinding a transit option that meets their needs.
Even when transit options are available, they
may not run frequently enough to be reliable,or they may require multiple transfers. Thiscan be especially problematic for workers whoneed to arrive at work at a specific time (jobswith a punch-in and punch-out system), as theconsequences of not arriving on time could
mean losing wages or their job.
Only 18% of residents in Everett and Chelsea
age 25 and older have a bachelor’s degree
or higher. In contrast, about 50% of residents
in Cambridge, Somerville, and Charlestown
have a bachelor’s degree or higher, with rates
above 75% in East Cambridge and much ofCharlestown. Everett and Chelsea also have alower proportion (37%) of workers who leave
for work between 7 a.m. and 9 a.m. than the
Inner Core (52%) and the remainder of thestudy area (53%). This indicates that more
Everett and Chelsea residents work jobs with

MBTA Silver Line Extension Project Final Report

7

Existing Conditions

Existing Conditions

varying shifts and schedules, which are notwell served by the existing peak-oriented transit
system. It is therefore crucial to provide highquality transit service all day for workers who
do not work in traditional “9-to-5” positions.

While the MBTA is working to redesign the
Bus Network to provide more frequent,
all-day service, population and employment
demographics in Everett and Chelsea indicatethat rapid-transit service would be heavily
utilized.

Figure 2 | 2018 Employment and Population Composite Density

Total Pop

Pop Density (peracre)

Minority Pop (%)

Below 60% AMI (%)

Zero and low-vehicle
HH (%)

Foreign Born
Population (%)

Population Age 25
and Over with a
Bachelor’s Degree

Workers who Leave
during A.M. Peak (%)

Transit Commuters(%)

Table 2 | Study Area Demographic Comparisons

Study Area

195,416

25

54%

35%

46%

39%

37%

47%

33%

Everett and Chelsea

75,361

23

66%

40%

42%

43%

19%

37%

27%

East Boston

29,470

42

71%

41%

63%

53%

23%

40%

56%

Cambridge,
Somerville,
Charlestown (StudyArea Sections)

90,585

24

40%

31%

44%

31%

56%

57%

30%

Inner Core
Communities2

1,771,225

13

44%

32%

39%

28%

49%

52%

27%

1

Pop = population				
HH = household				AMI = Annual Median Income
Data Source: 2018 American Community Survey 5-year Estimates

1 Sections inside study area, excludes Logan Airport
2 Boston Area Inner Core Communities include Arlington, Belmont, Boston, Cambridge, Chelsea, Everett, Lynn, Malden, Medford, Melrose, Milton,
Needham, Newton, Quincy, Revere, Saugus, Somerville, Waltham, Watertown, and Winthrop

8

MBTA Silver Line Extension Project Final Report

9

Existing Conditions

ZoningZoning provides an indication both of how land
is used and how municipalities wish land to be
used. Both of these are important for identifying
transit-supportive land uses. The current zoning
in the study area1 is diverse, with a significant
share of residential, industrial, and mixed-use
classifications within each city. Approximately
40.5% of the entire study area is zoned as
residential, followed by industrial (20.8%),
mixed-use (16.8%), and commercial (11.3%)
districts. Almost 5% of the study area is zoned
as open space (see Figure 3). Approximately
half of the land area in Cambridge, Chelsea,
Everett, and Somerville is zoned as residential,
whereas this classification makes up only
27.9% of Boston and 19.8% of Medford’s land
within the study area. Mixed-use land is fairly
standard across the study area, accounting for
15 to 20% of land area for each municipality.
Everett (24.9%) and Medford (30%) have thelargest share of industrial zoned land, thoughparts of the Second Street corridor in Everett
have already been planning for transitions tomixed-use neighborhoods.

Existing Conditions

A review of the development adjustments
by municipality indicates that Cambridge is
projected to contribute the highest share ofadditional employment at 47.7%, while Boston
accounts for over half of the additional housing
units (59.2%) and population (57.7%) thatnew developments have or are anticipated togenerate within the study area.
In total, 31,905 jobs, 8,825 housing units, and20,550 residents have been or are anticipatedto be generated by new development projects
within the study area TAZs. Adding these to
the existing 2040 projections, the study area
could have approximately 321,510 residents(11.0% increase), 150,230 housing units (6.2%
increase), and 320,700 jobs (6.8% increase)by the year 2040. These figures are based on
projection trends by MAPC/CTPS continuing
through 2040 and the identified development
pipeline coming to fruition.
Figure 3 | Study Area Zoning

The 2040 regional model was updated with
anticipated development to estimate future
population, household, and employment
growth more accurately within the study area.
This was done by starting with the 2040
regional model and comparing its forecasted
growth with what was known in the 2019
Lower Mystic Regional Working Group study
and what developments are currently includedin the study area municipalities development
pipelines. To be conservative, only development
projects listed as completed, in construction,or permitted and approved were included infuture forecasts. Based on the housing unit
counts and commercial square footages of 88
development projects not included in the 2018
projection, the projected number of employees,
residents, and housing units were calculated
and added to the 2040 projection.2

10

Transit Availability and Ridership
Chelsea and Everett are both served by MBTA
Bus Routes 110, 111, and 112, with an additional
six routes serving Everett only (Routes 97, 99,
104, 105, 106, and 109) and four routes serving
Chelsea only (Routes 114, 116, 117, and theSL3). The Newburyport/Rockport Line provides
commuter rail service to Chelsea Station.
Important transit hubs in the two communities
include Bellingham Square in Chelsea andEverett Square in Everett. In Winter 2020, 23%of weekday bus boardings within the study area
occurred in Chelsea and 12% occurred in Everett.
Combined, this is higher than Cambridge andSomerville, where 26% of boardings took place.
In Winter 2020, Route 111 was the secondhighest ridership route in the MBTA bus system,with nearly 65,000 average weekday boardings.
Routes 104, 105, 109, and 111 are also all within
the top 10 most crowded routes in the network1,
indicating that demand exceeds current service
levels.
Chelsea and Everett have very high ratios ofoff-peak boardings compared to the study
area, meaning that transit demand remains
high throughout the day rather than only during
traditional commute times. On average, stops
in Chelsea and Everett, see 36% and 6% more
off-peak boardings, respectively, than the averagestop in the study area. In turn, Cambridge has
the lowest off-peak to peak boarding ratio in the
study area, indicating that boardings in the city
tend to skew toward peak times. This ratio of
off-peak to peak bus boardings is illustrated in
Figure 4.

Anticipated Future Growth

1 It is important to note that zoning percentages reflected here are not for
the full municipalities of Boston, Cambridge, Chelsea, Everett,Medford, and Somerville – just for the proportion of thosemunicipalities that are within the SLXAA study area.
2 New development projects have either come online or have been
proposed since the regional projections were completed 2018. To
capture their potential impact, the latest real estate development projectTransit Service and AccessConditions

inventory from MassBuilds (December 2020) were collected, in addition
to requesting updated development pipeline information from each cityin the study area and reviewing city websites. An analysis was thenconducted to compare the latest development database with the inputs
that MAPC used in 2018 to produce their projections. The adjustments
to the development database included 88 projects within the study
area’s TAZs.

The highest ridership locations include Bellingham
Square, with 3,600 weekday bus boardings,
which is comparable to Wellington Station. Stops
between Bellingham Square and Chelsea Square
have some of the highest consecutive boardingsin the study area. The 2,640 boardings at 18
stops along the Broadway corridor in Everett arecomparable to Broadway and Highland Avenue inSomerville and Cambridge Street in Cambridge.
Ridership is highly distributed across stops inEverett, which lacks a rapid transit station to act
as a central boarding hub.
1 MBTA Daily Bus Ridership, Passenger-weighted crowding by route andhour for the week of September 7, 2020.

Ridership across all MBTA bus routes dropped
dramatically with the onset of the COVID-19
pandemic. Systemwide ridership saw a modest
increase at the end of 2020, hovering between
39% and 42% of pre-pandemic ridership levels,
while routes in the study area, Routes 104,
109, 111, 116, and 117, recovered between
56% and 60% of bus riders. This difference iseven more apparent when excluding Key Routeridership from systemwide totals – on average,
routes serving the study area have recovered
almost 20% more riders than routes that serve
other communities in the region. These starkdifferences in ridership patterns can be attributed
to a high concentration of transit-dependent
populations, and particularly bus-dependent
individuals, due to poor rail transit accessin Everett and Chelsea, as well as a highconcentration of workers who work jobs thatcannot be done from home and require them tocontinue commuting.

Travel Flows
Within the Inner Core2, most trips from Everett
and Chelsea are local. Approximately 44% of
trips, including both auto and transit, begin
and end in Chelsea or Everett; 27% of trips
from Everett and Chelsea end in Revere, East
Boston, or Malden; and the remaining trips end
in regional activity hubs like downtown Boston(4%), Logan Airport (2%), and Back Bay (1.5%).
When looking only at transit trips from Everett
and Chelsea, downtown Boston emerges as
the top destination for riders. 24% of transit
trips from Everett and Chelsea end in downtown
Boston and 23% begin and end in Everett andChelsea. Other top transit destinations are Back
Bay (5%) and the Longwood Medical Area (LMA)(4%).
Notably, Kendall Square is not shown as a top
current destination for Everett and Chelsea
transit riders. This is likely to be less of an issueof demand and more of an issue of access.
It is currently difficult to access the many job
opportunities in Kendall Square via transit (or by
driving). It takes over an hour and two transfers
to travel between most locations in Chelsea
and Everett and Kendall Square. The Silver Line
Extension process therefore looked more atlatent demand for this connection rather thanhistorical demand.
2 The Boston Area Inner Core Communities include Arlington, Belmont,
Boston, Cambridge, Chelsea, Everett, Lynn, Malden, Medford,
Melrose, Milton, Needham, Newton, Quincy, Revere, Saugus,
Somerville, Waltham, Watertown, and Winthrop.

MBTA Silver Line Extension Project Final Report

11

Existing Conditions
Figure 4 | Ratio of Weekday Off-Peak to Peak Bus Boardings

Existing Conditions

Transit Access, Travel Time, and Job AccessTraveling within and between communities in the study area by transit is challenging. Transit trips
between major study area locations can take 30, 45, or 60 minutes or longer and often require
one or more transfers. As shown in Figure 5, buses are delayed by congestion on most primarycorridors in the study area. Everett residents access the lowest number of jobs within a “typical”
commute time (45 minutes) relative to neighboring municipalities, in part due to the city’s lack ofaccess to high quality, high-capacity transit. Transit travel time access is illustrated for the following
transit centers in Figure 6 through Figure 9.
Figure 5 | Daily Passenger Minutes in Delay

12

MBTA Silver Line Extension Project Final Report

13

Existing Conditions

14

Existing Conditions

Figure 6 | Transit Access to Glendale Square

Figure 7 | Transit Access to Bellingham Square

Figure 8 | Transit Access to Everett Square

Figure 9 | Transit Access to Sullivan Square

Glendale Square has limited direct transit
access, with direct travel only available to theOrange Line at Malden Center and Sullivan. From
the Square, riders can travel along Broadway inEverett and Ferry Street in Malden without a needto transfer. A single transfer is required to accessthe rest of Everett as well as much of Chelsea.
Almost all of Somerville, as well as job centersin downtown Boston and Kendall and Central
Squares, are one transfer from Everett Square.
Downtown Boston and much of Somerville areaccessible within 45 minutes, while the rest of thecity and all of Cambridge take up to 60 minutes
to reach. Travel to the eastern part of Chelsea,
along with most of East Boston and Cambridge,
requires multiple transfers.

Bellingham Square has direct (one-seat ride)
travel available to the Orange and Blue Lines,
as well as to Everett Square, East Boston, anddowntown Boston. Transit riders beginning theirtrip at Bellingham Square have modest access tothe surrounding area. From Bellingham Square,riders can travel across Chelsea without the needto transfer. With a single transfer, almost all ofEverett, Malden, and Revere can be accessed.
Job centers in Cambridge’s Kendall Squareand Central Square are also one transfer away(although requiring a trip through downtown
Boston), along with downtown Boston and the
Seaport. Travel to Cambridge and Somerville,such as the Union Square area, requires multiple
transfers from Bellingham Square. Central
Square, Kendall Square, and most of Boston
typically take 45 minutes to reach, creating
challenges with job access to those employment
hubs. Transit rides of 60 minutes or longer are
required to reach some destinations in Medford,
Cambridge, and Somerville.

Everett Square has direct travel available to
the Orange and Blue Lines, as well as much ofChelsea and East Boston’s Day Square. Transit
riders beginning their trip at Everett Square havemodest access to the surrounding area. From
Everett Square, riders can travel across most ofEverett without a need to transfer. One-seat rides
to Malden Center, south Revere, and Day Square
are also available. A single transfer grants accessto most of Somerville, as well as job centers in
downtown Boston, and Cambridge’s Kendall andCentral Squares (albeit requiring a trip throughdowntown Boston). Travel to South Boston andmuch of Cambridge requires multiple transfersfrom Everett Square. Travel times from Everett
Square increase dramatically outside the peak
hours. Trips across the study area are moderate
to long and, compared to the AM peak, transit
riders from Everett Square headed to Boston
need 15 extra minutes to reach East Boston anddowntown Boston during midday, outside ofOrange Line stops.

Sullivan Square has short travel times tovarious destinations, with direct travel possible
throughout Somerville, Boston, Cambridge,
Everett, Malden, and Medford thanks to theOrange Line station and bus hub. From thestation, riders can directly travel across all of east
Somerville and to much of Everett, Cambridge,
and Boston within one transfer. Multiple transfers
are required only to reach the edges of Chelsea,
East Boston, and the South Boston Seaport.
Travel times from Sullivan Square to major
destinations in the study area vary by location
and by time of day, but access to high quality,
high-capacity transit dramatically increases
access within 30 minutes when compared to theother centers in the study area.

MBTA Silver Line Extension Project Final Report

15

Existing Conditions

Silver Line 3
The SL3 offers critical connections to residentsof the study area, particularly for people
traveling from Chelsea to downtown Boston
and to Boston Logan International Airport, oneof the region’s largest employers and majortransportation activity centers, sitting in the top
10 busiest airports on the East Coast.1
The SL3 provides service between 5:00
AM and 12:55 AM on weekdays, between
5:30 AM and 12:55 AM on Saturdays, andbetween 6:30 AM and 12:55 AM on Sundays.
Service frequency ranges between every 10
minutes during weekday peak hours andevery 12 minutes the rest of the weekday andon weekends. A one-way, end-to-end trip
between Chelsea Station and South Station
takes about 30 minutes on average.
In Winter 2020, the SL3 had an average
daily weekday ridership of 7,173, placing it
alongside the top highest ridership bus routes
in the MBTA system. During the height of thepandemic, the SL3 fared better than the MBTA
bus system as a whole, with 46% ridership
recovery as of Fall of 2021. The South Station,
Courthouse, Bellingham Square, and Airport
stations have the highest boardings of the SL3
on average.
The MBTA currently operates all Silver Lineroutes with a dedicated fleet of diesel-electricand battery-electric, articulated buses (BEBs)
for use on the Silver Line routes. The MBTA
is procuring enhanced electric hybrid (EEHs)
buses to replace aging Silver Line buses. The
new, 45-vehicle fleet is anticipated to be fully
operating in 2024.
There are a few infrastructure and operational
constraints within the existing SL3 alignment.
These are organized by the extremity of theconstraint. NOTE: None of these constraints
are addressed by the current SLXAA effort,
as other efforts are underway or have been
1 https://www.worldatlas.com/places/the-10-busiest-airports-in-theunited-states.html#h_9366558188651676392046068 (last accessed
February 28, 2023).

16

Existing Conditions

completed to help these constraints and theirimpacts on SL3 service.

bridge lifts to the public, so that travelers canplan accordingly.

Chelsea Street Bridge Openings: The bridge,
which is regulated by the United States Coast
Guard, opens and closes as requested byany maritime users, and as such opens as
many as ten times per day to allow passage
of ships carrying petroleum products to
upstream tank farms. Federal regulations givepriority to marine traffic at all times of day, andtherefore require the bridge to be opened on
demand, making transit time over the bridge
less predictable. The Chelsea Street Bridge
rises to the full extent at 175’ designed toaccommodate high tides and larger vessels
in the future. As a result, the Bridge lifts
last between 12 to 30 minutes on average,
meaning that a typical 30 minute trip between
South Station and Chelsea could be doubled
in travel time to 60 minutes due to a bridge lift
event, which may be longer if there are multiple
lifts back-to-back causing significant backups
on all approaches for all vehicles.

The City of Boston has proposed routing SL3
service through Day Square in East Boston andimplementing bus lanes on Chelsea Street fromDay Square to the Chelsea Creek bridge. If
implemented, these bus lanes would potentiallyreduce delays on the SL3 due to bridge lifts by
allowing SL3 buses to bypass queuing traffic
on Chelsea Street.2

In 2019 MassDOT submitted a request to theUnited States Coast Guard to allow the bridge
to open to 139 feet above mean high waterinstead of the full open position of 175 feet
unless a full bridge opening is requested. In
March 2020 the United States Coast Guard
granted this request by publishing a final rulein the Federal Register. By reducing the heightof the bridge lift, the total time the bridge islifted is reduced, therefore reducing travel
time impacts on SL3 service. MassDOT also
implemented both an advanced notification
system to alert users of future lifts and willsoon operate new equipment to better inform
users real time when a bridge lift is underway(variable message boards and beacon lights
at the top of the bridge). Finally, MassDOT has
made significant operational enhancements
to improve the reliability of the bridge and thecommunications to stakeholders.

Alford Street Bridge Openings: The Alford
Street Drawbridge provides an uninterrupted
connection between Everett and Charlestown
during most of the day. It is closed for thepassage of vessel traffic during the morning
peak hours and between 5 p.m. and 6 p.m.
daily and would minimally impact Silver Line
operations across the corridor.
Ted Williams Tunnel Congestion: When
traveling between Silver Line Way and the
Airport, SL3 buses use the regular travel lanes
through the Ted Williams Tunnel. Congestionin the tunnel can cause substantial travel timedelays, and although they are largely correlated
to the morning and afternoon rush hours they
can happen at any time when there is a backup
in traffic in the tunnel.
Seaport Circulation: When traveling from the
Ted Williams Tunnel to Silver Line Way, SL3
buses currently make a “loop” in the Seaportusing Haul Road, in the outbound direction,
or Congress Street, in the inbound direction.
Both routes are circuitous, add to travel times,
and increase the potential for delays because
buses are in general purpose travel lanes
when making these loops. SL3 buses also
experience delays at the D Street signal wherebuses are coming from the Silver Line Transit
Tunnel, crossing traffic at D Street, and need
to wait for a green light signal to proceed. The
2 https://www.bostonplans.org/planning/planning-initiatives/plan-eastboston

Bus Network Redesign project has proposed amodification to the SL1 and SL3 routes in the
Seaport to reduce travel time and delay. Under
the proposal, Silver Line buses would turn onto
D Street at the intersection of Silver Line Way
and D Street.

Pedestrian and Bicycle Conditions
The study area has a burgeoning but disparate
local and regional bicycle network, withapproximately 40 miles of on-street bikefacilities. Protected bike lanes account for
14% of the on-street bike network and bikelanes account for 60%. In addition to on-street
infrastructure, there are more than 30 miles ofoff-street multi-use trails within the study area.
There remains significant room to improveconditions for people biking in the study area.
While most neighborhoods have dense street
grids, which often indicate good walkability
and bikeability, some lack the dedicatedinfrastructure needed to enable people to feelsafe while biking amidst other vehicular traffic.
In some of these neighborhoods, expanding
the bike network may only require filling insmall network gaps around transit stations,while in others, more substantial efforts may beneeded to safely connect people biking fromsurrounding neighborhoods.
In general, sidewalk and pedestrian
infrastructure is safe and accessible acrossresidential neighborhoods and business
districts in the study area, where there is ahigher density of existing and potential riders
within walking distance to transit. Pedestrian
mobility is significantly more challenging in theindustrial portions of the study area, such as
Lower Broadway in Everett and Brickbottom
in Somerville. Besides being physically isolatedby railroads, arterial roads, and high truck andtrain volumes, the urban fabric or these areas is
not at this time conducive of pedestrian activity.

MassDOT has also maintained a Twitter
account @LogantoChelsea since 2016 thatprovides advanced and real time information on

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Existing Conditions

While neighborhoods themselves are very
walkable, traveling between them can behindered by the presence of busy arterials
and highways. The Newburyport/Rockportline and Route 16 in Chelsea and Everett,
McGrath Highway and the many rail lines in
East Somerville and East Cambridge, andRutherford Avenue in Boston make it difficult(and at times impossible) for pedestrians totravel comfortably between neighborhoods.

Traffic Conditions
The study area is comprised of some of
the largest and busiest communities in the
Commonwealth. Major roadways included in
the study network include Route 16 and Route28/McGrath Highway, Rutherford Avenue,
Broadway, and the dense street network

Existing Conditionsof East Cambridge between Lechmere andKendall. Some of the region’s most complex
traffic circles are part of the network: Sweetser
Circle, Santilli Circle, and Sullivan Square.
Major bridge structures that serve as points ofconstraint include the Alford Street Bridge, theGilmore Bridge, and the Charles River Dam
Bridge. Due to the vast nature of the study area
the Silver Line Extension focused on identifying
capacity constrained roadway corridors withnarrow rights-of-way where converting a travelor parking lane to a dedicated transit lane
could have implications on overall traffic; majorintersections with critical congestion levels that
could delay transit vehicles; and locations or
corridors with documented safety concerns.
Some of these roadways and intersections arehighlighted below.

Washington Street from Franklin Street to McGrath Highway is a High Bicycle and Pedestrian
Crash Cluster.
•

Rutherford Avenue (Route 99) (Boston) is generally two 11-foot-wide travel lanes in eachdirection, separated by a raised median and with turn lanes at key intersections Parking is
prohibited. Rutherford Avenue is currently under design for a major reconstruction of thecorridor.

•South of Chelsea Street, Rutherford Avenue continues as North Washington Street (Boston).
Between Causeway Street and New Chardon Street, North Washington Street provides two
10-foot to 11-foot travel lanes in each direction. A northbound on-street bicycle lane andsouthbound bus/bike lane are also provided in this segment. Parking is generally permitted
on the northbound side of the roadway. This corridor from Causeway Street to New Chardon
Street is a High Bicycle Crash Cluster.

•Charles River Dam Road (Route 28) (DCR) is generally two 10-foot travel lanes and an onstreet bicycle lane in each direction. Flexposts provide separation between travel and bicycle
lanes and parking is prohibited. The Edwin H. Land Boulevard intersection is a High Crash
Location, the corridor is a High Bicycle Crash Cluster from the Museum of Science to Edward
H. Land Boulevard, and a High Pedestrian Crash Cluster in the vicinity of Lechmere Square.

•First Street (Cambridge) is generally one 12-foot-wide travel lane and one 5 foot wide onstreet bicycle lane in each direction. Parking is generally permitted on the southbound side of
the roadway. Between Rogers Street and Binney Street, parking is prohibited to accommodatea turn lane. The First Street corridor from Cambridge Street to Otis Street is within a High
Pedestrian Crash Cluster.

•Third Street (Cambridge) is generally one 11- to 12-foot-wide travel lane in each direction,although lanes narrow to 10 feet at some intersections to provide an additional turn lane.
Parking is permitted along one or both sides along portions of the roadway. 5-foot wide
on-street bicycle lanes are provided on Third Street south of Binney Street. The Spring Street
intersection is a High Crash Location, and the Third Street corridor from Monsignor O’Brien
Highway to Otis Street is a High Pedestrian Crash Cluster.

Select Roadway Corridors and Traffic Circles:••

Broadway (Route 99) (Everett) is generally one 10-foot travel lane in each direction separated
by a double yellow center line. The bike and parking lanes operate as peak-direction bus/bikelanes along a portion of the corridor. The Broadway corridor from Second Street to High Street
is a High Pedestrian Crash Cluster.

•

Revere Beach Parkway (Route 16) (MassDOT) is generally three 12-foot travel lanes in eachdirection separated by a raised median. Parking is prohibited, and no shoulders are present. As
noted above, the Second Street intersection is a High Crash Location.

•

Sweetser Circle (MassDOT) is an approximately 450-foot outside diameter rotary connecting
Revere Beach Parkway with Broadway and Main Street. Revere Beach Parkway passes
beneath Sweetser Circle and is connected via ramps. Sweetser Circle was recently restriped tofunction as a modern roundabout and provides two circulating lanes and a bus lane.

•

Broadway (Route 99) (Everett) south of Sweetser Circle, Broadway generally provides
two 12-foot travel lanes and a bike lane in each direction, with a raised median. Parking is
prohibited. The Beacham Street intersection is a High Crash Location. Broadway continues
south into Boston as Alford Street, crossing the Mystic River via a drawbridge. South of the
drawbridge, Alford Street is connected to the Sullivan Square rotary via diamond interchange
type ramps.

•

•

18

Second Street (Everett) is generally one lane in each direction with single lane widths of 12
feet. The total roadway is 32 feet wide. The Revere Beach Parkway intersection is a High Crash
Location, and the Second Street corridor from Revere Street to Broadway is a High Pedestrian
Crash Cluster.

McGrath Highway (Route 28) (MassDOT) in Somerville is generally three 12-foot-wide
travel lanes in each direction, with turn lanes at signalized intersections. Parking is prohibited.
McGrath Highway continues into Cambridge as Monsignor O’Brien Highway where travel
lanes are 11-foot wide. This section is located within a High Pedestrian Crash Cluster. McGrath
Highway is currently under design for a major reconstruction of the corridor.

The full description of roadway corridors is included in Appendix B.
Key intersections included locations where potential lane reconfigurations would have the greatest
impact on traffic operations based on existing traffic operations, constraints on available width orright-of-way, or unusual complexity due to adjacent land uses, interactions of multiple modes oftravel, crash experience, planned projects, or other factors. Key Intersections in the study area
include:•Revere Beach Parkway (Route 16) at Second Street (Everett)•Broadway (Route 99) at Beacham Street (Everett)•Revere Beach Parkway (Route 16) at Santilli Circle (Everett)•Fellsway/McGrath Highway (Route 28) at Mystic Avenue (Route 38) (Somerville)•

Monsignor O’Brien Highway (Route 28) at Third Street (Cambridge)

A full description of these key intersections is included in Appendix B.
The analysis showed that even with the proposed Silver Line service in place, with signal andinfrastructure upgrades traffic flow would operate at generally acceptable conditions, in relation tovolume-to-capacity and/or level of service, at these critical locations. This also suggests that other,less challenging locations along the corridors would also be able to accommodate the project.

Cambridge Street (Boston) and Washington Street (Somerville) is generally one 11-footwide travel lane and a buffered bicycle lane in each direction. Parking is generally permitted.
MBTA Silver Line Extension Project Final Report

19

Existing Conditions

Environmental and Public Health
Conditions
Overall, the study area is primarily urbanizedwith scattered areas of open space. None of
the environmental conditions within the study
area constrain the development of alternativeroute alignments.
Throughout the study area, road traffic, aviation
activity, and nearby rail lines contribute tohigher noise levels than much of Boston’s Inner
Core. Traffic noise is a concern for residences
adjacent to highways or busy state routes.
Another major source of noise in the study
area is created from the aviation traffic travelingin and out of Boston Logan International
Airport. The areas with highest rail noise levelsin the study area appear to be where the
MBTA’s Green Line, Orange Line, and multiple
Commuter Rail lines converge in the East
Somerville/Inner Belt area heading towards
North Station.

20

In Chelsea, one of the top five environmental
concerns identified included outdoor air
quality. In Boston, the top environmental
health concerns include outdoor noise and air
pollution from vehicles and dangerous traffic.
Also worth noting is that transportation access,including Route 111 and the Silver Line, wasnoted as a community strength.
Across all communities in the study area,
access to health care and services was
identified as a primary concern. Most
communities in the study area, including
Chelsea, Everett, and Malden, noted access tohealthy and affordable food was a public healthconcern.

MBTA Silver Line Extension Project Final Report21

Alternatives Analysis

Alternatives Analysis

Alternatives Analysis

Table 3 | Preliminary Concepts

The LPA was identified through a three-stepevaluation process, starting with a high-levelassessment of several ideas, and with eachsubsequent step applying a more robust andquantitative analysis:

Step 1. Screening against Project Purpose

Section

Step 2. Tier 1 Evaluation (performed at ageographic level)

1

Step 3. Tier 2 Evaluation (performed at an
end-to-end route level)
This three-step evaluation process is illustrated
in Figure 10 below.

Figure 10 | Silver Line Extension Alternatives Analysis Evaluation Process

Concept
Concept Name
Code
1A*

Rail Right-of-way to 2nd to
Route 16

Chelsea Station – Rail Right-of-way – 2nd Street – Route 16 –Sweetser Circle

1

1B

Spruce Street / 2nd Street

Chelsea Station – Everett Avenue – Spruce Street

1

1C

Rail Right-of-way

Rail Right-of-way – Sweetser Circle

1

1D

2nd Street / Spring Street

Spring Street – Chelsea Street – Broadway – Sweetser Circle

1

1E

Everett Avenue / Route 16

Chelsea Station – Everett Avenue – Route 16 – Sweetser Circle

1F

Continue on 2nd Option

Chelsea Station – Rail Right-of-way – 2nd Street – Broadway –Sweetser Circle

1

1G

Upper Broadway

Glendale Square – Broadway – Sweetser Circle

22A*

Lower Broadway

Sweetser Circle – Lower Broadway – Sullivan Square

2B

Rail Right-of-way to Lower
Broadway

Sweetser Circle – Rail Right-of-way – Lower Broadway – Sullivan
Square2C

Route 16

Sweetser Circle – Revere Beach Parkway – Wellington

2D

Rail Right-of-way to Rail
BridgeRail Right-of-way – New Bridge – New Alignment – Sullivan Square

3A*

Inner Belt

Sullivan Square – Washington – Inner Belt Road – McGrath – Lechmere – First Street – Binney Street – Third Street – Kendall Square

3B

Fellsway / McGrath

Wellington – Fellsway – McGrath – Lechmere – First Street – Binney
Street – Third Street – Kendall Square

3C

Washington / McGrath

Sullivan Square – Washington – East Somerville – McGrath – Lechmere – First Street – Binney Street – Third Street – Kendall Square

3D

Rutherford / Gilmore

Sullivan Square – Rutherford Avenue – Gilmore Bridge – Charles
River Dam Road – Lechmere – First Street – Binney Street – Third
Street – Kendall Square

3E

Grand Junction Option(From McGrath) – Grand Junction Line – Binney Street – Kendall
Square3FLand Blvd Option(From Lechmere) – Charles River Dam Road – Land Boulevard –Binney Street – Third Street – Kendall Square

3G

Assembly Option

Wellington – Grand Union – Sullivan – Washington (continues alignment of 3A)

4A*

Rutherford to North Station

Sullivan Square – Rutherford Avenue – Washington Street – North
Station4B

Lechmere to North Station

Lechmere – Charles River Dam Road – Marth Street – North Station – Nashua Street

4C

Connection to Haymarket
Option (from the east)(From Washington Street Bridge) – Washington Street – Haymarket

Connection to Haymarket(from the west)(From Washington Street or North Station) – Merrimac Street –Haymarket

1

2
2
2
3
3
3
3
3
3
3
4
4

The study area was organized into four
sections, which are listed below:

22•

Section 1: Chelsea Station or Glendale
Square to Sweetser Circle in Everett•

Section 2: Sweetser Circle to the Orange
Line•

Section 3: Orange Line to Kendall Square•

Section 4: Orange Line to Downtown
BostonMunicipal stakeholders and the public were
engaged for each step of the evaluation
process. The first round of public engagement
helped to create the universe of 22 potential
concepts that were ultimately considered. This
universe of ideas is shown in Table 3.

Description

44* Preferred Alignment from LMRWG Study

MBTA Silver Line Extension Project Final Report

23

Alternatives Analysis

Screening Against Project Purpose
The screening phase of the evaluationconsidered each of the preliminary concepts
against the minimum requirements of the
project’s purpose. Screening criteria represent
this set of minimum requirements and werebased on existing or readily available data andmay reflect regulatory or policy imperatives.
These screening criteria, listed below, alignspecifically with the project purpose.
1.	 Does the concept either create new or
improve existing transit connections
between Chelsea and Everett or improvetransit services within Chelsea or Everett?
2.	 Does the concept continue on from Everett
to the Orange Line, Somerville, Cambridge,
and/or Boston?

the screening phase: concepts 2D, 3E, and
3G. The remaining 19 concepts were advanced
for Tier 1 Evaluation. The results of thescreening process are further documented inAppendix B: Silver Line Extension Alternatives
Analysis Screening.

Tier 1 Evaluation
The Tier 1 Evaluation identified the best
performing alignments within specificcommunities. For example, Tier 1 exploredmany ways to connect Chelsea Station andEverett Square, different ways to connect
Everett Square with the Orange Line, etc. It
was structured to identify which concepts best
achieve the project goals and objectives bysection. The following descriptions and maps
describe the concepts considered in the Tier 1
Evaluation.

3.	 Does the concept serve the identified
needs of transit-critical populations?
4.	 Does the concept avoid displacing thedwellings of any transit-critical populations?
5.	 Does the concept provide a relatively directline of travel1?
6.	 Is this concept compatible with local plans
and/or priorities?
7.	 Is this concept feasible from an engineering
perspective?
8.	 Can the concept be permitted from anenvironmental perspective?
Preliminary concepts that met these screening
criteria were considered generally feasible
and relevant and were developed into project
concepts to be advanced into the Tier 1
Evaluation process. Any concept receiving a“no” response was considered infeasible and/or
nonresponsive to the project purpose, and was
dropped from further consideration, without
any design or evaluation.
The Internal and External Stakeholder Working
Groups reviewed the screening results thatwere then made available for public comment
during and after the April 2021 Public Meeting.
In total, three concepts were removed during
1 Defined as no more than double the length of a straight-line roadway
path of travel.

24

MBTA Silver Line Extension Project Final Report25

Alternatives Analysis
Figure 11 | Section 1: Chelsea Station or Glendale Square
to Sweetser Circle in Everett

Figure 12 | Section 2: Sweetser Circle to theOrange Line

Figure 13 | Section 3: Orange Line to Kendall Square

Figure 14 | Section 4: Orange Line to Downtown Boston

Section 1: Chelsea Station or Glendale Square
to Sweetser Circle in Everett

Section 2: Sweetser Circle to the Orange Line

Section 3: Orange Line to Kendall Square

Section 4: Orange Line to Downtown Boston

Section 2 had four concepts:

Section 4 concepts include:
Six concepts in Section 3 advanced to the Tier 1 Evaluation.
Concepts 3A to 3D share an alignment from First Street, at•Concept 4A began at Sullivan Square Station, operated on
Lechmere Station, to Kendall Station, along First Street, Binney
Rutherford Avenue, and then continued across the North
Street and Third Street.
Washington Street Bridge into Downtown Boston. It thenThere were seven concepts in Section 1:
•

•

•

•

Concept 1A began at Chelsea Station and operated along
the commuter rail right-of-way, Second Street, and Revere
Beach Parkway, until Sweetser Circle.

•

Concept 2A began at Sweetser Circle and operated
entirely along Broadway in Everett and Alford Street in
Boston to reach Sullivan Square Station.

•

Concept 2B began at Sweetser Circle, operated along
the commuter rail right-of-way to Horizon Way, and thenused Horizon Way to reach Broadway. It then continued on
Broadway in Everett and Alford Street in Boston to reach
Sullivan Square Station.

Concept 1B began at Chelsea Station and operated along
Everett Avenue, Spruce Street, Second Street, and Revere
Beach to reach Sweetser Circle.
Concept 1C began at Chelsea Station and then operated
entirely along the commuter rail right-of-way to Sweetser
Circle.
Concept 1D began at Chelsea Station and operated along
the commuter rail right-of-way, Second Street, and Spring
Street. It then continued on Chelsea Street to Everett
Square and ran on Broadway to reach Sweetser Circle.

•

Concept 1E began at Chelsea Station, continued along
Everett Avenue to Revere Beach Parkway, and thencontinued on Revere Beach Parkway to reach Sweetser
Circle.

•Concept 1F began at Chelsea Station, continued along thecommuter rail right-of-way to Second Street, continued
along Second Street to Broadway, and then continued on
Broadway to reach Sweetser Circle.

•

26

Alternatives Analysis

Concept 1G began near Glendale Square in Everett andcontinued entirely on Broadway to reach Sweetser Circle.

••

Concept 2C began at Sweetser Circle and operated on
the Santilli Connector to Santilli Circle, then the Route 16
Bridge. After crossing the Malden River, the alignment used
the Rivers Edge Drive ramps and station access roads toreach the Wellington Station busway.
Concept 2D began at Everett Square and operated along
Broadway, Ferry Street, and Centre Street to reach Malden
Center Station. (Not Pictured.)1

1 A connection to the Orange Line at Malden Center was introduced into
the analysis during the second round of public outreach (Fall 2021),
as the preliminary Tier 1 results were being presented to internal andexternal stakeholders. Support for a Malden Center connection was also
voiced through the second public survey and at the second online public
meeting.

••

Concept 3A began at Sullivan Square Station and operatedon Washington Street and Inner Belt Road. It then entereda new structure across the commuter rail and Green Line
Extension right-of-way to reach Morgan Avenue. It thencontinued on First Street to Lechmere Station.
Concept 3B began at Wellington Station, used the station
access roads and the Rivers Edge Drive ramps to reachRevere Beach Parkway, and operated through Wellington
Circle to Route 28. It then continued on Route 28 until First
Street, near Lechmere Station.

•

Concept 3C began at Sullivan Square Station and operates
on Washington Street to Route 28. It then followed the sameroute to Kendall as Concept 3B.

•

Concept 3D began at Sullivan Square Station and operated
on Rutherford Avenue to Austin Street/Gilmore Bridge. Aftercrossing the Gilmore Bridge, it then continued on Route 28 toFirst Street until Lechmere Station.

•

Concept 3F – From East followed the same alignment as
Concept 3D, but used Land Boulevard, instead of First Street,to run between Route 28 and Binney Street.

•

Concept 3F – From West followed the same alignment as
Concept 3C, but used Land Boulevard, instead of First
Street, to run between Route 28 and Binney Street.

turned onto Causeway Street and terminated near North
Station.
•Concept 4B began near Lechmere Station, operated on
Route 28 across the Charles River, and then terminatednear North Station via a loop on Martha Road and Nashua
Street.

•Concept 4C began at Sullivan Square Station, operated on
Rutherford Avenue, and then continued across the North
Washington Street Bridge into Downtown Boston. It thencontinued on North Washington Street and terminatednear Haymarket Station.

•

Concept 4D began near Lechmere Station, operated on
Route 28 across the Charles River, passed North Station,and then used Merrimac Street to reach Haymarket
Station.

MBTA Silver Line Extension Project Final Report27

Alternatives Analysis

Alternatives Analysis

Tier 1 Evaluation Findings
Each of the concepts were evaluated against
the goals, objectives, and metrics shownin Table 4. Appendix C: Tier 1 Evaluation
Methodology Memo details the methodology
and findings from the Tier 1 Evaluation process.
Because the units of data varied by metric,
and each goal area contained several metrics,

Mobility and Accessresults were aggregated into a five-point scalefrom Low to High as outlined below.
The Tier 1 scoring was done on a section-bysection basis, comparing the different concepts
with one another within each section. Scoring
did not compare a concept in one section
against a concept in a different section.

Figure 15 | Tier 1 Five-Point Scale

There was a wide range of performancefor mobility and access, ranging from very
high to moderate and poor ratings. Overall,
concepts in Section 1 that served Chelsea
and Everett provided both mobility and accessbenefits, with those connecting Chelseawith Everett Square performing the highest.
Those in Section 2 serving Lower Broadway
provided better access benefits than the otherconcepts. Service along Washington Street
to Kendall in Section 3, and concepts serving
both Charlestown and Haymarket in Section
4, provided the most access and mobility
benefits.

EquityTable 4 | Goals and Tier 1 Metrics

Goal Area
Expand Mobility
and Access•Total trips beginning, ending, or passing through area served byconcept•

Number and quality of transfer opportunities•

Provides service within one or more of the Bus Network Redesign’s
identified High Priority Corridors

Advance Equity••

Improve Safety•

Number of affordable housing units within ½ mile of the concept
Proportion of transit critical population (people of color, low-income
households, zero vehicle households)
Existing or potential for accessible pedestrian path•

Existing or potential bicycle connections••

Ability to address known safety issues
Ability to remain outside known areas of climate change vulnerability
OR ability to construct alignment so that it would withstand climatechange vulnerability
Proportion of alignment that could support dedicated transit facilities(sketch analysis) – on entire alignment and alignment segments with
MBTA bus service

Support Climate
Change Resilienceand Sustainability
Advance Feasible
and Implementable
Solutions28

Tier 1 Metrics• Total employment (existing or projected) within ½ mile of the concept••

Extent of active planning efforts on identified corridors•

Extent of known community support•

Number and extent of known major cost items•

Number and extent of new connections between major activity centers

Almost all concepts performed well in relation
to equity, which is unsurprising because manyof the areas served by them are communities
with high concentrations of transit-critical
populations. There was variety between
sections: alignments in Chelsea and Everett
have higher proportions of transit-critical
populations served than alignments in otherparts of the study area, and so overall, theSection 1 concepts performed better in relation
to equity benefits. Of the sections, Section
3 showed the largest variation between
concepts. In particular, the percentage of the
population who are people of color withinwalking distance of the alignment varied greatly
between concepts, with the alignments routing
through Charlestown performing worse thanthe other concepts.

SafetyThe safety goal area also had wide variation
between concepts in each of the four sections.
One difference was in terms of connections
to the bicycle network. Alignments thatserve activity centers such as Everett Center,
concepts that serve Lower Broadway, andconcepts along Washington Street in Somervilleall interact and intersect with existing bicycle
facilities, and they generally performed well inthis metric.
In addition, there was some differentiation
between concepts in relation to addressing
known safety concerns. Most concepts
interface with locations with one or more safetyconcerns, but design adjustments associatedwith the Silver Line Extension investment are
anticipated to address them as part of the
project scope. Other concepts, like Concept
3B, which approached Wellington Stationfrom the west, faced more challenging safetyconcerns that would need to be addressed aspart of a larger effort.

Climate Resiliency
Climate change resiliency in the Tier 1
Evaluation was limited to looking at alignmentsthat interacted with locations that arevulnerable to flooding and a 21-inch sea levelrise.13 All Section 1 concepts were outside
areas of projected sea level rise. In Section 2,
the two concepts that crossed the Alford Street
bridge, which has approaches vulnerable toflooding and sea level rise, scored worse thanthe concept extending to Wellington.
Within Sections 3 and 4 there was little
differentiation between concepts, and all ofthem showed some level of vulnerability toflooding and sea level rise. Those concepts
that interfaced with Inner Belt and Brickbottom
areas – 3A, 3D, and 3F-From East – scoredworse than the others, and Concept 3C
Washington to McGrath performed better.
The entirety of Section 4 is highly vulnerable
to flooding and sea level rise, and thus allconcepts received Low scores.

Feasibility and Implementation
This goal area relied on preceding work doneby municipal partners to identify feasible
corridors that could serve current and future
markets. Within Section 1, concepts thatserved Everett Center via the Second Street
corridor were most compatible with previous
and ongoing plans. From a cost and easeof implementation perspective, Concept 1C,
which operated entirely along the commuter
rail right-of-way, was more challenging than
the alignments on Second Street between
the commuter rail right-of-way and north of
Route 16. The commuter rail right-of-way alsopresented a challenge in Section 2, specificallytying into Lower Broadway south of the Encore
Casino. Within Section 3, the major costelements required to construct a bridge overthe commuter rail and GLX tracks between
Inner Belt Road and First Street in Cambridge,
MBTA Silver Line Extension Project Final Report29

Alternatives Analysis

Alternatives Analysis

in the context of current construction plans,caused that concept to perform poorly. In
Section 4, the turning radii and roadway
right-of-way constraints in the vicinity of North
Station caused those alignments to perform
worse than the options that connected with theGreen and Orange Lines at Haymarket.

Tier 1 Evaluation Results
Table 5 | Tier 1 Concepts advanced to Tier 2 Evaluation
SectionNo.

Concepts
to Move
into Tier 2

Section 1

1D

1G

Section 2

2A

2C

Section 3

3C

3F-WestSection 4

4C

2D

In Section 1, Concepts 1D and 1G wereadvanced into the Tier 2 Evaluation. Concepts
1D and 1G scored high across the Safety,
Climate Resilience, and Feasibility and
Implementation goal areas. All their potential
station areas are accessible by pedestrians andthey both overlap with dedicated bike facilities.
Furthermore, both are compatible with previous
efforts that explored transit connecting Chelsea
and Everett and within Everett. Both align with
the Everett Transit Action Plan, and Concept
1G is also compatible with the Lower Mystic
Working Group study.
Concept 1D has the added benefit of providing
direct access to Everett Square and themany jobs in its vicinity. While job access islower for Concept 1G, since its surrounding
neighborhood is mostly residential, dedicatedtransit facilities along Broadway could benefit
several local MBTA routes that also operate on
the corridor.
In Section 2, Concepts 2A, 2C, and 2D were
forwarded into the Tier 2 Evaluation. Concept
2A, which connects to Sullivan Station, serves
the Lower Broadway corridor, which includes
major employers such as the Encore Casino
and the MBTA Everett Maintenance Facility.
Concept 2C serves retail plazas and offices
along Route 16 and at Wellington, which havefar fewer total jobs accessible within walking
distance of the alignment than the Lower
Broadway concepts.

30

Concepts 2A and 2C perform well in the Equity
goal area. Concept 2A serves a high proportionof zero-vehicle households, and Concept 2Cserves a high proportion of people of color andlow-income households. In terms of Climate
Resiliency, however, Concept 2A received a
Low score due to its alignment across the
Alford Street Bridge, which has approaches
that are highly vulnerable to flooding and sea
level rise.

Only one Section 4 concept was advanced
into the Tier 2 Evaluation, Concept 4C. This
concept operates mostly on roads that could
accommodate dedicated bus lanes in both
directions and do not appear to cross any
critical pinch-points. It outperformed the otherconcepts in this section in Mobility and Accessand Safety. As it extends into downtown

Boston to serve Haymarket, Concept 4C
provides access to more jobs than Concepts
4A and 4B. It also provides more transfer
opportunities for riders looking to travel farther.
Concept 4C also serves Sullivan Square andHaymarket, which have far more transfer
opportunities than Lechmere alone, in the caseof Concept 4A.

Figure 16 | All Tier 1 Concepts

With substantial reconfiguration, theroadways serving most of Concept 2A could
accommodate dedicated bus lanes in both
directions. Feasibility and Implementation forConcept 2C, which connects to Wellington,
could be more challenging because mostof the roads on the alignment likely cannot
accommodate dedicated bus lanes orplatform-style stations. Both concepts are also
relatively consistent and compatible with otherplanning efforts, including the Lower Mystic
Regional Working Group, Wellington Circle
Study, and Wellington Station Redesign.
Concept 2D performed well at connecting
existing and potential riders with desirable
destinations. The concept performs well in
relation to equity and climate change resiliency.
There are some concerns over the ability tocreate transit priority along the Ferry Street
corridor sufficient to provide travel time benefits
or reliability benefits.
In Section 3, Concepts 3C and 3F-FromWest were advanced into the Tier 2 Evaluation.
These two concepts performed better thantheir counterparts across several metrics. Theyboth serve a higher proportion of transit critical
populations and operate mostly on roads that
could accommodate dedicated bus lanes inboth directions and do not appear to cross
any critical pinch-points (short segments orintersections that could not be feasibly modified
as part of this project). They also provide a newtransit connection with high utility, including
improved connections between the Orange
Line and Kendall Square and a potential newconnection from the northern Orange Line andthe First Street corridor in Cambridge. Concept
3C provides access to a high concentration ofjobs near Union Square and Boynton Yards. It
also provides multiple transfer opportunities torapid transit and high-frequency bus routes.

MBTA Silver Line Extension Project Final Report31

Alternatives Analysis

Tier 2 Evaluation
The Tier 2 Evaluation connected the best
performing concepts from Tier 1 (seeTable 5 above) into end-to-end alternatives
and analyzed them for performance andeffectiveness on a capital and service basis.
There were seven Tier 2 alternatives in total.
Appendix E: Tier 2 Evaluation Methodology
Memo describes the assumptions that guided
the conceptual design and service planningwork that was done to define the Tier 2
alternatives.
The alternatives were organized into twogroups: a set of three alternatives that extend
the SL3 to the Orange Line, and a set of three

Alternatives Analysis

alternatives that provide a new service (called
the SL6 for evaluation purposes) extending
from Everett into Kendall Square in Cambridgeor into downtown Boston, as well as one
additional alternative that provides a newservice (also called the SL6 for evaluation
purposes) extending from Chelsea into Kendall
Square.

Figure 18 | Alternative 1:SL3 to Malden Center

SL3 Extension Alternatives: From
Chelsea to Everett and continuing on to
the Orange LineThe three SL3 Extension Alternatives areillustrated in Figure 17 below.

Figure 17 | SL3 Extension Alternatives
Figure 19 | Alternative 2:SL3 to Wellington

Each of the three SL3 Extension Alternatives connect Chelsea to theOrange Line via Everett Square. All three alternatives follow the same
path between the existing Chelsea busway and Everett Square. The
following describes what the three SL3 extension alternatives have incommon:•Extend the Chelsea busway within and along the southernedge of the commuter rail right-of-way (bi-directional transitway)
between the existing Chelsea station terminus and the Second
Street intersection.
•
Cross the Newburyport/Rockport commuter rail line tracks at
grade, and travel along Second Street to Spring Street via siderunning dedicated bus lanes (both directions).
•
Travel along Spring Street to Chelsea Street. There are two pieces
to this section:– Between 2nd Street and Revere Beach Parkway, the street
is assumed to be closed to general-purpose traffic, withdedicated bus lanes only. This condition would transition overtime -- in the short-term, buses would operate in generalpurpose traffic.
– Between Revere Beach Parkway and Chelsea Street, theSilver Line operates in general-purpose traffic.
•
Travel along Chelsea Street from Spring Street to Broadway. SL3
buses would utilize a westbound bus lane and operate in mixed
traffic eastbound.
At Broadway in Everett Square, the three SL3 Extension alternatives
differ as follows:
Alternative 1: SL3 to Malden Center connects with the Malden
Center Orange Line station. After reaching Everett Square, it would
operate on dedicated bus lanes along Upper Broadway and then in
mixed traffic on Ferry Street until reaching the Centre Street Busway
and Malden Center Station.

Figure 20 | Alternative 3:SL3 to Sullivan

Alternative 2: SL3 to Wellington would travel south along Broadway,
primarily in dedicated bus lanes until the approach to Sweetser Circle.
It would then continue in general-purpose lanes around Sweetser
Circle, the Santilli Connector, and Santilli Circle, and stay in mixed
traffic on Route 16 to Rivers Edge Drive, the approach to Wellington
Station.
Alternative 3: SL3 to Sullivan continues south on Broadway using
dedicated bus lanes. Silver Line vehicles would travel in the outerlanes of Sweetser Circle using bus-only lanes in both directions toreach Lower Broadway. Along Lower Broadway and Alford Street,buses would also largely operate in dedicated bus lanes. These bus
lanes continue over the Alford Street Bridge until just before Sullivan
Square Station.
For modeling purposes, the SL3 Extension frequencies we assumed
to be every 10 minutes on weekdays, except for night and late night
periods where frequencies would match the weekend frequency of
every 12 minutes.

32

MBTA Silver Line Extension Project Final Report33

Alternatives Analysis

Alternatives Analysis

New Silver Line Service (SL6) Extension Alternatives: From Chelsea and Everett to
Sullivan, continuing on to Kendall and/or Boston
The four SL6 Alternatives are illustrated in Figure 21 below.
Figure 21 | SL6 Alternatives

34

MBTA Silver Line Extension Project Final Report35

Alternatives Analysis

Alternatives Analysis

Three of the SL6 alternatives connect Everett with Kendall and one (Alternative 6) connects
Everett with downtown Boston.
All the alternatives that serve Kendall assumed a specific circulation between Kendall andLechmere. The SL6 would circulate westbound on Main Street, turn north onto Ames Street andeast on Broadway until the intersection with Third Street. Then the SL6 would follow the sameroute it traveled in the southbound direction. Upon further discussion, the City of Cambridge
suggested a different routing that uses Galileo Galilei Way, as opposed to Ames Steet. Further
study on Kendall Square circulation may be necessary before a preferred alignment is selected.

36

Figure 22 | Alternative 4: SL6 to Kendall via McGrath

Figure 23 | Alternative 5: SL6 to Kendall via Rutherford

Figure 24 | Alternative 6: SL6 to Boston via Rutherford

Figure 25 | Alternative 7: SL6 to Kendall from Chelsea

Alternative 4: SL6 to Kendall via McGrath begins in
Glendale Square in Everett and operates in side-runningbus lanes along Upper Broadway until it connects with
the SL3 Extension LPA in Everett Square and follows thatalignment until Sullivan Station. Silver Line vehicles would
exit Sullivan Station by turning onto Cambridge Street andcontinue along Washington Steet until McGrath Boulevard,
where the alignment would turn south and travel along
McGrath Boulevard until Lechmere Station for passengers
to connect to the Green Line. It was assumed that redesignof McGrath Boulevard would include dedicated bus lanes.
After stopping at Lechmere, buses head south on First
Street, then turn west onto Binney Street, and then backsouth along Third Street until Main Street and the Kendall
Red Line station.

Alternative 5: SL6 to Kendall via Rutherford follows
the same alignment as Alternative 4 from Glendale Squareto Sullivan Station. After stopping at Sullivan, Silver Line
vehicles would travel down a redesigned Rutherford
Avenue, which was assumed to have dedicated bus lanes,in Charlestown. Buses would then turn west to cross theGilmore Bridge and travel along McGrath Boulevard until
Lechmere Station. From Lechmere to Kendall, and back,
Alternative 5 would follow the same alignment as Alternative
4.

Alternative 6: SL6 to Boston via Rutherford is the
only SL6 alternative connecting to downtown Boston. This
alternative also began in Glendale Square and follows thesame alignment as Alternative 5 up until Rutherford Avenue,
where instead of turning on the Gilmore Bridge, it continues
down Rutherford and New Rutherford Avenues, crosses
the North Washington Street bridge, and travels along
Washington Street until reaching its southern terminus at
Haymarket Station.

Alternative 7: SL6 to Kendall from Chelsea provides
a one-seat ride from Chelsea through Everett to Kendall
Square. Instead of beginning at Glendale Square, this SL6
alternative begins at Eastern Avenue Station and travels
along the Chelsea busway to Chelsea Station, following
the same route as the existing SL3. Once the SL6 reaches
Chelsea Station, it would continue along the same alignment
as Alternative 3 to Sullivan Station. Between Sullivan Station
and Kendall Station, Alternative 7 would operate along an
identical alignment as Alternative 4, along Washington Street
and McGrath Boulevard and connecting with the Green Lineat Lechmere and the Red Line at Kendall.

SL6 Alternatives were modeled at higher frequencies than the SL3 Extension alternatives andmatch the level of service proposed for the MBTA’s Bus Network Redesign (BNRD) proposed
high-frequency network – every 5 minutes during weekday peak hours, every 8 minutes weekdays
midday, and every 10 minutes on weekends and weekday early mornings and nights.

MBTA Silver Line Extension Project Final Report37

Alternatives Analysis

Alternatives Analysis

As shown in Table 6, the Tier 2 metrics had astrong focus on equity, feasibility, and reliabilityof the proposed service.

Because the units of data varied by metric,
and each goal area contained several metrics,
results were summarized into a three-point
scale from “neutral” to “high” as follows:

Expand Mobility

Alternative 3:SL3 to Sullivan

Goal Area

SL3 to Wellington

Table 7 | Performance of SL3 Extension Alternatives
Alternative 2:

Quantification of performance is possible at thislevel of conceptual planning, but it is important
to note that Tier 2 Evaluation results are only
for relative comparison purposes between thealternatives. At this high level, values such as
travel times and costs lack precision that can
only be generated as more detailed planningand engineering is performed.

Results for SL3 Extension
Alternatives

CenterTier 2 Evaluation Results

Alternative 1:

The entirety of the Silver Line Extension
Alternatives Analyses overlapped with the
MBTA’s BNRD project. Given that the changes
to the MBTA bus network were still preliminary
at the time the Tier 2 Evaluation and all CTPS
modeling were being conducted, this study
used the Winter 2020 bus network for most of
the evaluation metrics. The Revised BNRD wasincorporated into metrics as much as possible
after it was released to the public. Coordination
occurred with the BNRD team throughout
the Tier 2 Evaluation process to ensure theassumptions and analyses were consistent.

SL3 to Malden

The Tier 2 Evaluation process differed from theTier 1 Evaluation in multiple respects. First, theanalysis used the CTPS Travel Demand Modelto assess ridership, changes in VMT, mode
split, and greenhouse gas reductions for eachalternative. The CTPS model used 2040 as theanalysis year, the Winter 2020 bus network as
its base, and a set of transportation and land
use investments as assumptions. The land use
assumptions started with those used for the
Lower Mystic River Working Group Study andadded projects in the development pipeline as
discussed in the Existing Conditions chapter.
For a full list of the transportation investments
included in the model, please see Appendix F:
Additional Transit Projects for Inclusion in the
CTPS No Build 2040 Model.

High

MediumAdvance Equity

MediumMediumHigh

Improve Safety

NeutralNeutralNeutralNeutralNeutralNeutralMediumMediumHigh

and Access

High

Support
Climate Change
Resilience andSustainability
Advance

Table 6 | Goals and Tier 2 Metrics

Goal Area

Tier 2 Metrics

Expand Mobility and AccessTotal Ridership (Daily)
Number of jobs accessible via 45-minute transit commute (Average by stop during AM
peak, midday)
Ratio of transit time to drive time (AM peak, midday)
Number of affordable housing units within ½ mile of a stop or station
TOD Propensity Score

Advance Equity

Percentage of commuters to jobs accessible by a 45-minute transit commute who rely
on transit
Average reduction in daily passenger minutes of delay on bus routes that overlap withthe alternative
Number of travel flows with more than 5,000 daily trips (weighted by low-income andminority trips) served by the alternative

Improve Safety

Ability for alternative to provide a connection to an existing pedestrian and bicycle facility
or to retain width for a new facility that is continuous, comfortable, and safe

Support Climate Change
Resilience and Sustainability

Change in transit mode split
Change in greenhouse gas emissions and VMTAdvance Feasible and
Implementable Solutions

Number of Silver Line buses needed to operate the alternative (Estimated fleet surplus
or deficit)
Extent to which investment could be included within other efforts upcoming or currently
underway
Extent that could operate within exclusive transit right-of-way
Planning-level cost estimate

Feasible andAll the proposed alternatives performed
positively across metrics, so it was decided
not to include low-performing categories
in the Tier 2 Evaluation scale. The use of a“high,” “medium,” and “neutral” rating systemthus allows for a comparative analysis of the
tradeoffs between each alternative’s ability
to best meet the project purpose and need.
Of note is that this scoring was done on acategory basis, comparing the different SL3and SL6 alternatives with one another withineach category. Scoring did not compare SL3
Extension alternatives against SL6 alternatives.

Implementable
Solutions

All three SL3 Extension alternatives havecomparable performances across several
evaluation metrics. All SL3 Extension
alternatives show that extending the SL3 to an
Orange Line station will significantly increase
the route’s ridership. The build alternatives
show ridership increases between 90% and150% when compared to the 2040 no-build
condition. Alternative 1 shows the highest
potential ridership, followed by Alternative 3.
All SL3 Extension alternatives also provide
tremendous access to jobs. Overall, people
riding the alternatives will have greater accessto jobs in the morning, which corresponds
to the bus network’s peak frequency period.
Despite connecting to a major bus transfer
hub like Malden Center, Alternative 1 connects
riders to the lowest number of jobs. The othertwo alternatives travel through and connect toareas of higher job density and intersect withmore transit routes, increasing the opportunities
for transfers.
The SL3 could be extended to any of thethree proposed Orange Line termini with theanticipated Silver Line fleet. Alternative 1, being
the longest alignment and having slightly lower
travel speeds than the other two alternatives,would require one additional vehicle to operate

38

MBTA Silver Line Extension Project Final Report

39

Alternatives Analysis

Each alternative presents a set of tradeoffs.
Alternative 1 to Malden Center performs wellin terms of ridership overall, and travel flows
serving transit-critical populations. Alternative
1 stands out among the others for its transitoriented development (TOD) readiness. Itsscore is reflective of high housing density andhigh percentage of transit-critical residents
along the corridor. Furthermore, it ranks highlyin pedestrian and bicycle access, due to adense street network with primarily residential
uses adjacent to the corridor. However,
Alternative 1 does not perform well when it
comes to transit priority along Ferry Street. Our
preliminary analysis showed that Ferry Street
is not wide enough to accommodate both bus
lanes and general-purpose lanes. The ongoing

40

Alternative 3 has a “high” performance inmost goal areas. It performs well on key
metrics like ridership, access to jobs, costeffectiveness, and, most importantly, transit
travel time reliability. Alternative 3’s alignment
has more capacity to accommodate dedicatedbus lanes than Alternatives 1 and 2, which
result in a greater transit travel time advantage
when compared to driving. Finally, Alternative
3 aligns well with upcoming efforts, or efforts
currently underway. A Silver Line Extension
along Lower Broadway connecting Everett to
Sullivan Station was a recommendation fromthe Lower Mystic Regional Working Group
report. Furthermore, this part of Everett is intransition; Lower Broadway is the location of
the recently constructed Encore Casino, andother development applications are underway.
Through this process, the City of Everett is
exploring the potential to require setbacks toallow more space for dedicated transit along
Lower Broadway, which would be beneficial for
Alternative 3.

reduced travel time delays, for all transit
services that can use the bus lanes.

Alternative 7:SL6 to Kendall
from Chelsea

Table 8 | Performance of SL6 Alternatives
Alternative 6:SL6 to Boston via
Rutherford

Travel time savings from dedicated bus lanes
and transit signal priority also extend to local
bus routes, which were assumed to be able touse all proposed infrastructure improvements,
except for the Chelsea busway extension.
Because we know that the local bus routes inour study area carry more people of color andpeople with low incomes, this has an equity
benefit.

Despite being the shortest route to an Orange
Line station and major bus transfer hub,Alternative 2 to Wellington has lower ridershipdemand than the other two SL3 Extension
alternatives. Almost half of Alternative 2
operates in mixed traffic. This alternative faces
right-of-way challenges along Sweetser Circle,
the Santilli Connector, and Santilli Circle. Westof Santilli Circle, the short operating distanceon Route 16 makes it unfeasible to installdedicated lanes in that segment. Finally, theramps connecting to Wellington Station are
not assumed to be widened to accommodate
additional bus lanes. This results in transit trip
times similar to driving times: when this stretchof roadway is congested, buses are caught
in the congestion too. However, because
it would not require construction beyond
Broadway, Alternative 2 is relatively costeffective.

Results for SL6 Alternatives
Alternative 5:SL6 to Kendall via
Rutherford

However, other metrics highlighted key
differences between the alternatives. By
design, all the SL3 Extension alternatives
also increase the extent of bus transit priority
along their respective corridors, especiallybetween Chelsea Station and Everett Square.
This increase results in improved travel time
reliability. Travel time reliability is highest for
Alternative 3, as it has the highest level oftransit priority, which improves travel times,
especially during peak congestion periods. Inturn, despite featuring dedicated bus lanes
between Chelsea Station and Sweetser
Circle, Alternative 2’s transit travel time is quite
comparable to the drive time. This is because
most of the traffic congestion for this alternative
is concentrated on Santilli Circle and Route 16,
segments where transit priority treatments were
not proposed due to operational and right-ofway limitations.

Ferry Street Reconstruction project will improvepedestrian safety by installing curb extensions
at intersections. Alternative 1 would carry thecost of removing the new curb extensions andreplacing them with queue jumps. Despite
the assumed transit signal priority and queue
jumps, the lack of dedicated transit facilities
has a detrimental effect on travel times andtravel time reliability.

Alternative 4:SL6 to Kendall via
McGrathbeyond the number of vehicles required for
Alternatives 2 and 3. Another metric withconsistent results across alternatives wastransit mode share, which did not vary greatly
across alternatives.

Alternatives Analysis

ExpandMobility andAccessHigh

High

MediumHigh

Advance
EquityHigh

MediumHigh

High

Improve
SafetyNeutralNeutralNeutralNeutralSupport
ClimateChangeResilienceand Sustainability

NeutralNeutralNeutralNeutralAdvance
Feasibleand Implementable
SolutionsHigh

MediumMedium

High

Goal
Area

Alternatives 4, 5, and 6 all connect Upper
Broadway in Everett with either Kendall Squareor downtown Boston in different ways. These
alternatives assume that the existing SL3alignment would be extended from Chelsea
Station to Everett Square along the Commuter
Rail right-of-way, Second Street, Spring
Street and Chelsea Street (as described in
Alternatives 1 through 3), allowing for a transfer
between the SL3 and the SL6. Alternative 7
aims to connect Chelsea and Kendall via a
one-seat ride.
As was the case for the SL3 Extension
alternatives, the Tier 2 evaluation revealed that
the SL6 alternatives have several things incommon:•All alternatives provide tremendous
access to jobs via transit and with little
difference between the peak hour andmidday.

•All alternatives increase the extent of bus
transit priority to between 75% and 90%of the alignment lengths. This lends itself
to competitive transit travel times and•

All the SL6 alternatives result in agreater transit mode share than the SL3
Extension alternatives, close to 3% higher
than the 2040 no-build scenario.

•

To operate any of the SL6 alternatives,
the MBTA would need to expand thesize of the Silver Line fleet by acquiring
new vehicles, which has downstream
impacts on where vehicles are stored andmaintained.

•

Finally, the SL6 alternatives all rely
on investments that are made byother parties. These investments inroadway and intersection redesign
and reconstruction would happen
outside of this process. The redesignof Sullivan Square, Rutherford Avenue,
Gilmore Bridge, and McGrath Highway
are necessary precursors to thesealternatives operating at their assumed
potential.

Among the key findings from the Tier 2
Evaluation is that ridership to Kendall is higher
than to Downtown Boston. While the project
team partially attributes this to an increasein future demand for this service as growthcontinues in the study area, the ridership model
results show that the ridership discrepancy ispartially due to Alternative 6 riders transferringto the Orange Line at Sullivan instead of staying
on the Silver Line to reach Downtown.
Each SL6 alternative also presents a set oftradeoffs. Alternative 4 to Kendall via McGrathconnects Everett residents with the Orange
Line at Sullivan, the Green Line at Lechmere,
and the Red Line at Kendall. It does very wellwith overall ridership. When combining the
projected SL3 and SL6 ridership, Alternative 4
has the most riders among all SL6 alternatives.
While it has the lowest extent of transit priority
among SL6 alternatives (75%), it still shows
great potential for travel time reductions foroverlapping MBTA services. Alternative 4runs through areas that are generally bike andpedestrian friendly and almost 90% of its stops
are accessible by bike.
Alternative 5 to Kendall via Rutherford
connects to an additional Orange Line station,

MBTA Silver Line Extension Project Final Report

41

Alternatives Analysis

Community College, in addition to Sullivan,
Lechmere, and Kendall. By nature of being
shorter in length, this alternative has a slightly
shorter travel time than Alternative 4, which
is further enhanced by a higher percentageof transit priority along its length (80%).
However, as is also the case with Alternative 4,
Alternative 5 is likely to experience delays whilecirculating around Kendall, particularly in theoutbound direction. A key distinction between
Alternatives 4 and 5 is the approach to Kendall
from Rutherford and the Gilmore Bridge. The
Gilmore Bridge currently experiences highlevels of traffic congestion. After consultation
with several stakeholders, the policy
assumption was made to model dedicated bus
lanes in each direction on the Gilmore Bridge
and a Silver Line station at Community College.
Pavement reconstruction and painting for bus
lanes are included in our cost estimates for thisalternative.
Alternative 6, from Everett to Haymarket via
Rutherford Avenue, is the only SL6 alternativethat connects Everett directly to Downtown
Boston. Alternative 6 performs well on anumber of metrics, including extent of transit
priority, access to jobs, access to affordable
housing units. Where Alternative 6 falls short ofits counterparts is ridership. Projected ridershipfor Alternative 6 is more than a third lower thanthat of other SL6 alternatives. This ridershipshortfall could be attributed to the many
competing services between Sullivan Station
and Downtown Boston. The CTPS ridershipmodel assumed the implementation of the
Red Line and the Orange Line Transformation
projects, which should result in 4-minute peakheadways for the Orange Line. Transit riders
along the Rutherford corridor may insteadchoose to ride the T101 bus route along asimilar alignment once BNRD is implemented.

Locally Preferred Alternative

although part of the estimate is riders diverted
from the SL3, with which it overlaps for muchof the Chelsea busway. This alternative also
shows promising travel time savings comparedto driving and it serves many of the travel
flows with high demand among transit-critical
populations. Like Alternative 4, it is estimatedthat operating Alternative 7 will require up to 13
new SL vehicles, the most for any alternative.

The Transition from Analysis
to Recommendations
The analysis results summarized above werediscussed with the External Working Group andwith the community through an online survey
and a public meeting. Overwhelming support
for transit priority investments were received
in general, and support favored extending theSilver Line to Sullivan as opposed to Wellington
or Malden Center. Support was also voiced forextending the Silver Line beyond the Orange
Line over time, and to both Kendall and
Downtown Boston.
While extending Silver Line service beyond
the Orange Line to either Kendall Square or
Downtown Boston provides potential ridershipbenefits, MassDOT concluded that further
study and the completion of ongoing planning
efforts by others is required to determine thefeasibility of implementing a Silver Line service
to either location. Moreover, this study foundthat procuring additional Silver Line vehicles,
and expanding vehicle maintenance andstorage capacity would be required. Therefore,
the primary recommendation from this study is
to extend the Silver Line to the Orange Line, as
is outlined in Chapter 5, the Locally Preferred
Alternative.

Locally Preferred Alternative
Alternative 3: SL3 to Sullivan is the LocallyPreferred Alternative (LPA) identified from theevaluation process. This LPA extends theexisting SL3 service from its current terminus at
Chelsea Station to the Sullivan Square Orange
Line Station. This section describes the transit

vehicle, alignment, station locations, andservice plan for the LPA. Design specifics
and the definition of additional elements ofthe project, including details related to station
locations, will be refined during subsequent
engineering and planning efforts.

Table 9 | LPA Key Statistics

SL3 to Sullivan: Key Statistics
Length: 6.36 Miles (roundtrip)

Assumed Average Dwell Time: 24 seconds1

Number of Stations: 7

Frequency: 10 minutes AM + PM PeakSpan of Service:

Major Transfer Locations:

4:20 AM-1:15 AM Weekday

Everett Square

4:55 AM-1:45 AM Saturday

Sullivan Station

5:50 AM-1:50 AM Sunday
Assumed Vehicle Load: 65 passengers2

Extent of Operation in Exclusive Transit Right-of-way:
80% (5.18 miles)

1 All-Door Boarding Pilot on the Silver Line (2017), OPMI Data Blog: https://massdottracker.com/datablog/?p=154. Assuming frontdoor boarding.
2 MBTA Service Delivery Policy, page 47: https://cdn.mbta.com/sites/default/files/2021-06/2021-service-delivery-policy.pdf

Alternative 7, the last of the SL6 alternatives,
was added to the Tier 2 Evaluation as partof the stakeholder engagement process.
The purpose of evaluating this alternative isto understand the impact and the demand
for a more direct connection from Chelsea
to Kendall. Despite being the longest andmost expensive route evaluated, Alternative
7 performs well on several fronts. It shows
the highest ridership among SL6 alternatives,

42

MBTA Silver Line Extension Project Final Report

43Locally Preferred Alternative
Figure 26 | LPA – Alternative 3: SL3 to Sullivan

Locally Preferred Alternative

LPA Alignment
The LPA would operate primarily on dedicatedbus-only lanes along an extended Chelsea
busway, Second Street, Broadway, Lower
Broadway, Alford Street, and across the
Alford Street Bridge to Sullivan Station. This
alternative would extend the existing SL3,
which operates between South Station and
Chelsea. The end-to-end service plan for this
LPA is from South Station to Sullivan Square.

From Chelsea Station to Everett Square
The LPA begins by extending the Chelsea
Silver Line busway by approximately 0.4 miles,
from its current terminus at Chelsea Station
to Second Street in Everett. This new busway
segment would run along the southern edge ofthe existing commuter rail tracks, mostly within
existing MBTA commuter rail right-of-way.
As shown in Appendix G: Busway Extension
Concept Drawing, much of the existing
commuter rail right-of- way appears sufficientto accommodate a 33-foot wide, bi-directional
busway. Some evidence of encroachment ofprivate business onto the commuter rail rightof-way has been identified, and some limited,partial right-of-way acquisitions are assumed.
Future survey to be collected as part of thedesign process would confirm these details. At
several points, the busway’s shoulder would
narrow for short segments, which is necessary
to avoid conflicts and relocation of existinghigh-voltage electricity poles running parallelto the corridor. The maintenance building andcomfort station that are currently adjacent to
Chelsea Station would also require relocation.
At Second Street, Silver Line vehicles would
turn northwest from the busway to Second
Street. A traffic signal would be installed at
this new intersection and connected to theadjacent railway crossing to allow four quadrant
gates to lower and Silver Line vehicles to wait
as trains travel through the intersection. In
addition, a new signal will be required at Third
Street to enable Silver Line vehicles to crossThird Street without conflict. These crossings
were assumed to be similar to those at existing
Chelsea busway intersections, such as thebusway at Everett Avenue, and the busway
at Spruce Street, where the railroad grade
crossings and busway intersection signals
are tied together to ensure safe and efficient
operations for all modes.
Reviewing the current speed, frequency, andlength of MBTA trains operating in this area,
as well as looking towards the future vision
for this railway line as identified in Rail Vision,
it is anticipated that delays caused by railroad
crossings to Silver Line service will be minimal.
Railroad crossing gates would lower for asimilar amount of time as a traffic signal ortransit stop, or approximately 30 seconds two
to six times per hour, and Silver Line vehicles
are able to operate parallel to trains except
at the Second Street grade crossing. Future
improvements to the Newburyport/Rockportcommuter rail line are anticipated to improvetrain frequency; however, the delays caused byadditional commuter trains to Silver Line service
still would not increase delays in a statisticallymeaningful way.
Today, Second Street has an approximate
curb-to-curb width of 32 feet, which precludes
the construction of dedicated bus lanes inboth directions. In the near-term, Silver Linebuses will operate in mixed traffic along thiscorridor. However, as redevelopment occurs
along Second Street in the future, right-of-way
widening to accommodate side-running bus
lanes between the busway and Spring Street
will greatly benefit Silver Line service.
Silver Line vehicles will then turn north onto
Spring Street. In the near term, buses will
operate in mixed traffic until Chelsea Street.
Long-term improvements to this corridor could
occur as part of the Revere Beach Parkway
redesign.1 This could lead to Spring Street
operating in two sections:
1.	 Between Second Street and Revere
Beach Parkway, the street could
potentially be made one-way for non-bus
traffic, or become a transitway, closed
to mixed traffic. Property access would
need to be addressed for the businesses
1 Route 16 in Chelsea and Everett was designated as a priority corridor
for multimodal infrastructure and traffic improvements. Short-,
medium-, and long-term strategies were identified to ameliorate safety,
congestion, infrastructure, operations, and environmental challenges(Route 16 Priority Corridor Study, CTPS, 2019).

44

MBTA Silver Line Extension Project Final Report45

Locally Preferred Alternative

located along the northern edge of theblock.
2.	 Between Revere Beach Parkway andChelsea Street, buses would remain inmixed traffic.

All intersection signals in this section assume
use of Transit Signal Priority (TSP) to improvethe efficiency and reliability of Silver Line andlocal buses.

SilverExtensions
Figure27Line| Proposed
TransitAnalysis
Configuration for the LPA -1

Locally Preferred Alternative Concept Map: From Chelsea Station to Everett Square

Three stops are assumed in this section:•

CR right-of-way and Second Street•

Second Street and Spring Street

New signal

SL3 Busway Extension

B

New signal with Transit
Signal Priority

Side-Running Bus Lanes

Existing signal, add
Transit Signal Priority

General-Purpose Lanes

Newbury/Rockport
Commuter Rail Line

Dedicated Busway

St

Chelsea Station

Stop/Station

d

•

n

to
os

Silver Line Service is expected
to operate in the following typesof transit priority:St

2nDiagrams showing the proposed transit
configuration in this section are shown in
Figures 27 and 28.

CR ROW @ 2nd St
St

tt
Evere

d
3r

To reach Everett Square, the Silver Line
vehicles would turn west onto Chelsea Street,where there would be a westbound dedicatedbus lane between Spring Street and Broadway.
Implementing this side-running bus laneassumes removing the existing westboundparking and bike lane, though details would
be confirmed during design. Buses in the
eastbound direction would operate in mixed
traffic.

Locally Preferred Alternative

Ave

d

2n

T
!

St

Chelsea Station

0

T
!

0.05

0.1

Miles

SilverExtensions
Analysis
Figure28Line| Proposed
Transit
Configuration for the LPA - 2

Locally Preferred Alternative Concept Map: From Chelsea Station to Everett Square

Spring St

Silver Line Service is expected
to operate in the following typesof transit priority:

Stop/Station
New signal

SL3 Busway Extension

New signal with Transit
Signal Priority

Side-Running Bus Lanes

Existing signal, add
Transit Signal Priority

General-Purpose Lanes

Newbury/Rockport
Commuter Rail Line

Dedicated Busway

2n

d

St

RevereBeach Pkwy

2nd St @ Spring St

en

rd

Ga

St

0

0.05

0.1

Miles

T
!

CR ROW @ 2nd St

46

T
!

MBTA Silver Line Extension Project Final Report47

Locally Preferred Alternative

Locally Preferred Alternative

Upon reaching Everett Square, Silver Linebuses would turn south onto Broadway . To
make this left turn more efficient for transit, theexisting right turn lane on Chelsea Street isassumed to become a “right turn only except
bus lane” and a bus turning phase will be
added to the signal . In its current configuration,
Broadway has peak-hour bus lanes andparking on both sides of the street . The LPA
would convert these peak-hour bus lanes tobecome all-day bus lanes, which would remove
on-street parking between Chelsea Street andSweetser Circle crossing Route 16 .

Circulation around Sweetser Circle will remain
as it is today. Buses operate in the outer lanesof the circle using the existing bus-only lanes inboth directions to reach Lower Broadway.

Silver Line Extensions Analysis

Figure30 Preferred| Proposed Alternative
Transit Configuration
for Map:
the LPA- 4 Everett Square to Sullivan Station
Locally
Concept
From0

All intersection signals in this section are
assumed to be equipped with TSP to improvethe efficiency and reliability of Silver Line andlocal buses.

0.05

0.1

Miles

Br
oa
dw
ay

From Everett Square to Sweetser Circle

T!

There is only one stop in this section:•

Broadway and Chelsea Street

T!

Diagrams showing the proposed transit
configuration in this section are shown in
Figures 29 and 30.

Sweetser
CircleRevere Beach Pkwy

Figure29Line| Proposed
TransitAnalysis
Configuration for the LPA -3
SilverExtensions

Locally Preferred Alternative Concept Map: From Chelsea Station to Everett Square

0

0.05

0.1

Co

Miles

ttag

Broadway @ Chelsea St
Ch

els

St

Bo

wd

T
!

t

oin

St

T
!

Br

Broadway @ Beacham St

SL3 Busway Extension
Side-Running Bus Lanes
General-Purpose Lanes
Dedicated Busway

Stop/Station

Br
oa
dw
ay

Silver Line Service is expected
to operate in the following typesof transit priority:

Spring St

St

Sc
h

d

oo

2n

lS

t

oa

dw

ay

ea

eS

New signal
New signal with Transit
Signal Priority
Existing signal, add
Transit Signal Priority
Newbury/Rockport
Commuter Rail Line

Silver Line Service is expected
to operate in the following typesof transit priority:
SL3 Busway Extension

Revere Bea

ch Pkwy

Side-Running Bus Lanes
General-Purpose Lanes
Dedicated Busway

48

Stop/Station
New signal
New signal with Transit
Signal Priority
Existing signal, add
Transit Signal Priority
Newbury/Rockport
Commuter Rail Line

MBTA Silver Line Extension Project Final Report49

Locally Preferred Alternative•

Broadway and Horizon Street•

Sullivan Station

Miles

dw
oa
Br

T
!

Ly
n

de

Broadway @ Horizon Way
M

ys

on

Broadway and Beacham Street

0.1

T
!

Three stops are assumed in this section:
•

0.05

ay

0

W
ay

All intersection signals in this section are
assumed to be TSP equipped to improve theefficiency and reliability of Silver Line and local
buses.

Locally Preferred Alternative Concept Map: From Everett Square to Sullivan Station

tic

St

St

Diagrams showing the proposed transit
configuration in this section are shown in
Figures 30 and 31.

De

xte

rS

t

Alf

ord

St

To continue to accommodate the busway
on Alford Street, bike lanes would be moved
off-street between Dexter Street and theAlford Street Bridge onto adjacent private
property . Once the LPA reaches the Alford
Street Bridge, the bidirectional bike lanes would
transition back into the street right-of-way via aseparated cycle track . This configuration would

Sullivan Square is currently undergoing aplanning and design effort that will dramaticallyreconfigure Sullivan Square station access andcirculation. This process is in its early stages
and the LPA does not assume specifics inrelation to roadways, parking, or location of bus
berths. However, it does assume a high levelof transit priority accessing and within Sullivan
Square, with bus passenger dropoff as close to
the Orange Line station as possible.

SilverLine Extensions Analysis
Figure 31 | Proposed Transit Configuration for the LPA - 5

riz

After emerging from Sweetser Circle,
southbound Silver Line buses would travelin mixed traffic a short distance along
Lower Broadway until the Bowdoin Street
intersection, after which they would merge
into a side-running southbound bus lane .
Between the Bowdoin Street and Langdon
Street intersections, one general-purpose lanein each direction would be removed and theremaining four general-purpose lanes would
transition to the southern side of Broadway toaccommodate a new bi-directional busway
on the northern side . This configuration, witha busway on the north and general-purpose
lanes on the south with bike lanes on bothsides, would continue until the Dexter Street
intersection, after which the available right-ofway narrows significantly .

continue across the bridge until the approachto Sullivan Station.

Ho

From Sweetser Circle to Sullivan Station

Locally Preferred Alternative

Silver Line Service is expected
to operate in the following typesof transit priority:
SL3 Busway Extension
Side-Running Bus Lanes

50

MBTA Silver Line Extension Project Final Report

Stop/Station
New signal
New signal with Transit
Signal Priority

General-Purpose Lanes

Existing signal, add
Transit Signal Priority

Dedicated Busway

Newbury/Rockport
Commuter Rail Line

MBTA Silver Line Extension Project Final Report

51

Locally Preferred Alternative

Locally Preferred Alternative

Service Characteristics

Silver Line Extensions Analysis

Figure 32Preferred| ProposedAlternative
Transit Configuration
the LPA- 6 Everett Square to Sullivan Station
Locally
ConceptforMap:
From

Side-Running Bus Lanes
General-Purpose Lanes
Dedicated Busway

0.1

rd
St

New signal with Transit
Signal Priority
Existing signal, add
Transit Signal Priority
Newbury/Rockport
Commuter Rail Line

Miles

tB
ridg

0.05

New signal

My

sti

Alfo

rd S

tree

0

Alf
o

SL3 Busway Extension

Stop/StationeSilver Line Service is expected
to operate in the following typesof transit priority:

Table 10 | SL3 Assumed Levels of Service

cR

ive

r

Weekday

Saturday

SundaySundaySpan of Service

4:20 – 1:15 AM

4:55 – 1:45 AM

5:50 – 1:50 AM

Time Period*

Frequency (minutes)

Frequency (minutes)

Frequency (minutes)

Early
Before 6:00 AM

10

12

12

AM
6:00 – 8:59 AM

10

12

12

Midday9:00 AM – 2:59 PM

10

12

12

PM
3:00 – 5:59 PM

10

12

12

Night
6:00 – 11:59 PM

12

12

12

Late
12:00 AM and later

12

12

12

* Based on CTPS-defined time periods

Assumed Vehicle Load:
65 passengers
Assumed Average Dwell Time:
24 seconds1
Major Transfer Locations:Everett Square, Sullivan Station

Sullivan SquareSpecific Circulation between
the Alford Street Bridge, andwithin Sullivan Square, will be refinedin concert with the Sullivan Square
Reconstruction Project led by theCity of Boston

I-93

T
!

•

Everett Square: On-street bus stops.
Transfer to bus routes serving the samestop or serving on-street stops across thestreet.

•Sullivan Station: Outdoor bus berths
adjacent to MBTA Orange Line station andparking lot. Transfer to buses in the same
designated area. Transfer to Orange Lineplatforms via escalator or elevator.

T!

1 All-Door Boarding Pilot on the Silver Line (2017), OPMI Data Blog:
https://massdottracker.com/datablog/?p=154. Assuming front-doorboarding.

52

MBTA Silver Line Extension Project Final Report

53

Locally Preferred Alternative.

Basis for the LPA
Table 11 highlights some of the key benefits that provide the basis for this LPA .
Table 11 | Metrics and LPA Findings

Goal

MetricLPA Findings
SL3 No Build: 12,400 riders

1: Expand
Mobility &Access1.1

Total Daily Riders

1: Expand
Mobility &Access1.2

Access to Jobs via 45-minute Transit AM Peak: 347,000 jobs
CommuteMidday: 344,000 jobs

1: Expand
Mobility &Access1.3

Ratio of transit time to drive travel
time (AM Peak, midday)

2: Advance
Equity2.2

Average reduction in daily passenger
minutes of delay on bus routes thatoverlap with the alternative

SL3 Build Alternative: 27,800 riders(+15,400 No-Build)

Estimated Transit Travel Time (oneway): 17 mins
Ratio of transit travel time to drive
travel time: 61% (mid-day)
2.9 minutes

Goal 5: Advance Feasible and Implementable Solutions
5: Advance
Feasible &Implementable
Solutions

12 vehicles
5.1

Number of Silver Line buses needed
to operate the alternative(Estimated fleet surplus: 6 vehicles)

5: Advance
Feasible &Implementable
Solutions

5.2

Extent of Silver Line that could
operate within exclusive transit
right-of-way

High (80%)

5: Advance
Feasible &Implementable
Solutions

5.4

Planning Level Cost Estimate

Cost Effectiveness: High ($95 M)

There were several key differentiators between
the SL3 Extension to Sullivan and the other
SL3 Extension alternatives, described in theparagraphs below.
While the existing part-time, side-running bus
lanes on Upper Broadway in Everett havehelped ease some of the congestion during
the peak commute hours along the Broadway
corridor, transit users still face tremendous
congestion, amounting to thousands of daily
passenger minutes in delay between Chelsea
Street and Sweetser Circle alone, due to thepart-time nature of this investment.1
The SL3 LPA would provide full-time dedicatedbus lanes along 80% of its alignment andtransit signal priority at 14 intersections,providing travel times that are faster and morereliable than drive-alone times. With dedicatedtransit lanes, Silver Line vehicles are notvulnerable to the traffic congestion experienced
in the adjacent general-purpose lanes. The
level of transit priority achieved under the LPA ishigher than for any of the other SL3 Extension
alternatives. Studies2 have shown that travel
time reliability is as important to riders as total
travel time, and in some cases more important.
Reliability is especially important for workers
operating on a time clock and for families who
must pick up children at a specific time, like somany in Everett and Chelsea.
In addition, other local bus routes that operate
along the alignment can benefit from the bus
lanes. These include MBTA Routes 97, 104,
105, 109, 110, and 112, several of whichhave among the MBTA’s highest and mostresilient ridership. On average, the proposed
infrastructure could save each transit rider threedaily minutes in delay – a substantial travel timesavings, and important to the region from atransit equity perspective. This is higher thanany of the other SL3 Extension alternatives.
The existing MBTA bus routes that operate
along this alignment are more likely to serve
people of color, people without access to avehicle, and people with lower incomes.

1 MBTA Winter 2020
2 The Transit Capacity and Quality of Service Manual is one ofmany studies that document the importance of transit travel time
reliability. See Chapter 6 https://onlinepubs.trb.org/onlinepubs/tcrp/
tcrp_rpt_165ch-06.pdf.

54

MBTA Silver Line Extension Project Final Report55

Locally Preferred Alternative

Next Steps

likely to use, ahead of connections to theOrange Line via Malden Center or Wellington .
Over 55% of respondents to the feedback
form said they were either “extremely likely” or“likely” to use Alternative 3, whereas only 23%
responded the same for Alternative 1 and 43%
for the Alternative 2 . Many respondents alsooffered comments that Alternative 3 would

provide the greatest benefit due to its ability toallow riders to connect to other communities
and transit lines, as well as the extent that
it would operate primarily on transit priority
infrastructure relative to the other alternatives.

“Sending the SL3 to Sullivan gets a key connection withthe other ring bus routes. Plus, it gives a ton of bus
connections to Chelsea and Everett residents.”-Feedback Form Respondent

Next StepsThe LPA has been developed to the conceptual
design level based on GIS mapping, aerial
imagery, and limited field measurements. The
conceptual design illustrates the intended
cross sections and overall transit infrastructure
along the alignment. Those conceptual plans
will need to undergo more detailed engineering
based on professional field survey, including
detailed utility and right-of-way information.
The overall steps in the design process will
include data collection for: survey data,utilities, property information, etc.; traffic
count information; and existing and proposed
traffic signal and roadway plans. The existing
conditions information will inform the detailed
analysis and design process with traffic analysisof existing and proposed conditions anddevelopment of preliminary and final designplans built upon the survey data.
The specific process for engineering eachsegment will vary based on roadway jurisdiction
and funding source. For the SL3 LPA, thealignment falls on MBTA right-of-way androadways under the jurisdiction of Everett andBoston, with a short segment under MassDOT
jurisdiction (Sweetser Circle). Coordination
with MassDOT will also be required for theintersection of Spring Street and Revere Beach
Parkway (Route 16) as Route 16 is under
MassDOT jurisdiction. Similar coordination will
be required with the City of Chelsea for the
crossing of the commuter rail right-of-way at
Third Street. However, if MassDOT-Highway
funding is used for construction, the design will
be required to follow MassDOT’s process andstandards regardless of roadway jurisdiction.
Elements of the project may also be
implemented in phases, allowing Silver Lineservice to commence earlier, but this requires
transit vehicles to use existing roadway
infrastructure. Early implementation elements
may include improvements to signal timing or

56

implementation of signal priority that would
require review and approval by the appropriate
agency or municipality.
While extending Silver Line service beyond
the Orange Line to either Kendall Square or
downtown Boston provides potential ridershipbenefits, further study and the completion of
ongoing planning efforts by others is required
to determine the feasibility of implementing a
Silver Line service to either location. Moreover,this study found that procuring additional
Silver Line vehicles, and expanding vehicle
maintenance and storage capacity would be
required. A future study should consider thefollowing:
1.	 The ridership analysis should model thepotential ridership using the Redesigned
Bus Network that is currently being
implemented by the MBTA;
2.	 Further work be done on the Rutherford
Avenue redesign effort and the Gilmore
Bridge project to better understand thepotential for bus priority lanes withinroadway infrastructure right of way; and3.	 More work be done to evaluate transit
priority initiatives within Kendall Squarespecifically.
In the near term, Bus Network Redesign will
implement high frequency bus services fromChelsea to the Orange Line, and Sullivan
Square to Kendall Square, creating theconnections evaluated in this study to build
market demand. Transitioning to Silver Line will
be dependent on future operational resources,
and fleet and on-street capital investments.

MBTA Silver Line Extension Project Final Report

57

58

MBTA Silver Line Extension Project Final Report59