HNTB Corporation
The HNTB Companies
Engineers Architects Planners
31 St. James Avenue, Suite 300
Boston, MA 02116
Telephone (617) 542-6900
Facsimile (617) 428-6905
www.hntb.com
TECHNICAL MEMORANDUM
TO:
Steve McLaughlin, MassDOT
Paul King, MassDOT
FROM:
Andrea d’Amato, AICP, HNTB
DATE:
November 4, 2011
SUBJECT:
Summary of MOEs for the Casey Overpass At-Grade and Bridge Alternatives
INTRODUCTION
This memorandum summarizes the development and findings for the measures of evaluation (MOEs) for three
(3) Mobility Goals with eight (8) Objectives and three (3) Livability Goals with seven (7) Objectives previously
established by the Casey Overpass Working Advisory Group (WAG). The MOEs for each objective is
described and calculated for each of the two selected Alternatives and compared with existing conditions for
context purposes only. This is a working draft of the results for discussion with members of the WAG.
The information contained within is prepared for review by the WAG at the November 9, 2011 meeting.
THE STUDY AREA
The study area is defined differently for the At-Grade and Bridge Alternative, with the former including the area
along the South and Washington Street Corridor, west of the Forest Hills Station. The boundaries of each
alternative are included on Map of Alternative Boundaries as illustrated, respectively. It is important to note
that for the purposes of the MOE evaluation the same base area of 25.82 acres was used for the spatial
calculations for Existing, Bridge and At-Grade Alternatives (see Appendix for area maps and spatial
calculations).
Both Alternatives include different configurations for Shea Circle but these are interchangeable and are only
presented with each alternative to illustrate the possible variations.
DEVELOPMENT OF THE MOEs
The definition of the MOEs began in April of 2011 through a series of Working Group and Public Meetings.
The formation of: the guiding principles, mobility and livability goals and objectives, and measures, were
determined working closely with the WAG during break-out sessions and revised over the past six (6) months
based on ideas and suggestions provided by the WAG members. The process to develop and refine the MOEs
is summarized below.
Development of Guiding Principles, Goals and Objectives:
April, 20, 2011
Guiding Principles: 4 were presented
Developing a Common Platform: 4 Goals for Mobility and 6 Goals for Livability were presented.
May 4, 2011
Guiding Principles: 4 new principles were added, for a total of 8 Guiding Principles. The guiding principles for
the MOEs were established by the WAG on May 4, 2011. These principles formed the basis for the Fatal Flaw
Analysis used to evaluate a series of Alternative Concept Designs.
Table #1: MOE Guiding Principles
1. Improve SAFETY for all users.
5. Integrate artistic elements in designs.
2. Improve quality of life for residents.
6. Adopt the principles of Universal Design
(accessible and barrier-free design).
3. Address a structurally deficient bridge.
7. Protect and respect the design for Arborway
Yard.
4. Strive to have an inclusive process for the
sharing of information.
8. Develop alternatives that meet ABP budget and
schedule.
Objectives: Revised and consolidated from a total of 10 to 6 objective: 3 Mobility and 3 Livability objectives.
On May 18, 2011 the following “Common Platform” was presented at a Public Meeting and Open House on the
project. WAG members presented each of the goals to the general public.
Developing a Common Platform Mobility and Livability Goals
MOBILITY: The ability to reach a destination and to use, choose and transfer modes within reasonable time
and costs. Mobility is higher when average travel times, variations in travel times, and travel costs are low. The
provision of multi-modal opportunities is essential for good mobility.
LIVABILITY: The use of transportation investments to improve the standard of living, the environment, and
quality of life for all communities. Livable communities are places where transportation, housing and
commercial development investments have been coordinated so that people have access to adequate,
affordable and environmentally sustainable travel options.
Goals:
• Improve roadway geometry to enhance circulation for modes and users.
• Improve access, modal and intermodal local and regional corridor connections to promote
transportation choices.
• Remove barriers for neighborhood connections and integrate transit into economic centers and
residential areas.
• Integrate sustainability into design concepts.
• Create a destination and sense of place and celebrate the area’s architectural, transportation and open
space history.
• Improve the visibility, connectivity and access to gateway open spaces.
Objectives:
The WAG then identified 93 Objectives for each of the 6 Goals as follows.
• Improve roadway geometry to enhance circulation for modes and users. – 21 objectives
• Improve access, modal and intermodal local and regional corridor connections to promote
transportation choices – 14 objectives
• Remove barriers for neighborhood connections and integrate transit into economic centers and
residential areas – 21 objectives
• Integrate sustainability into design concepts – 11 objectives
• Create a destination and Sense of Place and celebrate the area’s architectural, transportation and open
space history – 17 objectives
• Improve the visibility, connectivity and access to gateway open spaces – 9 objectives
Prepared by HNTB for Review on November 4, 2011
Page 2
June 2, 2011
The Guiding Principles were used as Fatal Flaw criteria to evaluate and eliminate a number of HNTB design
team at-grade and bridge concepts, including concepts and designs put forward in previous studies and plans
for the area.
Refining the Objectives and Developing the Measures:
Based on extensive review, analysis and refinement, the HNTB design team evaluated the 93 objectives to
eliminate duplication, identify data sources and test the viability of quantifying those measures with the purpose
of developing measurable objectives with existing and reliable data sources.
June 14, 2011
The WAG was presented with a reduced number of measurable objectives to evaluate and refine with a goal of
selecting between 12 to 15 measures. The group then evaluated the 19 measures developed by the HNTB
design team for further input and modifications. These were presented to the public on June 29, 2011.
Table #2: Goals & Measurable Objectives (Target: 2-3 measures/objective – 12 - 15 Total)
Goals
Original
Objectives
Measurable
Objectives
Improve roadway geometry to enhance circulation for all
modes and users.
21
5
Improve access, modal and intermodal local and regional
corridor connections to promote transportation choices
14
3
Remove barriers for neighborhood connections and
integrate transit into economic centers and residential
areas
21
3
Integrate sustainability into design concepts
11
4
Create a destination and Sense of Place and celebrate the
area’s architectural, transportation and open space history
17
2
Improve the visibility, connectivity and access to gateway
open spaces
9
2
Total
93
19
July 19 & 27; August 31, 2011
Over the course of July and August, WAG members made comments, suggestions and revisions to the MOEs.
Members were provided at each meeting the documentation of how selected measures were treated and
refined.1 The measures were tested based on available data and reduced further. The MOEs were presented
at the September 13, 2011 public meeting and open house.
1
For a complete review of all the meeting presentations, working group comments and documents, please see the MassDOT website at
www.massdot.state.ma.us/caseyoverpass/
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Page 3
Summary of the Process to Date:
As the design of the alternatives progressed with further input from the WAG and reduced to two (2): an AtGrade and Single Bridge Alternatives, the MOEs were also further modified, refined and tested based on both
input from the WAG and Existing Conditions calculations. Three measures were deleted and 4 measures were
added, and others were further modified to clarify intent and available data that could yield meaningful results.
Minor adjustments were made to a number of other measures to clarify the objectives and remove
unnecessary repetition.2 The final Distribution of MOE goals, objectives and measures are summarized in the
Table #3.
Table #3: Distribution of Mobility & Livability MOEs
MOEs
Mobility
Livability
Total
Goals
3
3
6
Objectives
9
7
16
Measures
16
15
31
The final MOEs and their respective calculations are detailed in detail below.
THE FINDINGS: WORKING DRAFT FOR DISCUSSION PURPOSES ONLY
Methodology and Working Assumptions for MOE Calculations
While some measurements for the MOEs for the Livability Objectives are straightforward, many are not. This
document describes the methodology used and assumptions on which many of the measurements are based.
Because many of these measurements represent visual qualities, diagrams are included as an aid at the end
of this document to illustrate the spatial characteristics between the alternatives.
The level of detail is based on the need to determine the differences between the existing conditions and the
two alternatives in order to score each measure on its own merits. The following list details the methodology,
assumptions and measures used to calculate Existing Conditions, the At-Grade Alternative and the Single
Bridge Alternative. Again, it is important to note that for the purposes of the MOE evaluation the same base
area of 25.82 acres was used for the spatial calculations for Existing, Bridge and At-Grade Alternatives.
The Evaluation
Goal #1: Improve Roadway Geometry to Enhance Circulation for all Modes and Users
1.01 Objective: Minimize local street impacts of cut through traffic (e.g., minimize local diversions)
Measure: Changes in forecast traffic volumes on key local streets.
1 Reduction in forecast traffic volume
0 Forecast traffic volume remains the same
-1 Increase in forecast traffic volume
Data Source: 2011 CTPS model
2
Deleted measures: 3.01 allows curb access to development (required by all development and therefore not relevant); 5.01 design solution creates
sense of place (not measurable); 6.01 area of shadow cast by bridge (redundant – already measured in 6.01b). Additions: 5.01b clarifying “open space”
uses more clearly from contiguous to adjacent; 5.01d non-peak travel speeds was added per WAG request; 5.02b measuring proximity to new
development; 6.02a and 6.02b to reflect WAG request to have a measure for the Emerald Necklace. Eleven MOEs were modified to clarify intent and
distinguish each measure from the other.
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Assumptions/Comments: The model demonstrated minimal impact in travel –time alternate routes take
longer to travel.
Existing Conditions:
Serves as the baseline for this measure.
At-Grade Alternative:
No change in traffic volumes or patterns forecast
Bridge Alternative:
No change in traffic volumes or patterns forecast
Existing At- Grade Bridge
0
0
0
1.02a Objective: Enhance pedestrian and bicycle environment – north-south movements
Measure: Projected pedestrian level of services (PLOS)
1 PLOS A or B
0 PLOS C or D
-1 PLOS E or F
Data Source: Urban Facility Analysis
Assumptions/Comments: The analysis demonstrated that the overall pedestrian experience along the
corridor is improved over existing and similar for both alternatives. The analysis assumes all pedestrian
crossings are at designated intersections.
Note: Current methodology for analyzing pedestrian movements is ineffective in differentiating among
the alternatives. Exploring new criteria that will capture crossing times and pedestrian travel
distances.
Existing Conditions:
PLOS is an overall C
At-Grade Alternative:
PLOS is an overall C
Bridge Alternative:
PLOS is an overall C
Existing At- Grade Bridge
0
0
0
1.02b Objective: Enhance pedestrian and bicycle environment – north-south movements
Measure: Type and quality of off-street bike path
1 Separate bicycle and pedestrian paths
0 Combined multiuse path
-1 Sidewalk only
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Quantitative inventory of bicycle amenities demonstrated that the at-grade
alternative offers bike lanes along Washington Street.
Existing Conditions:
Outside of the Southwest Corridor Park, there are no existing off-street bike paths within the study area
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At-Grade Alternative:
Includes a complete off-street bike path network, including a north-south connection along
Washington Street, west of Forest Hills Station.
Bridge Alternative:
Does not include a north-south off-street bike path and makes no additional enhancements along
Washington / South Streets Corridor.
Existing At- Grade Bridge
-1
1
-1
1.02c Objective: Enhance pedestrian and bicycle environment – north-south movements
Measure: Projected bike level of services (BLOS) – On-street
1 BLOS A or B
0 BLOS C or D
Data Source: 2011 Urban Facility Analysis
-1 BLOS E or F
Assumptions/Comments: The Bicycle Capacity Analysis demonstrated that the overall bicycle experience
for north south movements is improved over existing and similar for both alternatives based on the new
designs including on-street bike lanes for both alternatives.
Existing Conditions:
There are limited bicycle amenities running north-south within the study area. The Southwest Corridor
Park extends north of the study area.
At-Grade Alternative:
Includes on-street bike lane along the New Washington Street Corridor and off-street bike lanes along
the Washington/South Street Corridor.
Bridge Alternative:
Although on-street bikes lanes are provided along the New Washington street corridor, it does not
include improvements along Washington/South Street Corridor.
Existing At- Grade Bridge
-1
0
0
1.03a Objective: Enhance pedestrian and bicycle environment – east-west movements
Measure: Projected pedestrian level of services (PLOS) – On-street
1 PLOS A or B
0 PLOS C or D
-1 PLOS E or F
Data Source: 2011 Urban Facility Analysis
Assumptions/Comments: The analysis demonstrated that the overall pedestrian experience along the
corridor is improved over existing and similar for both alternatives. The analysis assumes all pedestrian
crossings are at designated intersections.
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Note: Current methodology for analyzing pedestrian movements is ineffective in differentiating among
the alternatives. Exploring new criteria that will capture crossing times and pedestrian travel
distances.
Existing Conditions:
PLOS is an overall C
At-Grade Alternative:
PLOS is an overall C
Bridge Alternative:
PLOS is an overall C
Existing At- Grade Bridge
0
0
0
1.03b Objective: Enhance pedestrian and bicycle environment – east-west movements
Measure: Type and quality of off-street bike path
1 Separate bicycle and pedestrian paths
0 Combined multiuse path
-1 Sidewalk only
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Quantitative inventory of bicycle amenities demonstrated that the off-street bike
paths are improved over existing and similar for both alternatives.
Existing Conditions:
There are no existing east-west off-street bike paths within the study area
At-Grade Alternative:
Includes a complete off-street bike path network
Bridge Alternative:
Includes a complete off-street bike path network
Existing At- Grade Bridge
-1
1
1
1.03c Objective: Enhance pedestrian and bicycle environment – east-west movements
Measure: Projected bike level of services (BLOS) - On-street
1 BLOS A or B
0 BLOS C or D
-1 BLOS E or F
Data Source: Urban Facility Analysis
Assumptions/Comments: The Bicycle Capacity Analysis demonstrated that the overall bicycle experience
for east-west movements is improved over existing and similar for both alternatives based on the new designs
including on-street bike lanes for both alternatives.
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Existing Conditions:
There are no bicycle amenities running east-west within the study area.
At-Grade Alternative:
Includes improvements along New Washington Street with an on-street bike lane
Bridge Alternative:
Includes improvements along New Washington Street with an on-street bike lane
Existing At- Grade Bridge
-1
0
0
1.04a Objective: Improve roadway and intersection operations for vehicles
Measure: Vehicle level of service (LOS) and overall delay
1 Surface street network delay decreases
0 Surface street network delay unchanged
-1 Surface street network delay increases
Data Source: Intersection Capacity/Queuing Analysis and VISSIM simulations
Assumptions/Comments: The analyses demonstrated that the overall travel experience along the corridor is
improved over existing and similar for both alternatives. The vehicular LOS does include bus operations to
points of destination and Arborway Yard. Buses will be provided queue jumping and priority signalization.
Existing Conditions:
Serves as the baseline for this measure
At-Grade Alternative:
Surface street network delay decreases
Bridge Alternative:
Surface street network delay decreases
Existing At- Grade Bridge
0
1
1
1.04b Objective: Improve roadway and intersection operations for vehicles
Measure: Simplify network - number of turns between specific destinations
1 All turns made at most direct location
0 Minimal turn restrictions with alternate route provided within project limits
-1 Multiple turn restrictions, alternate route not provided
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Designs for both alternatives create a new roadway configuration, address
complicated intersections and improve signalization for all movements.
Existing Conditions:
Existing surface roadway configuration is confusing and requires circuitous routes to make specific
connections along east-west direction.
At-Grade Alternative:
Minimal turn restrictions with alternate route provided within project limits
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Bridge Alternative: All turns made at most direct location
Existing At- Grade Bridge
-1
0
1
Goal #2: Improve Access, Modal and Intermodal Local and Regional Corridor Connections to Promote
Transportation Choices
2.01 Objective: Maintain or improve surface loading points for passenger vehicles and taxis at Forest
Hills Station
Measure: Access to Forest Hills Station loading areas.
1 Curb side loading/unloading area increased
0 Curb side loading/unloading area maintained
-1 Curb side loading/unloading area decreased
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Linear feet of dedicated curb-side pick-up and drop-off space along the perimeter
of Forest Hills Station. Space for taxi and passenger vehicle is not differentiated since that is a policy issue of
what types of vehicles can stop where. This is a measure of the physical space provided.
Note: The pick-up/drop-off area on Hyde Park Avenue is not within the boundary for measurements
but was included in the total for consistency.
Existing Conditions:
795 LF total
Drop off provided only on New Washington and Lower Deck areas of the station and taxis allocated
space on both sides – upper and lower deck of the station.
At-Grade Alternative:
995 LF total
Bridge Alternative:
630 LF total
Existing At- Grade Bridge
0
1
-1
2.02a Objective: Improve bicycle and pedestrian access and overall connectivity
Measure: Connectivity of bike paths - quality of connections.
1 Provides continuous off-street bike connections to existing networks
0 Provides a mix of on-street and off-street connections
-1 Does not provide off-street connections
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Quantitative inventory of bicycle amenities demonstrated that both alternatives
improve connectivity of bike paths over existing and at-grade alternative offers off-street bike paths along
Washington Street.
Existing Conditions:
There are currently no on-street bicycle lanes in the study area. The Southwest Corridor Park provides
Prepared by HNTB for Review on November 4, 2011
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the only off-street bicycle path in the study area which terminates at New Washington Street.
At-Grade Alternative:
Provides on-street bicycle lanes and off-street bicycle paths along the length of the corridor. The area
along Washington Street between South Street and Ukraine Way is still under study and, in the
current plan there is room for either an on-street bicycle lane or an off-street bicycle path, but not both.
Bridge Alternative:
Provides on-street bicycle lanes and off-street bicycle paths along the length of the corridor. The area
along Washington Street, south of the Arborway, remains in the existing condition with no
improvements.
Existing At- Grade Bridge
-1
0
0
2.02b Objective: Improve bicycle and pedestrian access and overall connectivity
Measure: Number of lanes crossed north/south movement
1 Two or less
0 Three
-1 More than Three
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: The measure is the number of lanes crossed between pedestrian refuge areas
(e.g., medians).
Existing Conditions:
More than three lanes crossed in each direction and current median is not sufficiently wide enough to
provide pedestrian refuge. NO pedestrian crossing allowed western side of the New
Washington/Washington/Hyde Park street intersection.
At-Grade Alternative:
3 lanes crossed before median refuge is reached. Intersection designs allow for crossings on all
approaches for bikes and pedestrians.
Bridge Alternative:
2 lanes crossed before median refuge is reached. Intersection designs allow for crossings on all
approaches for bikes and pedestrians.
Existing At- Grade Bridge
-1
0
1
2.02c Objective: Improve bicycle and pedestrian access and overall circulation
Measure: Minimum sidewalk width
1 Sidewalk width meets or exceeds minimum
0 Sidewalk width meets or exceeds minimum with modest constraints in sidewalk width
-1 Sidewalk width is at or below minimal requirements
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Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Design Plans illustrate that the sidewalk width is improved over existing and
similar for both alternatives. Width is assumed at a minimum of 8’ for new design area except where noted
below.
Note: Sidewalks in heavily traveled areas, such as around the MBTA station, will likely be wider, or may
be incorporated into a plaza area.
Existing Conditions:
Sidewalk width varies with the majority of the sidewalks between 7 feet and 8 feet. The north side of
New Washington Street is wider: up to 15.5 feet east and west of the drop-off area.
At-Grade Alternative:
Minimum sidewalk width is 8 feet. The exception is along Washington Street just north of Ukraine
Way where the sidewalk width is currently set at 6 feet adjacent to an 8-foot off-street bicycle path.
Bridge Alternative:
Minimum sidewalk width is 8 feet. Again, the exception is along Washington Street where the
existing conditions will remain – that is approximately 7 feet on the west side and 8 feet on the east
side of the street. No improvements are proposed along Washington Street below South Street.
Existing At- Grade Bridge
-1
1
1
2.03a Objective: Improve bus operations
Measure: Bus travel times
1 Overall bus travel times decreased
0 Overall bus travel times maintained
-1 Overall bus travel times increased
Data Source: Traffic Analysis and Design Plans
Assumptions/Comments: Queue jump lanes will be provided at New Washington Street intersections.
Overall travel-time improvements along the corridor offset the added travel distance for bus 39 under the
alternatives.
Existing Conditions:
Serves as the base line for this measure
At-Grade Alternative:
Overall bus travel times maintained
Bridge Alternative:
Overall bus travel times maintained
Existing At- Grade Bridge
0
Prepared by HNTB for Review on November 4, 2011
0
0
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Goal #3 Remove Barriers for Neighborhood Connections and Integrate Transit into Economic Centers
and Residential Areas3
3.01 Objective: Support Access to Future Development
Measure: Strengthen Neighborhood Sight Line Connections (N/S)
1 Allows for direct visual sight line connectivity
0 Modest visual connectivity
-1 Physical barrier blocking visual connectivity
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Views will be greatly improved over today under the at-grade alternative, modestly
for bridge alternative.
Existing Conditions:
North-south sight lines obstructed by bridge
At-Grade Alternative:
No sight line obstructions
Bridge Alternative:
reduced from existing
North-south sight lines obstructed by bridge, but bridge height and length
Existing At- Grade Bridge
-1
1
0
3.02 Objective: Promote modal connections that reduce use of personal vehicles
Measure: Areas created for transit connections
1 Significant new area created for improved intermodal connections that
reduce the need and use of personal vehicles
0 Limited new area created for improved intermodal connections that reduce
the need and use of personal vehicles
-1 No new area created for improved intermodal connections that reduce the
need and use of personal vehicles
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Both alternatives provide for reconfiguration of the north side of the MBTA station
and the Route 39 bus loading /unloading area. At-grade alternative includes reconfiguration of Washington
Street south of Arborway; Bridge alternative maintains the existing condition in this area.
Existing Conditions:
No new area created for improved intermodal connections that reduce the need and use of personal
vehicles
At-Grade Alternative:
Significant new area created for improved intermodal connections that reduce the need and use of
personal vehicles
3
The measure “Access to Future Development- Allows curb access to development parcels” was removed as neither design alternative obstructs
access to any parcel and therefore lost its value in differentiating among the alternatives.
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Bridge Alternative:
Limited new area created for improved intermodal connections that reduce the need and use of
personal vehicles
Existing At- Grade Bridge
-1
1
0
Goal #4: Integrate Sustainability into Design Concepts
4.01 Objective: Number of net trees planted in the study area
Measure: Net increase in the number of trees in the corridor
1 Increases number of trees by 100 or more
0 Increases number of trees by less than 100
-1 Does not increase number of trees
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: For this calculation the existing trees were counted based on survey information.
The number of trees removed was estimated based on the alternatives. New trees planted were estimated
based on the alternatives.
Existing Conditions:
263 Total
At-Grade Alternative:
370 Total; 107 net increase
Bridge alternative:
320 Total; 57 net increase
Existing At- Grade Bridge
-1
1
1
4.02a Objective: Minimize adverse water and light impacts
Measure: Manage storm water run-off
1 Significantly reduces the sf of impervious surface to accommodate storm
water management
0 Moderately reduces the sf of impervious surface to accommodate storm
water management
-1 Does not reduce the sf of impervious surface to accommodate storm
water management
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This calculation identifies permeable and impermeable surfaces and states
permeable surfaces as a percentage of total area. Roadways, sidewalks, bicycle paths, plaza areas are
considered impermeable. All grassed or planted areas area considered permeable.
For the purposes of this analysis, the MBTA plaza is considered 50% permeable for the existing condition
and 25% permeable for both alternatives to allow increased hard surface for circulation and programmed
activities.
Non-roadway areas under the bridge are assumed to be impermeable. Bridge decking is not included in this
calculation since the areas under the bridge are already counted.
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Existing Conditions:
33% of total area is permeable
At-Grade Alternative:
40% of total area is permeable
Bridge alternative:
39% of total area is permeable
Existing At- Grade Bridge
0
1
1
4.02b Objective: Minimize light pollution
Measure: Minimize Light Pollution. Estimated amount of light pollution based on location, height, and area
illuminated.
1 Light pollution decreases moderately
0 Light pollution decreases minimally
-1 Light pollution remains constant
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: The working assumption is that for either alternative, new lights will be state-ofthe art LED fixtures that are full cut-offs in order to minimize light pollution. The lights for the surface streets
in both alternatives will be similar in type and number consistent with DCR policy and guidelines. The
greatest source of light pollution will be from fixtures on the bridge which are higher and can be seen from a
greater distance.
Note: The design of the lighting (location and type) will occur during the 25% design phase.
Existing Conditions:
Significant light pollution
At-Grade Alternative:
No bridge lights
Bridge alternative:
Reduced light pollution
Existing At- Grade Bridge
-1
1
0
4.03 Objective: Initial and life-cycle costs
Measure: Construction cost plus maintenance cost
1 Low cost
0 Medium cost
-1 High cost
Data Source: Design Team Cost Estimate of construction and maintenance costs.
Assumptions/Comments: The surface street network for both alternatives will be a similar order of
magnitude for both construction and maintenance. The additional amenities associated with the at-grade
alternative increase the initial construction costs. The bridge adds to the construction cost for the bridge
alternative and the maintenance for the bridge will add significantly to the overall life-cycle costs.
Note: Cost estimates for At-Grade Alternative assume capital costs for reconstruction of MBTA vent
stacks, commuter rail grates, Orange Line head house, and improvements to the Washington/South
Street area and improvements to the upper loading deck of the MBTA station.
Existing Conditions:
High life cycle cost due to maintenance
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At-Grade Alternative:
Moderate life-cycle cost
Bridge alternative:
High life-cycle cost
Existing At- Grade Bridge
-1
0
-1
Goal #5: Create a Destination and Sense of Place and Celebrate the Area's Architectural,
Transportation and Open Space History
5.01a Objective: Increase space for community gatherings or activities and create a sense of place
(e.g., parks, farmers/artists markets, outdoor public gathering space, or similarly uses)
Measure: Total amount of usable contiguous space
1 Large increase in usable contiguous space
0 Modest increase in usable contiguous space
-1 Minimal increase in usable contiguous space
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Area was calculated by using the total area within the boundary and subtracting
roadway areas, medians and traffic islands, and non-roadway areas under the bridge. The measure assumes that the off-street bike and pedestrian pathways, hard and soft open space areas create opportunities for active and passive uses. Total area used in the spatial calculation is 25.82 acres.
Existing Conditions:
10.5 Acres (or 41%)
At-Grade Alternative:
13.7 Acres (or 53%)
Bridge Alternative:
16.1 Acres (or 62%)
Existing At- Grade Bridge
0
1
1
5.01b Objective: Increase space for community gatherings or activities and create a sense of place
(e.g., parks, farmers/artists markets, outdoor public gathering space, or similarly uses)
Measure: Total amount of usable open space directly connected to, or abutting existing and future land
uses
1 Large increase in connected/adjacent open
0 Modest increase in connected/adjacent open
-1 Minimal increase in connected/adjacent open
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This is a subset of the “total amount of usable contiguous space”. It is defined
as potentially usable area directly connected to a land use that could benefit from the additional space. For
example, new land created at the entrance to Franklin Park would benefit from the open area for visibility
and associated uses or new land around the MBTA could allow the plaza to be utilized for ancillary
purposes.
Existing Conditions:
3.9 acres (or 15%)
At-Grade Alternative:
8.0 acres (or 30%)
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Bridge Alternative:
7.6 acres (or 29%)
Existing At- Grade Bridge
-1
1
1
5.01c Objective: Increase space for community gatherings or activities and create a sense of place
(e.g., parks, farmers/artists markets, outdoor public gathering space, or similarly uses)
Measure: Creation of areas for community gatherings
1 Significant opportunities for community spaces or uses
0 Modest opportunities for community spaces or uses
-1 No opportunities for community spaces or uses
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This is a subset of the usable areas defined in Measure 5.01a. It includes the
areas in the rotary at Shea Circle. Not included are areas less than 10,000 SF: which is assumed to be the
smallest programmable space (approximately a quarter of an acre). Also not included are areas primarily used
for sidewalks and bicycle paths such as the parcels abutting the proposed Arborway yard MBTA facility.
Existing Conditions:
4.8 Acres (or 19%)
At-Grade Alternative:
7.0 Acres (or 27%)
Bridge Alternative:
7.6 Acres (or 29%)
Existing At- Grade Bridge
0
1
1
5.01d Objective: Increase space for community gatherings or activities and create a sense of place
(e.g., parks, farmers/artists markets, outdoor public gathering space, or similarly uses)
Measure: Off-peak vehicles speeds
1 Predicted off-peak speeds less than 30 mph
0 Predicted off-peak speeds between 30-40 mph
-1 Predicted off-peak speeds greater than 40 mph
Data Source: Existing Off-Peak Speed measurements and Design Plans
Assumptions/Comments: Vehicle speeds during off-peak or free flow, conditions are expected to vary based
on the infrastructure type and specific design details. Off-peak measurements of existing vehicle speeds were
conducted to identify operating speeds for each of the existing infrastructure elements: bridge, surface roads,
and ramps. These speeds were reviewed and applied to the alternatives to develop estimates of off-peak
speeds.
Existing Conditions: Existing measurements show speeds on the Casey Overpass and on the ramps
connecting to surface streets averaged 30-35 mph. Surface street speeds averaged approximately 25 mph.
At-Grade Alternative: Speeds on the proposed surface streets are expected to be similar to existing
measured surface street speeds of approximately 25 mph.
Bridge Alternative: Speeds on the proposed bridge and ramps connecting to the surface roadways, including
Shea Circle, are expected to be comparable to measured speeds of 30-35 mph on the Casey Overpass and
ramps.
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Existing At- Grade Bridge
0
1
0
5.02a Objective: Enhance value of commercial and residential buildings through improved visual or
aesthetic changes.
Measure: Visual identification of community resources and features
1 Improved view corridors to identify and locate key community resources
and features
0 Minimal change in current views
-1 Diminished view corridors - blocking community resources and features
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This measures locations where views across the corridor are blocked by bridge
abutments, approach structures and piers. Although pier locations and size have not been calculated for the
Bridge Alternative, for the purposes of this analysis six 48-inch piers (4’ diameter columns with spans of
approximately 150-200’ and 1 column per span) were assumed to support the new bridge.
The result of this measurement is given as a percentage of the corridor length, from the Forest Hills Gate at the
Arboretum to Shea Circle, which is clear of obstructions.
Existing Conditions:
61 % Clear
At-Grade Alternative:
100% Clear
Bridge alternative:
75% Clear
Existing At- Grade Bridge
-1
1
0
5.02b Objective: Enhance value of commercial and residential buildings through improved visual or
aesthetic changes.
Measure: Proximity of roadway to residences
1 Roadways are further from residential properties
0 Roadways are the same distance from residential properties
-1 Roadways are closer to residential properties
Data Source: Design Plans and Existing Conditions Survey (See Figure 3)
Assumptions/Comments: Measurement of the distance from residential buildings to the curb line of adjacent
roadways. Note, the frontage road adjacent to the courthouse is considered as a driveway and the main
roadway beyond is used as the measurement. Five buildings were identified as the closest to the corridor. The
building used in the Hampstead neighborhood is representative of a row of houses adjacent to the roadway.
The building shown in the Asticou neighborhood is the closest to the roadway.
Existing Conditions:
See Figure 3
At-Grade Alternative:
See Figure 3
Bridge alternative:
See Figure 3
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Existing At- Grade Bridge
0
0
0
5.02c Objective: Enhance value of commercial and residential buildings through improved visual or
aesthetic changes.
Measure: Orientation of building facades to enhance interactions and connectivity to residential and
commercial development
1 Encourages buildings to orient towards the corridor
0 Does not influence a primary orientation
-1 Discourages buildings from orienting towards the corridor
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This measures the level of desirability for new development to orient toward the
corridor rather than the crossing street. This applies principally to the LAZ lot and the Arborway Yard
development along Washington Street.
Existing Conditions:
Discourages frontage on corridor
At-Grade Alternative:
Encourages frontage on corridor
Bridge alternative:
Somewhat discourages frontage on corridor
Existing At- Grade Bridge
-1
1
-1
Goal #6: Improve the Visibility, Connectivity and Access to Gateway Open Spaces
6.01a Objective: Enhance visual quality - Increase open vistas, views, view corridors and access to
light and air
Measure: Measure of visual quality (vistas and view corridors) along and across the corridor.
1 No visual obstructions or shadows
0 Modest visual obstructions or shadows
-1 Significant visual obstructions or shadows
Data Source: Design Plans and Existing Conditions Survey (See Figure 4)
1. Assumptions/Comments: This analysis looks at five important community resources along the
corridor and evaluates how their views are impacted by bridge abutments from a variety of angles.
The five resources include the following.
2. Entrance to Franklin Park at Shea Circle
3. Courthouse
4. MBTA station – north entrance and tower
5. Southwest Corridor Park
6. Arboretum as defined as the tree line at the northeast corner
The results are stated as a percentage of the “View Shed” that is blocked. The view shed is defined as the
angle of view to a resource at a distance of approximately 500 feet. Five hundred feet is a distance that allows
views directly across the corridor and at some angles.
Although pier locations and size have not been calculated for the Bridge Alternative, for the purposes of this
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analysis six 48-inch piers (4’ diameter columns with spans of approximately 150-200’ and 1 column per span)
were assumed to support the new bridge.
Note: the view to the Arboretum and the MBTA station tower have a vertical component (in addition to
a horizontal component) that has not been calculated, but would not affect the overall findings.
Existing Condition:
The most obstructed views
At-Grade Alternative:
Provides unobstructed views at all locations
Bridge Alternative:
Reduces the amount of obstructed views
Existing At- Grade Bridge
-1
1
-1
6.01b Objective: Enhance visual quality - Increase open vistas, views, view corridors and access to
light and air
Measure: Measure of visual quality (shadows) along and across the corridor at New Washington Street
1 No visual obstructions or shadows
0 Modest visual obstructions or shadows
-1 Significant visual obstructions or shadows
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: This analysis measures the area of shadow under the bridge. While the shadow
will move during the day and seasons it will always be in proportion to the area of the bridge structure. For this
calculation the area of the bridge structure between abutments was used. Additionally, shadows will be cast on
the north side of the abutment and approach ramps, however these shadows were considered minor
compared to the shadow under the bridge and were not included in this calculation.
Existing Conditions:
Area of shadow = 131,022 SF (or 3 .00 acres)
At-Grade Alternative:
No shadows
Bridge alternative:
Area of shadows = 39,735 SF (or 0.91 acres)
Existing At- Grade Bridge
-1
1
0
6.02a Objective: Evaluation of Emerald Necklace Connections
Measure: Strength and quality of the Emerald Necklace connection and reinforcement of Olmsted’s
vision
1 Establishes significant Emerald Necklace connections and significantly
reinforces Olmsted's vision
0 Establishes modest Emerald Necklace connections and does not significantly
reinforce Olmsted's vision
-1 Establishes few, if any, Emerald Necklace connections and does not
significantly reinforce Olmsted's vision
Data Source: Design Plans and Existing Conditions Survey
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Assumptions/Comments: Measures the physical and visual connections along the corridor between the
Arboretum and Franklin Park. Measures the degree to which Olmsted’s vision of 1) separated modes of travel
and 2) regularly spaced rows of trees separating the various mode pathways.
Both alternatives create significant improvements in the Emerald Necklace connection from existing conditions.
The bridge alternative reduces the ability to plant trees in the pattern of Olmsted’s plan.
Note: the intent of this design is not to duplicate the „original Olmsted plan” as much has
changed since its inception. That being said, the intent is to do honor and respect for the
ideals and vision Olmstead had in creating a cohesive corridor of green multi-modal
connections. For example, we will not be duplicating horse drawn carriage ways nor do we
intend to recommend a landscaping design based on mono-culture plantings.
Existing Conditions:
Complete physical and landscaped break in the corridor
At-Grade Alternative:
Strong connection pays attention to modal accommodation and separation and completely connects
the landscaped corridor from the Arboretum and Arborway to Franklin Park and the Cemetery.
Bridge alternative:
Moderate connection as it will have sections of breaks in the landscaped area connections and the
bridge will create a visual barrier obstructing the open space visual resources and connections.
Existing At- Grade Bridge
-1
1
0
6.02b Objective: Evaluation of Emerald Necklace Connections
Measure: Create an opportunity for a central focus point that identifies the area and provides guidance to
local destinations (Emerald Necklace, business areas).
1 Large contiguous central area visible from all angles provided in design
0 Moderate central area visible from all or most angles provided in design
-1 Small central area visible from all or most angles provided in design
Data Source: Design Plans and Existing Conditions Survey
Assumptions/Comments: Focusing on the New Washington Street block between South Street and Hyde
Park Avenue, this criterion measures the ability to see across and along the corridor to significant features
such as existing storefronts, proposed development, the MBTA station and park entrances.
Existing Conditions:
Little opportunity, limited access and visual confusion
At-Grade Alternative:
Significant opportunity
Bridge alternative:
Limited opportunity
Existing At- Grade Bridge
-1
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1
-1
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APPENDIX:
Spatial Calculations