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									Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
December 2008



                       Table of Contents
                       Executive Summary ....................................................................................... 1
                       Traffic.............................................................................................................. 4
                           Alternate Travel Routes & Trip Reassignment....................................... 8
                           Traffic Analysis Results ......................................................................... 14
                       Concurrent Project Combinations............................................................... 20
                          Combination Traffic Analysis Methods................................................. 22
                          Combination Traffic Analysis Results................................................... 24
                          Combination Analysis Summary........................................................... 37
                          Mitigation Measures ............................................................................. 49
                          Mitigation Analysis ................................................................................ 50
                          Mitigation Analysis - Summary ............................................................. 69
                       Study Limitations ......................................................................................... 70
                       Conclusions .................................................................................................. 71
                       Appendix A: Study Limits and Schedule
                       Appendix B: Study Results
                       Appendix C: Combination Analysis Results with Mitigation
                       Appendix D: Combination Analysis Results without Mitigation
                       Appendix E: List of Provided Documentation (See Final Report, Volume II)
                       Appendix F: Existing Traffic Volumes (See Final Report, Volume II)
                       Appendix G: Structure Staging Concepts (See Final Report, Volume II*)
                       Appendix H: Traffic Reassignment Routes
                       Appendix I: Level of Service Analysis Results (Individual Projects)
                       Appendix J: Schedule Detail (Omitted)
                       Appendix K: Condition Summary Reports (See Final Report, Volume II)
                       Appendix L: Anticipated Permitting Status (See Final Report, Volume II)
                       Appendix M: Select Link Analysis (See Final Report, Volume II)
                       Appendix N: Photographs (See Final Report, Volume II)
                       Appendix O: SYNCHRO Analysis Files

                       * The staging concept for the Longfellow Bridge shown in Appendix G,

                       Volume II has not been updated to reflect the staging concept assumed

                       for the purposes of the DCR ABP (i.e. the diversion of all outbound traffic

                       to Cambridge and the restriction of inbound traffic to Boston to one lane).




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                       Executive Summary
                       As the Final Report for the Charles River Basin Infrastructure Study

                       (Study) was being completed, the Commonwealth’s Accelerated Bridge

                       Program (ABP) was enacted on August 4, 2008 via the passing of Chapter

                       233 of the Acts of 2008. The goal of the ABP is to improve the safety and

                       condition of bridges in the Commonwealth with a particular focus on

                       structurally deficient bridges and on bridges projected to become struc-

                       turally deficient in the next eight years. As a majority of the bridges in-

                       cluded in the Study are eligible for funding under the ABP, the Depart-

                       ment of Conservation and Recreation (DCR) reviewed the synchronization

                       schedule developed under the Study (Volume I, Appendix A, Figure A3)

                       and accelerated some of the structures to meet the schedule criteria of

                       the ABP.

                               As a result, the synchronization schedule (now referred to as the

                       Base Line Schedule) was modified by DCR by accelerating the anticipated

                       start of construction on the following five structures:

                               • Cambridge Street (River Street)
                               • Western Avenue
                               • Reid Overpass (Memorial Drive over Brookline Street)
                               • Eliot Bridge
                               • North Harvard Street (Larz Anderson)

                       The schedules for the remaining structures included in the Base Line

                       Schedule either remained the same, or were slightly modified by DCR, to

                       meet the overall goals of their accelerated bridge program. It should be

                       noted that the DCR ABP schedule analyzed in this Study has continued to




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                       evolve and change as the overall priorities and goals of the ABP become

                       clearer.

                                  A majority of information developed and presented in the Final

                       Report (Volumes I and II), provides the background and baseline data for

                       this supplemental study as it relates to the overall Study’s purpose and

                       objective, study area, methods, traffic data collection and analysis

                       methods, and existing traffic conditions. Therefore, the information

                       contained herein only includes that information and those graphics that

                       have changed as a result of a change in an underlying assumption or as a

                       result of the changes to the Base Line schedule.        For proposes of

                       convenience and consistency, the information in this Volume has been

                       arranged in the same format and appendices as the Final Report.

                                  The results of this supplemental study find that the DCR ABP

                       Schedule (Volume III, Appendix A, Figure A3) represents a logical

                       sequence for the rehabilitation of the twelve structures while mitigating,

                       to the extent possible the anticipated traffic congestion. The resulting

                       concurrent rehabilitation projects coupled with possible signal retiming

                       and phasing found two time periods that exhibit the highest levels of

                       unacceptable intersection level of service (LOS). These periods include a

                       6 month period commencing in 2011 and 2 month period commencing in

                       2013. Overall, it was found that the intersections on both sides of the

                       River Street Bridge and the intersection just north of the Craigie Dam

                       Bridge will experience the longest durations of LOS E or F in the AM Peak

                       Hour as a result of combinations of projects under construction. During

                       the PM Peak Hour, the intersections on either side of the Massachusetts




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                       Avenue Bridge will experience the longest duration of LOS E or F as a

                       result of combinations of projects under construction.

                               Should the next phase of the Study be implemented by EOTPW,

                       some of the results obtained may be revised based upon different

                       methodologies utilized to determine traffic re-assignment routes.           In

                       addition, as the results of the Study are presented to the stakeholders

                       and public, additional information may be uncovered or presented. This

                       information as well may have an influence over the results of this Study.




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                       Traffic
                       This section presents the findings of the traffic analyses conducted to

                       evaluate existing conditions, and the phase of construction for each indi-

                       vidual synchronization project which is anticipated to have the most se-

                       vere traffic impact.

                       Traffic Capacity Assumptions
                       The following section will describe the assumptions made related to traf-

                       fic capacity provided during the most serve traffic condition for each of

                       the study projects.

                               Bowker Interchange (Ramp H): During the most severe traffic im-

                       pact stage of construction the Bowker Line A to Storrow Drive westbound

                       will be closed. Line A traffic destined for Storrow Drive westbound would

                       exit to the Charlesgate East surface road, continue along Charlesgate

                       East to the intersection with Beacon Street, and take the Line A on-ramp

                       to access Storrow Drive westbound. This project is currently under con-

                       struction, and no physical improvements to capacity have been included

                       in the traffic management plan for the intersections along the proposed

                       detour route.

                               Craigie Dam Bridge and Drawbridge: The most severe traffic im-

                       pact stage of construction would provide a single travel lane in each di-

                       rection in the area of the Craigie Drawbridge. Since the two structures are

                       closely spaced, traffic capacity restrictions imposed at one structure will

                       effectively be imposed on the other. It was assumed that two-thirds of the

                       inbound traffic and one-half of the outbound traffic would be diverted.

                       Reduction of the inbound roadway to one lane significantly reduces the




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                       queuing space available on the approach to the traffic signals located at

                       Leverett Circle.

                                 Boston University (BU) Bridge: The traffic management plan pro-

                       poses to provide one travel in each direction throughout the duration of

                       construction. It was assumed that 50% of the traffic currently using the

                       bridge would find an alternate route. This equates to a per lane flow rate

                       of approximately 1,000 vehicles per hour per lane. This value would nor-

                       mally be low for an isolated lane, but in this case it is high because the

                       traffic signals located at either end of the bridge control the volume of

                       traffic which can flow over the bridge.

                                 Longfellow Bridge: The construction stage anticipated to have the

                       most adverse effect on traffic would provide one travel lane in the in-

                       bound travel direction and all outbound traffic would be detoured to other

                       routes. The one inbound lane would be diverted to the outbound side of

                       the bridge, and it would terminate at a new signalized intersection in Bos-

                       ton. The new signalized intersection is currently an unsignalized intersec-

                       tion which serves outbound traffic to the bridge and existing traffic from

                       Storrow Drive westbound. Inbound traffic would be permitted to access

                       the Storrow Drive eastbound on-ramp and Charles Street north of Charles

                       Circle.

                                 Cambridge Street (River Street): Throughout the construction pe-

                       riod it is proposed that the existing three lane section be reduced to two

                       lanes. As with other structures in the Basin, traffic flow on this structure is

                       regulated by traffic signals on each end. Intersection capacity would be

                       reduced by the loss of a lane on the bridge. It was assumed that ap-




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                       proximately one-third of the traffic currently using the bridge will choose

                       to find an alternative route to reach their destination.

                               Bowker Interchange – Phase II: The stage of construction which

                       is assumed to create the most severe traffic impacts is Phase 7, during

                       which the Line B Off-ramp and the Storrow Drive eastbound mainline

                       would be under construction simultaneously. During this stage, the lane

                       width of the Line B Off-ramp would be narrowed and the Storrow Drive

                       eastbound mainline would be reduced to one travel lane, reducing the

                       traffic capacity of the mainline lane by approximately 50%.

                               Western Avenue: Throughout the construction period it is pro-

                       posed that the existing three lane section be reduced to two lanes. As

                       with other structures in the Basin, traffic flow on this structure is regu-

                       lated by traffic signals on each end. Intersection capacity would be re-

                       duced by the loss of a lane on the bridge. It was assumed that approxi-

                       mately one-third of the traffic currently using the bridge will choose to find

                       an alternative route to reach their destination.

                               Storrow Drive Tunnels: Extensive traffic modeling was conducted

                       by CTPS for the Storrow Drive Tunnels Reconstruction project. The infor-

                       mation derived for the “Option A” construction period was used by this

                       Study to represent the most serve traffic impact period. During this phase

                       two lanes of traffic would be maintained during peak hours. The east-

                       bound Off-Ramp to Clarendon Street and the on-ramps from Berkeley

                       Street would be closed to accommodate a temporary road for eastbound

                       traffic which would pass through the Berkeley Street tunnel. An east-

                       bound off-ramp to Dartmouth Street would be opened when the Claren-




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                       don Street off-ramp is closed. The westbound off-ramp to Arlington Street

                       would also remain open during peak hours.

                                Memorial Drive over Brookline Street (Reid Overpass): Mainte-

                       nance of eastbound traffic on the overpass is proposed for the duration

                       of construction. When construction activities are taking place on the

                       eastbound lanes, eastbound traffic would be shifted to the westbound

                       lanes. Westbound traffic would be diverted to the Brookline Street sur-

                       face rotary. Temporary traffic signals are proposed at two locations on the

                       north side of the rotary to accommodate the increased traffic demand.

                       When work on the eastbound roadway of the overpass is complete, east-

                       bound traffic will resume travel in the eastbound lanes and the west-

                       bound lanes will be closed. It is assumed that no eastbound vehicles on

                       Memorial Drive will choose to divert during construction activities. It is

                       assumed that 10% of Memorial Drive westbound traffic will choose to

                       divert from the Brookline Street surface rotary to an alternate route.

                                Eliot Bridge: Two 11-foot wide traffic lanes are proposed for the

                       duration of construction activity. This matches the number of lanes cur-

                       rently provided, but the lanes would be slightly narrower than the existing

                       12-foot lanes. It was assumed that 10% of traffic currently using the

                       bridge would choose to use an alternate route to avoid the construction

                       activities.

                                North Harvard Street (Larz Anderson Bridge): Throughout the

                       construction period it is proposed that the existing four lane section be

                       reduced to two lanes (one lane in each direction). As with other structures

                       in the Basin, traffic flow on this structure is regulated by traffic signals on




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                       each end. The ability of the traffic signals to serve vehicles is reduced by

                       the reduction in the number of lanes on the bridge. It was assumed that

                       approximately one-half of the traffic currently using the bridge in each

                       direction will choose to find an alternative route to reach their destina-

                       tion.

                               Memorial Drive (Phase II): It was assumed that construction ac-

                       tivities associated with this project would be primarily confined to reduc-

                       tion of one lane at any time, during which three lanes would be main-

                       tained at any one given time. Since traffic volumes through this area are

                       directional in nature, a reversible lane traffic management strategy would

                       be effective. This strategy would maintain two lanes eastbound and one

                       lane westbound during the morning peak hour, and one eastbound lane

                       and two westbound lanes during the afternoon peak hour. Utilizing this

                       strategy, all traffic in the primary direction could be accommodated, but a

                       small percentage of traffic in the secondary direction would most likely

                       seek an alternative route. It was assumed that 10% of westbound traffic

                       would divert to an alternate route during the morning peak hour and 10%

                       of eastbound traffic would divert to an alternate route during the after-

                       noon peak hour.

                       Alternate Travel Routes & Trip Reassignment
                       The following section will describe the alternate routes for each structure

                       on which diverted trips have been reassigned during Longfellow Bridge

                       Construction. These traffic reassignments supplement the information

                       presented in Volume I of this report, and have only been used when the

                       Longfellow Bridge is under construction. The origin and destination in-




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                       formation used to derive the following routes comes from a select-link

                       analysis performed by the Central Transportation Planning Staff (CTPS).

                       For a description of the select-link analysis please refer to Volume I of this

                       report.

                       Craigie Dam Bridge and Drawbridge
                       The results of the select-link analyses conducted for these structures are

                       presented in Tables M-1 and M-2 located in Appendix M of Volume II. In-

                       bound traffic is generally originating in East Cambridge, Somerville, and

                       areas along Route 28 north of the Craigie structures. A significant per-

                       centage of inbound traffic also originates in the Route 2 corridor and

                       travels along Memorial Drive to Land Boulevard at the O’Brien Highway

                       intersection. Inbound vehicles are generally destined for Downtown Bos-

                       ton, East Boston (including the airport), Back Bay, and areas along I-93

                       south of Boston.

                                 The select-link analyses also indicate that outbound traffic on the

                       Craigie Bridges generally originates along I-93 and Route 3 south of Bos-

                       ton, and in Downtown Boston and East Boston. These trips are generally

                       destined for East Cambridge and Somerville.

                                 Five primary routes have been developed to accommodate the

                       origin-destination trends. The routes are presented in Figure H2, located

                       in Appendix H. The routes divert inbound traffic from Memorial Drive,

                       O’Brien Highway, and Gilmore Bridge to cross the Charles River via the

                       Charlestown Bridge, the Longfellow Bridge, the Harvard Bridge, or the

                       Eliot Bridge. Outbound traffic from Cambridge Street, Storrow Drive, and I-

                       93 would also be diverted to the Charlestown Bridge, the Longfellow




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                       Bridge, the Harvard Bridge, or the Eliot Bridge; in addition these outbound

                       trips would be diverted to the I-93 Sullivan Square Exit. The percentage of

                       diverted traffic expected to use each diversion route is presented in the

                       following table:

                         Craigie Dam Bridge and Drawbridge
                                                       Percentage of Diverted Trips Using Route
                                  Route                       AM                        PM
                                                    Inbound        Outbound   Inbound    Outbound
                         Charlestown Bridge            30%           40%       20%           30%
                         Longfellow Bridge             15%            -        20%            -
                         Mass. Avenue                  10%           30%       10%           25%
                         Eliot Bridge                  15%           10%       10%           15%
                         I-93                          30%           20%       40%           30%



                       Boston University (BU) Bridge
                       The results of the select-link analyses conducted for these structures are

                       presented in Tables M-3 and M-4 located in Appendix M of Volume II. The

                       analysis shows that inbound trips originate in East and Central Cam-

                       bridge, and in the cities along I-93 located north of Boston. Inbound trips

                       are destined for Brookline, Brighton, and areas along the Route 9 corridor

                       located within Route 128. The origin and destination trends for outbound

                       trips are very similar to the inverse of the inbound trips (i.e. inbound ori-

                       gins are outbound destination, etc.).

                                A number of routes have been developed to accommodate the

                       origin-destination trends, and are presented in Figure H3, located in Ap-

                       pendix H. Generally, trips are expected to divert to the Western Avenue /

                       River Street bridges, Massachusetts Avenue, the Longfellow Bridge, the

                       Craigie Bridges, and to the Masspike and I-93.




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                                The percentage of diverted traffic expected to use each diversion

                       route is presented in the following table:

                         Boston University Bridge
                                                       Percentage of Diverted Trips Using Route
                                  Route                       AM                      PM
                                                    Inbound    Outbound     Inbound        Outbound
                         Larz Anderson Bridge          -            10%         -            10%
                         Western Avenue              25%            N/A       25%            N/A

                         River Street                 N/A           20%        N/A           20%
                         Mass. Avenue                25%            30%       25%            30%
                         Longfellow Bridge           15%             -        15%             -
                         Craigie Dam Bridges         15%            20%       15%            20%
                         I-90                        10%            10%       10%            10%
                         I-90 & Route 128            10%            10%       10%            10%



                       Longfellow Bridge
                       The results of the select-link analyses conducted for this structure is pre-

                       sented in Tables M-5 and M-6 located in Appendix M of Volume II. The

                       analysis shows that inbound trips are primarily originating in Cambridge,

                       Somerville, and the areas along the Route 2 corridor. Inbound trips are

                       generally destined for downtown Boston, Back Bay, and East Boston (in-

                       cluding Logan Airport). Outbound trips are originating in East Boston, and

                       the cities and towns along I-93 and Route 3 south of Boston. Outbound

                       trips are generally destined for Cambridge.

                                Five primary routes have been developed to accommodate the

                       origin-destination trends. The routes are presented in Figure H4, located

                       in Appendix H, and include diversions to the Craigie Bridges, Massachu-

                       setts Avenue, Eliot Bridge, North Harvard Street (Larz Anderson) Bridge,

                       and the Western Avenue / River Street Bridges.




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                               The percentage of reassigned traffic expected to use each diver-

                       sion route is presented in the following table:

                         Longfellow Bridge
                                                       Percentage of Diverted Trips Using Route
                                  Route                       AM                        PM
                                                    Inbound        Outbound   Inbound    Outbound
                         Eliot Bridge                  25%           10%         -           20%
                         Craigie Dam Bridges          50%            40%       40%           30%
                         Mass. Avenue                  25%           30%       40%           30%
                         River Street                  N/A           10%        N/A          10%
                         Western Avenue                 -            N/A       20%           N/A
                         North Harvard Street
                                                        -            10%         -           10%
                         (Larz Anderson)


                       Bowker Interchange - Phase II
                       Information collected through the Storrow Drive Origin-Destination (O-D)

                       Survey was used to asses the origin and destination characteristics of

                       trips using these facilities. The results of the O-D Survey results for the

                       Storrow Drive eastbound mainline and the Bowker Interchange east-

                       bound off-ramp from Storrow Drive are presented in Tables M-19 and M-

                       20 located in Appendix M of Volume II.

                               The O-D survey data show that a significant percentage of the

                       trips using the eastbound off-ramp to the Bowker Interchange are origi-

                       nating in the area along Route 2, and that these trips are destined for the

                       Fenway area of Boston. Trips using Storrow Drive eastbound, east of the

                       Bowker Interchange off-ramps, are originating in the same areas as the

                       Bowker off-ramp, but these trips are primarily destined for the Back Bay,

                       Beacon Hill, and Downtown Boston.

                               A number of routes have been developed to accommodate the

                       origin-destination trends. The routes are presented in Figure H6, located


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                       in Appendix H, and include Memorial Drive, Commonwealth Avenue, the

                       Massachusetts Turnpike, and Beacon Street through Cambridge as diver-

                       sion routes around the Bowker Interchange area. A small percentage is

                       also expected to exit Storrow Drive to Charlesgate East and use the local

                       roadway network below the Bowker Overpass to access Boylston Street or

                       to re-enter Storrow Drive eastbound. The percentage of diverted traffic

                       expected to use each diversion route is presented in the following table:

                         Bowker Interchange – Phase II
                                                         Percentage of Diverted Trips Using Route
                                     Route                          AM                       PM
                                                                         Line “B”              Line “B”
                                                       Mainline                     Mainline
                                                                         on-ramp               on-ramp
                         I-90                            10%               15%       10%         15%
                         BU Bridge                         -              25%          -         25%
                         Mass. Avenue                    20%              30%        20%         30%
                         Longfellow Bridge (inbound)     20%                -        20%          -
                         Craigie Dam Bridges             20%                -        20%          -
                         Charlesgate West                10%              30%        10%         30%
                         Commonwealth Ave.               10%                -        10%          -
                         I-93                            10%                -        10%          -



                       Storrow Drive Tunnels
                       Traffic reassignments generated by CTPS for the Storrow Drive Recon-

                       struction Project have also been used in this project. Traffic volume

                       changes expected during the construction period are presented in Figure

                       H8, located in Appendix H, for the morning and afternoon peak period.

                       These figures show that traffic is expected to increase on the Mass Turn-

                       pike, Memorial Drive, Beacon Street (west of Dartmouth Street), Com-

                       monwealth Avenue, the Bowker westbound on-ramp, and the loop around

                       the Public Gardens (Boylston Street, Charles Street, Beacon Street, and




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                       the Storrow Drive eastbound on-ramp). Traffic using the Longfellow Bridge

                       in the outbound direction has been diverted to the Craigie Dam bridges

                       during Longfellow Bridge Construction. Traffic volume changes in the

                       Charles River Basin are primarily due to the relocation of the Clarendon

                       Street eastbound off-ramp to Dartmouth Street, and the closure of the

                       Storrow Drive eastbound and westbound on-ramps from Berkeley Street.

                       Traffic Analysis Results
                       The following discussion will present the intersection level of service

                       analysis results for each individual synchronization project. Analysis re-

                       sults have been generated using the existing morning and afternoon

                       analysis models. Changes in traffic volumes determined through the trip

                       reassignment process were then made to the base volumes. Intersection

                       changes such as lane and lane width reductions or traffic control changes

                       that may occur during construction activities were also implemented in

                       the models.

                               Traffic reassignments to alternative routes generally increase

                       volumes and degrade traffic operations. In some cases, however, traffic

                       diverted from locations reduces congestion and improves operations at

                       those locations.

                               Complete analysis results are summarized in Tables I1 - I4 and

                       Figures I3, I4, I5, I7 and I9, located in Appendix I. The discussion in this

                       section, however, will focus on intersections which would experience

                       significant reduction in traffic operations (to LOS D, E, or F) as a result of

                       construction activity.




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                       Craigie Dam Bridge and Drawbridge
                       Changes in level of service are generally located in the east end of the

                       Charles River Basin close to the project area.

                       Morning Peak Hour
                       Level of service is expected to degrade significantly at the signalized in-

                       tersection of Longfellow Bridge Inbound and Charles Street (LOS D to LOS

                       E). Level of service at the unsignalized intersections within the study area

                       is not expected to degrade significantly during the morning peak hour.

                       Afternoon Peak Hour
                       The level of service is expected to degrade significantly at the following

                       three signalized intersections during the afternoon peak hour:

                            • Beacon Street at Massachusetts Avenue (LOS D to LOS E)
                            • Cambridge Street and Rutherford Avenue at Maffa Way and Main
                               Street (LOS D to LOS E)
                            • Gilmore Bridge at the Rutherford Avenue southbound ramps
                               (LOS D to LOS E)

                       Degradation in level of service is not expected on the approaches to un-

                       signalized intersections within the study area.

                       Boston University (BU) Bridge
                       A significant percentage of traffic was assumed to divert from the Boston

                       University Bridge during the construction period. The central location of

                       this structure permits a variety of alternate routes. Consequently de-

                       creases in level of service are spread out over most of the study area.

                       Morning Peak Hour
                       Significant degradation of level of service is expected at the following four

                       signalized intersections during the morning peak hour:

                            • Cambridge Street at the Masspike Ramps (LOS D to LOS E)
                            • River Street at Memorial Drive (LOS E to LOS F)


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                            • Beacon Street at Commonwealth Avenue and Brookline Avenue
                               (LOS D to LOS E)
                            • Longfellow Bridge inbound at Charles Street (LOS D to LOSE)

                       Degradation of level of service is not expected on the approaches to un-

                       signalized intersections within the study area.

                       Afternoon Peak Hour
                       During the afternoon peak hour, level of service is expected to degrade

                       significantly at the following five signalized intersections:

                            • Western Avenue at Memorial Drive (LOS E to LOS F)
                            • Cambridge Street at Turnpike Ramps (LOS D to LOS E)
                            • Memorial Drive eastbound ramps at Massachusetts Avenue
                               (LOS C to LOS F)
                            • Beacon Street at Massachusetts Avenue (LOS D to LOS F)
                            • O’Brien Highway at Leverett Circle (LOS E to LOS F)

                       Degradation of level of service is not expected on the approaches to un-

                       signalized intersections within the study area.

                       Longfellow Bridge
                       The inclusion of the inbound travel lane serves to reduce the traffic im-

                       pact caused by construction activities at the Longfellow Bridge.

                       Morning Peak Hour
                       Level of Service is expected to degrade significantly at the signalized in-

                       tersection of Cambridge Street and Soldiers Field Road westbound off-

                       ramp during the morning peak hour.

                               Degradation of level of service is not expected on the approaches

                       to unsignalized intersections within the study area.

                       Afternoon Peak Hour
                       During the afternoon peak hour, level of service is expected to degrade at

                       the following six signalized intersections:


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                            • Cambridge Street at Soldiers Field Road eastbound on-ramp
                               (LOS D to LOS E)
                            • Memorial Drive westbound ramps at Massachusetts Avenue
                               (LOS C to LOS E)
                            • Memorial Drive eastbound ramps at Massachusetts Avenue
                               (LOS C to LOS E)
                            • Beacon Street at Massachusetts Avenue (LOS D to LOS F)
                            • Cambridge Street westbound at Charles Street (LOS C to LOS E)
                            • O’Brien Highway at Leverett Circle (LOS E to LOS F)

                       Degradation of level of service is not expected on the approaches to un-

                       signalized intersections within the study area.

                       Bowker Interchange (Phase II)
                       Significant degradation of level of service would primarily occur in the

                       central area of the Charles River Basin during construction. The traffic

                       analysis results show that this project is more disruptive to traffic during

                       the morning peak hour than during the afternoon peak hour. This trend is

                       due to the fact that both roadways affected by the most severe traffic im-

                       pact stage of construction are inbound roadways and their peak traffic

                       period is the morning peak hour. Therefore, more traffic would be di-

                       verted by this project during the morning peak hour than during the after-

                       noon peak hour.

                       Morning Peak Hour
                       Level of service is expected to degrade significantly at the following four

                       signalized intersections during the morning peak hour:

                            • Western Avenue at Soldiers Field Road eastbound off-ramp
                               (LOS C to LOS F)
                            • Western Avenue at Memorial Drive (LOS D to LOS F)




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                            • Cambridge Street at Soldiers Field Road eastbound on-ramp
                               (LOS C to LOS E)
                            • River Street at Memorial Drive (LOS E to LOS F)
                       Significant degradation of level of service is also expected on the follow-

                       ing approaches to unsignalized intersections within the study area:

                            • Northbound right turn movement from Memorial Drive onto the
                               Longfellow Bridge Inbound (LOS E to LOS F)

                       Afternoon Peak Hour
                       Level of service is expected to degrade significantly at the following two

                       signalized intersections during the afternoon peak hour:

                            • Cambridge Street at Soldiers Field Road eastbound on-ramp
                               (LOS D to LOS F)
                            • Beacon Street at Massachusetts Avenue (LOS D to LOS E)

                       Significant degradation of level of service is not expected on the ap-

                       proaches to unsignalized intersections within the study area:

                       Storrow Drive Tunnels
                       Significant degradation of level of service would not be isolated to one

                       specific area, but would be spread throughout the study area.

                       Morning Peak Hour
                       The level of service is expected to degrade significantly at the following

                       three signalized intersections during the morning peak hour:

                            • Cambridge Street at Turnpike Ramps (LOS D to LOS E)
                            • River Street at Memorial Drive (LOS E to LOS F)
                            • Beacon Street at Arlington Street (LOS C to LOS E)

                       Degradation of level of service is not expected on the approaches to un-

                       signalized intersections within the study area.




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                       Afternoon Peak Hour
                       The level of service is expected to degrade significantly at the following

                       five signalized intersections during the afternoon peak hour:

                            • Boston University Bridge at Brookline Street Rotary (LOS D to
                               LOS F)
                            • Boston University Bridge at Commonwealth Avenue (LOS E to
                               LOS F)
                            • Beacon Street at Massachusetts Avenue (LOS D to LOS E)
                            • Beacon Street at Arlington Street (LOS E to LOS F)
                            • Boylston Street at Arlington Street (LOS D to LOS F)

                       Degradation of level of service is not expected on the approaches to un-

                       signalized intersections within the study area.




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                       Concurrent Project Combinations
                               Thus far, projects have been analyzed on an individual basis to

                       determine the potential effect each project would have on traffic opera-

                       tions within the Charles River Basin study area. The following section will

                       focus on the effect of multiple projects occurring simultaneously.

                               Based upon the DCR’s ABP Schedule (Volume III, Figure D1 in Ap-

                       pendix D), the following combinations of concurrent projects were identi-

                       fied for analysis.

                       Combination 1
                             Bowker Interchange - Ramp H
                             Boston University (BU) Bridge
                       Combination 2
                             Boston University (BU) Bridge
                             Craigie Dam Bridge and Craigie Drawbridge
                       Combination 3
                             Boston University (BU) Bridge
                             Craigie Dam Bridge and Craigie Drawbridge
                             Western Avenue
                             North Harvard Street (Larz Anderson)
                       Combination 4
                             Boston University (BU) Bridge
                             Craigie Dam Bridge and Craigie Drawbridge
                             Western Avenue
                             North Harvard Street (Larz Anderson)
                             Cambridge Street (River Street)
                       Combination 5
                             Boston University (BU) Bridge
                             Western Avenue
                             North Harvard Street (Larz Anderson)
                             Cambridge Street (River Street)
                             Longfellow Bridge


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                       Combination 6
                             Boston University (BU) Bridge
                             North Harvard Street (Larz Anderson)
                             Cambridge Street (River Street)
                             Longfellow Bridge
                       Combination 7
                             North Harvard Street (Larz Anderson)
                             Cambridge Street (River Street)
                             Longfellow Bridge
                       Combination 8
                             Cambridge Street (River Street)
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                       Combination 9
                             Cambridge Street (River Street)
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Memorial Drive over Brookline Street (Reid Overpass)
                       Combination 10
                             Cambridge Street (River Street)
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Memorial Drive over Brookline Street (Reid Overpass)
                             Eliot Bridge
                       Combination 11
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Memorial Drive over Brookline Street (Reid Overpass)
                             Eliot Bridge
                       Combination 12
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Eliot Bridge




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                       Combination 13
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Eliot Bridge
                             Storrow Drive Tunnels
                       Combination 14
                             Longfellow Bridge
                             Bowker Interchange – Phase II
                             Storrow Drive Tunnels
                       Combination 15
                             Bowker Interchange – Phase II
                             Storrow Drive Tunnels
                       Combination Traffic Analysis Methods
                               Traffic volume reassignments for individual projects are the basis

                       for developing traffic volumes for the project combinations. Individual

                       traffic reassignments for each project included in a given combination

                       have been added to the existing traffic volumes to describe traffic condi-

                       tions during that combination.

                               Two time periods have been used to account for background traf-

                       fic growth in the Charles River Basin. The two periods are:

                               Period 1 - 2007 through 2011

                               Period 2 - 2012 through 2017

                               Combinations 1 through 7 occur during Analysis Period 1, and the

                       remaining eight combinations take place during Analysis Period 2. A traf-

                       fic growth rate of 0.5% per year was developed to account for background

                       traffic growth within the Charles River Basin. This growth rate was devel-

                       oped using regional trip tables supplied by CTPS. Only trips starting and

                       ending in the traffic analysis zones within the Charles River Basin study




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                       area were used to calculate the growth rate. Traffic volumes for the

                       combinations occurring in Analysis Period 1 have not been factored be-

                       cause of the likeness to existing conditions. Traffic volumes for combina-

                       tions occurring in Analysis Period 2 have been factored by 0.5% per year

                       compounded annually for 5 years to arrive at the year 2012.

                               The intersection geometry, signal timing and signal phasing used

                       to evaluate existing conditions were used as a starting point to evaluate

                       the project combinations. Where intersections were modified to reflect

                       lane reductions, lane width reductions or traffic control changes in the

                       individual projects these same changes were carried into the combination

                       analysis for each project.

                               The results of the combination analysis are very much influenced

                       by the nuances of the traffic reassignment performed for each individual

                       project. One project could reduce traffic volume at an intersection while

                       another project could increase traffic volume at the same intersection. It

                       is also possible that all of the projects in a combination could increase

                       traffic volumes at an intersection in varying degrees, which makes it diffi-

                       cult at times to determine if a level of service change is attributed to a

                       single project or to the combination of projects. The following flow chart

                       presents a rigorous set of criteria which have been developed to deter-

                       mine if a reduction in intersection level of service is caused primarily by a

                       single project or by the combination of projects.




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                                  Is the LOS for the              NO               Intersection LOS is
                                  Combo = E or F?                                      acceptable.


                                     YES



                                  Are there multiple                                The LOS E or F is
                                     projects that                NO
                                                                                attributed to one project.
                                   increase delay?



                                     YES




                                 Is the difference in
                                 delay between the                                  The LOS E or F is
                                  worst project and                  NO            primarily attributed to
                                      the combo                                        one project.
                                    Significant? *




                                     YES


                               LOS E or F is attributed
                                to the combination of
                                       projects.



                          * A significant difference in delay is approximately 12 seconds, which repre-
                          sents one-half of the range between LOS E and LOS F.




                       Combination Traffic Analysis Results
                               Complete analysis results for each combination are summarized

                       in Figures D6 – D19 and in the tables located in Appendix D.                          The

                       discussion in this section will start with the overall impact of project

                       combinations. The discussion will then turn to the specific intersections




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                       with significant degradation in traffic operations due to the project

                       combinations.

                       Combination 1
                               Project Combination 1 includes two projects: Bowker Interchange

                       - Ramp H, and the Boston University Bridge. The analysis results for the

                       morning and afternoon peak hours are as follows:

                       Morning Peak Hour
                               Level of service would degrade from existing conditions at nine

                       signalized intersections and three unsignalized intersections during the

                       morning peak hour. Of the nine signalized intersections, five would oper-

                       ate at LOS E or LOS F. One of the unsignalized intersections would oper-

                       ate at LOS F and two would operate at LOS E.

                               Comparing the results of the combination analysis to the existing

                       conditions analysis shows that none of the study area intersections would

                       operate at an unacceptable level of service due to the combination of

                       projects.

                       Afternoon Peak Hour
                               Level of service would degrade from existing conditions at nine

                       signalized intersections during the afternoon peak hour, with seven of the

                       nine intersections operating at LOS E or LOS F. None of intersections

                       would operate at LOS E or LOS F because of the combination of projects.

                               The level of service would degrade to LOS E at the unsignalized

                       intersection of Longfellow Bridge outbound and the Storrow Drive west-

                       bound off-ramp, however, the degradation of level of service would not be

                       attributed to the combination of projects.




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                       Combination 2
                               Project Combination 2 includes two projects: the Boston Univer-

                       sity Bridge and the Craigie Dam Bridge and Drawbridge.

                       Morning Peak Hour
                               Level of service would degrade from existing conditions at eight

                       signalized intersections and two unsignalized intersections during the

                       morning peak hour. Of the eight signalized intersections, four would

                       operate at LOS E or LOS F. Both of the unsignalized intersection would

                       operate at LOS F.

                               The analysis results show that only one of the signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects. The intersection of the Longfellow Bridge

                       inbound and Charles Street would operate at LOS F during the morning

                       peak hour primarily due to the increase in traffic from the Craigie Dam

                       Bridges and Boston University Bridge projects.

                               One of the two unsignalized intersections would operate at an

                       unacceptable level of service because of the combination of projects.

                       The Longfellow Bridge inbound at the Memorial Drive ramps would

                       operate at LOS F during the morning peak hour primarily due to the

                       increase in traffic from the Craigie Dam Bridges and Boston University

                       Bridge projects.

                       Afternoon Peak Hour
                               Level of service would degrade at eight signalized intersections

                       during the afternoon peak hour. Seven of the eight intersections would

                       operate at LOS E or LOS F. The following three intersections would oper-




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                       ate at unacceptable levels of service because of the combination of pro-

                       jects:

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Longfellow Bridge inbound at Charles Street (LOS E)

                                The unsignalized intersection of Longfellow Bridge inbound and

                       the Memorial Drive ramps operates at LOS F under existing conditions,

                       and vehicle delay would increase significantly at this intersection due to

                       the combination of the Craigie Dam Bridges and the Boston University

                       Bridge projects.

                       Combination 3
                                Project Combination 3 includes four projects: the Boston Univer-

                       sity Bridge, Craigie Dam Bridge and Drawbridge, Western Avenue Bridge,

                       and the North Harvard Street (Larz Anderson) Bridge.

                       Morning Peak Hour
                                Level of Service would degrade from existing conditions at 11

                       signalized intersections and two unsignalized intersections during the

                       morning peak hour.       Of the 11 signalized intersections, five would

                       operate at LOS E or LOS F. Both of the unsignalized intersections would

                       operate at LOS F.

                                The analysis results show that the following three signalized

                       intersections would operate at an unacceptable level of service due to

                       the combination of projects:

                         • Western Avenue at Soldiers Field Road westbound On-Ramp (LOS E)

                         • Cambridge Street at the Turnpike Ramps (LOS F)




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                         • Longfellow Bridge inbound @ Charles Street (LOS F)

                                The following unsignalized intersection would operate at an

                       unacceptable level of service due to the combination of projects:

                         • Longfellow Bridge inbound at the Memorial Drive ramp (LOS F)

                       Afternoon Peak Hour
                                Level of Service would degrade from existing conditions at ten

                       signalized intersections during the morning peak hour.        Of the ten

                       signalized intersections, eight intersections would operate at LOS E or

                       LOS F.

                                The following three signalized intersections would operate at an

                       unacceptable level of service because of the combination of projects:

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street @ Massachusetts Avenue (LOS F)

                         • Longfellow Bridge inbound at Charles Street (LOS E)

                                The unsignalized intersection of Longfellow Bridge inbound and

                       the Memorial Drive ramps operates at LOS F under existing conditions,

                       and vehicle delay would increase significantly at this intersection due to

                       the combination of the Craigie Dam Bridges and the Boston University

                       Bridge projects.

                       Combination 4
                                Project Combination 4 includes five projects: the Boston Univer-

                       sity Bridge, Craigie Dam Bridge and Drawbridge, Western Avenue Bridge,

                       North Harvard Street (Larz Anderson) Bridge, and the Cambridge Street

                       (River Street) Bridge.




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                       Morning Peak Hour
                               Level of Service would degrade from existing conditions at twelve

                       signalized intersections and two unsignalized intersections during the

                       morning peak hour. Of the twelve signalized intersections, eight would

                       operate at LOS E or LOS F. The unsignalized intersections would operate

                       at LOS F.

                               The analysis results show that the following six signalized

                       intersections would operate at an unacceptable level of service due to

                       the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E)

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS E)

                         • Beacon Street at Massachusetts Avenue (LOS E)

                         • Longfellow Bridge inbound at Charles Street (LOS F)

                               It should be noted that the signalized intersection of Memorial

                       Drive at JFK Street operates at LOS F during existing conditions. Even

                       though this intersection operates at LOS F during existing conditions, the

                       combination of projects significantly affects this intersection because the

                       vehicle delay associated with the combination of projects is expected to

                       be significantly greater than the vehicle delay associated with existing

                       conditions.

                               The unsignalized intersection of the Longfellow Bridge inbound

                       and the Memorial Drive ramp would operate at an unacceptable level of

                       service (LOS F) due to the combination of projects.




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                       Afternoon Peak Hour
                               Level of Service would degrade from existing conditions at ten

                       signalized intersections during the afternoon peak hour.        Of the ten

                       signalized intersections, eight would operate at LOS E or LOS F.

                                The analysis results show that the following five signalized

                       intersections would operate at an unacceptable level of service due to

                       the combination of projects:

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Boylston Street at Massachusetts Avenue (LOS F)

                         • Longfellow Bridge inbound at Charles Street (LOS E)

                               The signalized intersections of River Street at Memorial Drive and

                       Boylston Street at Massachusetts Avenue operate at LOS F under existing

                       conditions. Even though these intersections operate at LOS F during

                       existing conditions, the combination of projects significantly affects these

                       intersections because the vehicle delay associated with the combination

                       of projects is expected to be significantly greater than the vehicle delay

                       associated with existing conditions.

                               The unsignalized intersections of the Longfellow inbound and the

                       Memorial Drive ramp would operate at an unacceptable level of service

                       (LOS F) due to the combination of projects.

                       Combination 5
                               Project Combination 5 includes five projects: the Boston Univer-

                       sity Bridge, Western Avenue Bridge, North Harvard Street (Larz Anderson)




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                       Bridge, the Cambridge Street (River Street) Bridge and the Longfellow

                       Bridge.

                       Morning Peak Hour
                                 Level of Service would degrade from existing conditions at

                       fourteen signalized intersections during the morning peak hour. Of the

                       fourteen signalized intersections, seven would operate at LOS E or LOS F.

                       None of the unsignalized intersections within the study area would have

                       level of service reduction from existing conditions.

                                 The following seven signalized intersections would operate at

                       unacceptable levels of service because of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Cambridge Street at Soldiers Field Road westbound off-ramp (LOS F)

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS E)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at Monsignor O’Brien Highway (LOS F)

                                 None of the unsignalized intersections in the study area would

                       operate at an unacceptable level of service due to the combination of

                       projects.

                                 It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street, O’Brien Highway at Leverett Circle and Land

                       Boulevard at O’Brien Highway are expected to operate at LOS F during

                       existing conditions. Even though these intersections operate at LOS F

                       during existing conditions, the combination of projects significantly




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                       affects these three intersections because the vehicle delay associated

                       with the combination of projects is expected to be significantly greater

                       than the vehicle delay associated with existing conditions.

                       Afternoon Peak Hour
                               Level of Service would degrade from existing conditions at

                       fourteen signalized intersections during the afternoon peak hour. Of the

                       fourteen signalized intersections, seven would operate at LOS E or LOS F.

                               The following ten signalized intersections would operate at an un-

                       acceptable level of service due to the combination of projects:

                         • Western Avenue at Soldiers Field Road westbound On-Ramp (LOS E)

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound On-Ramp (LOS F)

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Boylston Street at Massachusetts Avenue (LOS F)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of River Street

                       and Memorial Drive, Boylston Street and Massachusetts Avenue, and

                       Land Boulevard and O’Brien Highway operate at LOS F during existing

                       conditions. Again, though these intersections operate at LOS F during No-



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                       Build conditions, the combination of projects would significantly affect

                       these three intersections because the vehicle delay associated with the

                       combination of projects is expected to be significantly greater than the

                       vehicle delay associated with existing conditions.

                       Combination 6
                                 Project Combination 6 includes four projects: the Boston Univer-

                       sity Bridge, North Harvard Street (Larz Anderson) Bridge, the Cambridge

                       Street (River Street) Bridge, and the Longfellow Bridge. Traffic operations

                       have not been evaluated for this combination due to the short duration (1

                       month).

                       Combination 7
                                 Project Combination 7 includes three projects: North Harvard

                       Street (Larz Anderson) Bridge, and the Cambridge Street (River Street)

                       Bridge, and the Longfellow Bridge.

                       Morning Peak Hour
                                 Level of Service would degrade from existing conditions at eight

                       signalized intersections during the morning peak hour.       Of the eight

                       signalized intersections, four would operate at LOS E or LOS F. None of

                       the unsignalized intersections within the project study area would have

                       degraded Level of Service during the morning peak hour.

                                 The following two signalized intersections would operate at

                       unacceptable levels of service due to the combination of projects:

                         • Cambridge Street at Soldiers Field Road westbound off-ramp (LOS F)

                         • Memorial Drive eastbound Ramps @ Massachusetts Avenue (LOS F)




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                       Afternoon Peak Hour
                               Level of Service would degrade from existing conditions at twelve

                       signalized intersections during the afternoon peak hour. Of the twelve

                       signalized intersections, eight would operate at LOS E or LOS F. None of

                       the unsignalized intersections within the project study area would have

                       degraded Level of Service during the afternoon peak hour.

                               The analysis results show that the following four signalized

                       intersections would operate at an unacceptable level of service on

                       account of the combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                       Combination 8
                               Project Combination 8 includes three projects: Cambridge Street

                       (River Street) Bridge, the Longfellow Bridge, and Bowker interchange -

                       Phase II.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       sixteen signalized intersections during the morning peak hour. None of

                       the unsignalized intersections with in the study area would have

                       degraded level of service. Of the sixteen signalized intersections, nine

                       would operate at LOS E or LOS F.

                               The analysis results show that the following five signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects:



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                         • Memorial Drive at JFK Street (LOS F)

                         • North Harvard Street at JFK Street and Soldiers Field Road eastbound

                           Ramps (LOS E)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street, O’Brien Highway at Leverett Circle, and Land Boule-

                       vard at O’Brien Highway are expected to operate at LOS F during No-Build

                       conditions. Even though these intersections would operate at LOS F dur-

                       ing No-Build conditions, the combination of projects would significantly

                       affect these three intersections because the vehicle delay associated

                       with the combination of projects is expected to be significantly greater

                       than the vehicle delay associated with No-Build conditions.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       twelve signalized intersections during the afternoon peak hour. Of the

                       twelve signalized intersections, eight would operate at LOS E or LOS F.

                               The following four signalized intersections would operate at an

                       unacceptable level of service because of the combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound On-Ramp (LOS F)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)



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                         • Beacon Street at Massachusetts Avenue (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                       Combination 9
                               Project Combination 9 includes four projects: Cambridge Street

                       (River Street) Bridge, the Longfellow Bridge, Bowker interchange - Phase

                       II, and Memorial Drive over Brookline Street (Reid Overpass).

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       fifteen signalized intersections during the morning peak hour. Of the

                       fifteen signalized intersections, nine would operate at LOS E or LOS F.

                       None of the unsignalized intersections would have level of service

                       reductions during the morning peak hour.

                               The analysis results show that the following six signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • North Harvard Street at JFK Street and Soldiers Field Road eastbound

                           Ramps (LOS E)

                         • Cambridge Street at Soldiers Field Road westbound Off-Ramp (LOS F)

                         • Memorial Drive eastbound Ramps at Massachusetts Avenue (LOS F)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.




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                                 It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street and O’Brien Highway at Leverett Circle are expected to

                       operate at LOS F during No-Build conditions.           Even though these

                       intersections operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect these two intersections

                       because the vehicle delay associated with the combination of projects is

                       expected to be significantly greater than the vehicle delay associated with

                       No-Build condition.

                       Afternoon Peak Hour
                                 Level of Service would degrade from 2012 No-Build conditions at

                       thirteen signalized intersections during the afternoon peak hour, of which

                       eight intersections would operate at LOS E or LOS F.

                                 The following four signalized intersections would operate at

                       unacceptable levels of service due to the combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound On-Ramp (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                                 None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                       Combination 10
                                 Project Combination 10 includes five projects: Cambridge Street

                       (River Street) Bridge, the Longfellow Bridge, Bowker interchange - Phase

                       II, Memorial Drive over Brookline Street (Reid Overpass), and the Eliot

                       Bridge.




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                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       fifteen signalized intersections during the morning peak hour. Of the

                       fifteen signalized intersections, nine would operate at LOS E or LOS F.

                       None of the unsignalized intersections within the study area would have a

                       degraded level of service during this combination of projects.

                               The analysis results show that the following eight signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • North Harvard Street at JFK Street and Soldiers Field Road eastbound

                           Ramps (LOS E)

                         • Cambridge Street at Soldiers Field Road westbound off-ramp (LOS F)

                         • Boston University Bridge outbound at Brookline Street Rotary (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Boylston Street at Massachusetts Avenue (LOS E)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street, O’Brien Highway at Leverett Circle, and Land

                       Boulevard at O’Brien Highway are expected to operate at LOS F during

                       No-Build conditions. Even though these intersections operate at LOS F

                       during No-Build conditions, the combination of projects would



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                       significantly affect these three intersections because the vehicle delay

                       associated with the combination of projects is expected to be significantly

                       greater than the vehicle delay associated with No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       twelve signalized intersections during the afternoon peak hour. Of the

                       twelve signalized intersections, eight would operate at LOS E or LOS F.

                               The analysis results show that the following seven signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Cambridge Street westbound at Charles Street (LOS E)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               As with the morning peak hour, it should be noted that the

                       signalized intersection of River Street at Memorial Drive is expected to

                       operate at LOS F during No-Build conditions.           Even though this

                       intersection would operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect the intersection

                       because the vehicle delay associated with the combination of projects is




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December 2008



                       expected to be significantly greater than the vehicle delay associated with

                       No-Build conditions.

                       Combination 11
                               Project Combination 11 includes four projects: the Longfellow

                       Bridge, Bowker interchange - Phase II, Memorial Drive over Brookline

                       Street (Reid Overpass), and the Eliot Bridge.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       thirteen signalized intersections during the morning peak hour. Of the

                       thirteen signalized intersections, six would operate at LOS E or LOS F.

                               The analysis results show that the following four signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street, O’Brien Highway at Leverett Circle, and Land

                       Boulevard at O’Brien Highway are expected to operate at LOS F during

                       No-Build conditions. Even though these intersections operate at LOS F

                       during No-Build conditions, the combination of projects would

                       significantly affect these two intersections because the vehicle delay




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                       associated with the combination of projects is expected to be significantly

                       greater than the vehicle delay associated with No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       eleven signalized intersections during the afternoon peak hour. Of the

                       eleven signalized intersections, seven would operate at LOS E or LOS F.

                               The analysis results show that the following six signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)

                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS E)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Cambridge Street westbound at Charles Street (LOS E)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                       Combination 12
                               Project Combination 12 includes three projects: the Longfellow

                       Bridge, Bowker interchange - Phase II, and the Eliot Bridge.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       thirteen signalized intersections during the morning peak hour. Of the

                       thirteen signalized intersections, six would operate at LOS E or LOS F.

                       None of the unsignalized intersection within the study area would have

                       reductions in level of service during the morning peak hour.


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                               The following five signalized intersections would operate at an

                       unacceptable level of service because of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • O’Brien Highway at Leverett Circle (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street, O’Brien Highway at Leveret Circle, and Land

                       Boulevard at O’Brien Highway are expected to operate at LOS F during

                       No-Build conditions. Even though these intersections operate at LOS F

                       during No-Build conditions, the combination of projects would

                       significantly affect these two intersections because the vehicle delay

                       associated with the combination of projects is expected to be significantly

                       greater than the vehicle delay associated with No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       eleven signalized intersections during the afternoon peak hour. Of the

                       eleven signalized intersections, seven would operate at LOS E or LOS F.

                               The analysis results show that the following six signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)




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                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS E)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Cambridge Street westbound at Charles Street (LOS E)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                       Combination 13
                               Project Combination 13 includes four projects: the Longfellow

                       Bridge, Bowker interchange - Phase II, the Eliot Bridge, and the Storrow

                       Drive Tunnels.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       fourteen signalized intersections during the morning peak hour. Of the

                       fourteen signalized intersections, seven would operate at LOS E or LOS F.

                       None of the unsignalized intersections within the study area would have a

                       reduction in level of service.

                               The analysis results show that the following six signalized

                       intersections would operate at an unacceptable level of service because

                       of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS E)

                         • Boston University Bridge outbound at Brookline Street Rotary (LOS E)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E)

                         • Land Boulevard at O’Brien Highway (LOS F)




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                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street and Land Boulevard at O’Brien Highway are expected

                       to operate at LOS F during No-Build conditions.       Even though these

                       intersections operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect these two intersections

                       because the vehicle delay associated with the combination of projects is

                       expected to be significantly greater than the vehicle delay associated with

                       No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       sixteen signalized intersections during the afternoon peak hour. Of the

                       sixteen signalized intersections, twelve would operate at LOS E or LOS F.

                               The analysis results show that the following seven signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E)

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Cambridge Street westbound at Charles Street (LOS E)

                         • Land Boulevard at O’Brien Highway (LOS F)




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                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               As with the morning peak hour, it should be noted that the

                       signalized intersection of Land Boulevard at O’Brien Highway is expected

                       to operate at LOS F during No-Build conditions.         Even though this

                       intersection would operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect the intersection

                       because the vehicle delay associated with the combination of projects is

                       expected to be significantly greater than the vehicle delay associated with

                       No-Build conditions.

                       Combination 14
                               Project Combination 14 includes three projects: the Longfellow

                       Bridge, Bowker interchange - Phase II, and the Storrow Drive Tunnels.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       twelve signalized intersections during the morning peak hour. Of the

                       twelve signalized intersections, six would operate at LOS E or LOS F.

                       None of the unsignalized intersections within the study are would have

                       reductions in level of service.

                               The analysis results show that the following three signalized

                       intersections would operate at an unacceptable level of service due to

                       the combination of projects:

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound off-ramp (LOS E)

                         • Land Boulevard at O’Brien Highway (LOS F)




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                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.

                               It should be noted that the signalized intersection of Land

                       Boulevard at O’Brien Highway is expected to operate at LOS F during No-

                       Build conditions. Even though this intersection would operate at LOS F

                       during No-Build conditions, the combination of projects would

                       significantly affect the intersection because the vehicle delay associated

                       with the combination of projects is expected to be significantly greater

                       than the vehicle delay associated with No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       sixteen signalized intersections during the afternoon peak hour. Of the

                       sixteen signalized intersections, twelve would operate at LOS E or LOS F.

                               The analysis results show that the following six signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E)

                         • Western Avenue at Memorial Drive (LOS F)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F)

                         • Beacon Street at Massachusetts Avenue (LOS F)

                         • Cambridge Street westbound at Charles Street (LOS E)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               None of the unsignalized intersections would operate at an

                       unacceptable level of service due to the combination of projects.




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                               As with the morning peak hour, it should be noted that the

                       signalized intersection of Land Boulevard at O’Brien Highway is expected

                       to operate at LOS F during No-Build conditions.         Even though this

                       intersection would operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect the intersection

                       because the vehicle delay associated with the combination of projects is

                       expected to be significantly greater than the vehicle delay associated with

                       No-Build conditions.

                       Combination 15
                               Project Combination 15 includes two projects: Bowker inter-

                       change - Phase II, and the Storrow Drive Tunnels.

                       Morning Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       seven signalized intersections and three unsignalized intersections

                       during the morning peak hour. Of the seven signalized intersections, five

                       would operate at LOS E or LOS F. Approaches at two of the unsignalized

                       intersections would operate at LOS E and an approach at the third

                       intersection would operate at LOS F.

                               The following five signalized intersections would operate at an

                       unacceptable level of service because of the combination of projects:

                         • Memorial Drive at JFK Street (LOS F)

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS F)

                         • River Street at Memorial Drive (LOS F)

                         • Land Boulevard at O’Brien Highway (LOS F)

                               The intersection of the Longfellow Bridge inbound at the

                       Memorial Drive Ramps is the only unsignalized intersection that would


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                       operate at an unacceptable level of service due to the combination of

                       projects during the morning peak hour.

                               It should be noted that the signalized intersections of Memorial

                       Drive at JFK Street and Land Boulevard at O’Brien Highway are expected

                       to operate at LOS F during No-Build conditions.       Even though these

                       intersections operate at LOS F during No-Build conditions, the

                       combination of projects would significantly affect these two intersections

                       because the vehicle delay associated with the combination of projects is

                       expected to be significantly greater than the vehicle delay associated with

                       No-Build condition.

                       Afternoon Peak Hour
                               Level of Service would degrade from 2012 No-Build conditions at

                       ten signalized intersections during the afternoon peak hour. Of the ten

                       signalized intersections, eight would operate at LOS E or LOS F.

                               The analysis results show that the following two signalized

                       intersections would operate at unacceptable levels of service due to the

                       combination of projects:

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E)

                         • Beacon Street at Massachusetts Avenue (LOS E)

                               The unsignalized intersection of Longfellow Bridge inbound and

                       the Memorial Drive Ramps operates at LOS F under existing conditions,

                       and vehicle delay would increase significantly at this intersection due to

                       the combination of the Bowker Interchange - Phase II and the Storrow

                       Drive Tunnels projects.




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                       Mitigation Measures
                               The following section will discuss various mitigation measures

                       that could be applied to intersections which would operate at an unac-

                       ceptable level of service due to a project combination.

                       Signalized Intersection Improvements
                               The first mitigation measure explored for signalized intersections

                       was signal timing changes that would optimize intersection level of ser-

                       vice.

                               Along with signal timing changes, lane use changes were investi-

                       gated to improve intersection operations. An existing roadway approach

                       with two lanes may have a shared left turn and through lane and a

                       shared right turn and through lane. If a large increase in left turn traffic is

                       expected, it may be necessary to change the lane use of the shared left

                       turn and through lane to an exclusive left turn lane. This change would

                       provide the left turning vehicles with queuing space and it would also re-

                       move through vehicles from the left turn queue.

                               Traffic volumes, signal timing, and lane use changes may also re-

                       quire new signal phasing. A low volume left turn movement under exist-

                       ing conditions may operate as a permitted movement (e.g., against op-

                       posing through traffic). If the volume of opposing through vehicles is

                       greatly increased, the left turn movement may need to operate as a pro-

                       tected left turn to allow vehicles an opportunity to turn.

                               Most intersections with in the study area which would have unac-

                       ceptable operations because of the project combinations are located in

                       fully developed areas or are located in recreation areas. For these rea-




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                       sons adding lanes to the intersection approaches was investigated but

                       often it was not considered a practical mitigation measure.

                       Unsignalized Intersection Improvements
                                Fewer options are typically available to mitigate project effects at

                       unsignalized intersections. The mitigation measure investigated first by

                       this project was installation of traffic signal equipment.

                       Mitigation Analysis
                                The following section presents the results of the Combination

                       Analysis with mitigation measures in place.

                       Combination 1
                                No intersections would be effected by the combination of projects

                       in combination 1, and no mitigation measures would be required under

                       Combination 1.

                       Combination 2
                                Signal timing changes are proposed at one intersection during the

                       morning peak hour and at three intersections during the afternoon peak

                       hour. Installation of traffic signals was examined at one unsignalized in-

                       tersection.

                       Signalized Intersections
                                Signal timing changes were analyzed at the intersection of Long-

                       fellow Bridge inbound and Charles Street. Signal operations could be im-

                       proved from LOS F to LOS D during the morning peak hour. The intersec-

                       tion of Cambridge Street westbound and Charles Street should also be

                       retimed because it is a closely spaced signalized intersection operating in

                       coordination with the Longfellow Bridge inbound roadway at Charles

                       Street intersection.




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                                Signal operations could be improved through signal timing

                       changes during the afternoon peak hour at the following three intersec-

                       tions:

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                         • Beacon Street at Massachusetts Avenue (LOS F to LOS E)

                         • Longfellow Bridge inbound at Charles Street (LOS E to LOS D)

                                Though vehicle delay would be reduced at the intersection of

                       Beacon Street and Massachusetts Avenue the intersection would con-

                       tinue to operate at an unacceptable level of service (LOS E) with mitiga-

                       tion measures in place.

                                It should be noted that the intersections of the Memorial Drive

                         ramps with Massachusetts Avenue operate with one traffic signal con-

                         troller. It is possible that signal timing modifications made to improve

                         level of service at one intersection could reduce level of service at the

                         other. Throughout this project signal timing changes at these intersec-

                         tions were monitored to ensure that the intersection operating at an

                         acceptable level of service prior to the implementation of mitigation

                         measures remained at LOS D or better.

                       Unsignalized Intersections
                                Traffic operations at the unsignalized intersection of the Long-

                       fellow Bridge inbound and the Memorial Drive ramps could be improved

                       during both peak hours with the installation of traffic signal equipment.

                       Level of Service would improve during the morning peak hour from LOS F

                       to LOS C and from LOS F to LOS D during the afternoon peak hour.




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                       Combination 3
                                Signal timing changes are proposed at three intersections during

                       both the morning peak hour and the afternoon peak hour. Installation of

                       traffic signals was examined at one unsignalized intersection.

                       Signalized Intersections
                                Signal operations could be improved through signal timing

                       changes during the morning peak hour at the following three intersec-

                       tions:

                         • Western Avenue at Soldiers Field Road westbound on-ramp (LOS E to

                           LOS C)

                         • Cambridge Street at the Turnpike ramps (LOS F to LOS D)

                         • Longfellow Bridge inbound at Charles Street (LOS F to LOS D)

                                During the afternoon peak hour, traffic operations could be im-

                       proved at the following three intersections:

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                         • Beacon Street at Massachusetts Avenue (LOS F to LOS E)

                         • Longfellow Bridge inbound at Charles Street (LOS E to LOS D)

                       Unsignalized Intersections
                                Traffic signal installation was examined at the intersection of

                       Longfellow Bridge inbound and the Memorial Drive Ramp. The installa-

                       tion could improve operations from LOS F to LOS C during the morning

                       peak hour and LOS F to LOS D during the afternoon peak hour.

                       Combination 4
                                Signal timing changes are proposed at six intersections during the

                       morning peak hour and at five intersections during the afternoon peak



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                       hour. Installation of traffic signals was examined at one unsignalized in-

                       tersection.

                       Signalized Intersections
                                Operations could be improved to an acceptable level of service

                       with signal timing changes during the morning peak hour at the following

                       four intersections:

                         • Western Avenue at Soldiers Field Road westbound on-ramp (LOS E to

                           LOS C)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E to

                           LOS C)

                         • Beacon Street at Massachusetts Avenue (LOS E to LOS D)

                         • Longfellow Bridge inbound at Charles Street (LOS F to LOS D)

                                Traffic signal improvements were evaluated at the intersection of

                       River Street and Memorial Drive but a reduction in vehicle delay was not

                       achievable.

                                The intersection of Memorial Drive and JFK Street would remain

                       at LOS F with mitigation measures in place, but vehicle delay would be

                       substantially less.

                                During the afternoon peak hour, vehicle delay could be reduced

                       at the following three intersections, but operations would remain at unac-

                       ceptable levels of service:

                         • River Street at Memorial Drive (LOS F)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS E)

                         • Beacon Street at Massachusetts Avenue (LOS F)




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                                Vehicle delay could be reduced at the intersection of Boylston

                       Street and Massachusetts Avenue through signal timing changes, but the

                       level of service would remain at LOS F. The level of service with mitiga-

                       tion would not be considered unacceptable at this location because the

                       vehicle delay with mitigation would be less than the vehicle delay ex-

                       pected in the No-Build condition.

                                Level of service could improve to an acceptable level at the inter-

                       section of the Longfellow Bridge inbound and Charles Street (LOS E to

                       LOS D)

                       Unsignalized Intersections
                                Traffic signal installation was examined at the intersection of

                       Longfellow Bridge inbound and the Memorial Drive Ramp. The installa-

                       tion could improve operations from LOS F to LOS C during the morning

                       peak hour and LOS F to LOS D during the afternoon peak hour.

                       Combination 5
                                Signal timing changes were examined at seven intersections dur-

                       ing the morning peak hour and at ten intersections during the afternoon

                       peak hour.

                       Signalized Intersections
                                Signal timing modifications could improve level of service at the

                       following three intersections during the morning peak hour:

                         • Cambridge Street at Soldiers Field Road westbound off-ramp (LOS F

                           to LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E to

                           LOS C)

                         • Beacon Street at Massachusetts Avenue (LOS E to LOS D)



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                               Mitigation measures examined would not improve intersection

                         operations to acceptable levels at the following four intersections dur-

                         ing the morning peak hour:

                           • Memorial Drive at JFK Street (LOS F, 82 seconds of delay)

                           • River Street at Memorial Drive (LOS F, 143 seconds of delay)

                           • O’Brien Highway at Leverett Circle (LOS F, 111 seconds of delay)

                           • Land Boulevard at O’Brien Highway (LOS F, 161 seconds of delay)

                               Vehicle delay would increase slightly with mitigation at the River

                       Street at Memorial Drive intersection due to the mitigation improvements

                       made at the Cambridge Street at Soldiers Field Road westbound off-

                       ramp.

                               During the afternoon peak hour, operations could be improved to

                       acceptable levels at the following three intersections through signal tim-

                       ing adjustments:

                         • Western Avenue at Soldiers Field Road westbound on-ramp (LOS E to

                           LOS C)

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)

                               Mitigation measures examined would not improve traffic opera-

                       tions to acceptable levels at the following six intersections during the af-

                       ternoon peak hour:

                         • River Street at Memorial Drive (LOS F, 154 seconds of delay)

                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS E,

                           71 seconds of delay)



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                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E,

                           97 seconds of delay)

                         • Beacon Street at Massachusetts Avenue (LOS F, 128 seconds of de-

                           lay)

                         • O’Brien highway at Leverett Circle (LOS F, 204 second of delay)

                         • Land Boulevard at O’Brien Highway (LOS F, 185 seconds of delay)

                                  Mitigation measures would not improve operations to acceptable

                       levels at the intersection of Boylston Street and Massachusetts Avenue,

                       but they would reduce vehicle delay below the vehicle delay expected in

                       the no-build condition.

                       Unsignalized Intersections
                                  The unsignalized intersections within the study area would not be

                       significantly effected by Combination 5 during either peak hour.

                       Combination 6
                                  Traffic operations or mitigation measures have not been evalu-

                       ated for this combination due to the short duration (1 month).

                       Combination 7
                                  Signal timing modifications were examined at two intersections

                       during the morning peak hour and four intersections during the afternoon

                       peak hour.

                       Signalized Intersections
                                  Traffic signal timing changes could improve intersection opera-

                       tions to acceptable levels at the following two intersections during the

                       morning peak hour:

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)



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                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS C)

                                During the afternoon peak hour, signal timing changes could im-

                       prove intersection level of service to acceptable levels at the following

                       three intersections:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                                The mitigation measures examined would improve intersection

                       operations at the intersection of Beacon Street and Massachusetts Ave-

                       nue (LOS F to LOS E), but this level of service would be unacceptable.

                       Unsignalized Intersections
                                The unsignalized intersections within the study area would not be

                       significantly effected by Combination 7 during either peak hour.

                       Combination 8
                                Traffic signal timing modifications were examined at five intersec-

                       tions during the morning peak hour and four intersections during the af-

                       ternoon peak hour.

                       Signalized Intersections
                                The mitigation measures examined would improve intersection

                       operations to acceptable levels at the following two intersections during

                       the morning peak hour:

                         • North Harvard Street and JFK Street at Soldiers Field Road eastbound

                           ramps (LOS E to LOS D)



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                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS C)

                                The mitigation measures examined at the following two intersec-

                       tions would not result in an acceptable level of service, but would improve

                       the level of service over the No-Build conditions:

                         • Memorial Drive at JFK Street (LOS F with 153 seconds of delay to LOS

                           F with 97 seconds of delay)

                         • O’Brien Highway at Leverett Circle (LOS F with 114 seconds of delay

                           to LOS E with 79 seconds of delay)

                                Signal retiming would not improve signal operations to an accept-

                       able level of service at the intersection of Land Boulevard and O’Brien

                       Highway (LOS F, 186 seconds of delay)

                                During the afternoon peak hour, signal operations could be im-

                       proved to an acceptable level of service at the following three intersec-

                       tions:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)

                         • Memorial Drive eastbound ramp at Massachusetts Avenue (LOS F to

                           LOS D)

                                Signal retiming would not improve signal operations to an accept-

                       able level of service at the intersection of Beacon Street and Massachu-

                       setts Avenue (LOS F with 81 seconds of delay) during the afternoon peak

                       hour.




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                       Unsignalized Intersections
                                The unsignalized intersections within the study area would not be

                       significantly effected by Combination 8 during either peak hour.

                       Combination 9
                                Traffic signal timing changes were examined at six intersections

                       during both the morning peak hour and four intersections during the af-

                       ternoon peak hours.

                       Signalized Intersections
                                Level of service could be improved to acceptable levels with sig-

                       nal timing modifications at the following three signalized intersection:

                         • North Harvard Street and JFK Street at Soldiers Field Road eastbound

                           ramps (LOS E to LOS D)

                         • Cambridge Street at Soldiers Field Road westbound off-ramp (LOS F

                           to LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS C)

                                Intersection level of service could not be improved to acceptable

                       levels through the mitigation measures examined, but the vehicle delay

                       could degrade below No-build conditions at the following two locations:

                         • Memorial Drive at JFK Street (LOS F, 97 seconds of delay)

                         • O’Brien Highway at Leverett Circle (LOS E, 79 seconds of delay)

                                Intersection level of service could not be improved to acceptable

                       levels through the mitigation measures examined at the intersection of

                       Land Boulevard and O’Brien Highway (LOS F with 190 seconds of Delay).




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                                During the afternoon peak hour, level of service could be im-

                       proved to acceptable levels through traffic signal timing modifications at

                       the following three intersections:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                                Traffic signal operations could not be improved to an acceptable

                       level of service through the mitigation measures examined at the inter-

                       section of Beacon Street and Massachusetts Avenue (LOS F, 80 seconds

                       of delay).

                       Unsignalized Intersections
                                The unsignalized intersections within the study area would not be

                       significantly effected by Combination 9 during either peak hour.

                       Combination 10
                                Traffic signal timing changes were examined at eight intersections

                       during the morning peak hour and seven intersections during the after-

                       noon peak hour.

                       Signalized Intersections
                                Level of service could be improved to acceptable levels with sig-

                       nal timing modifications at the following three signalized intersection:

                         • Cambridge Street at Soldiers Field Road westbound off-Ramp (LOS F

                           to LOS D)

                         • Boston University Bridge outbound at Brookline Street Rotary (LOS F

                           to LOS D)



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                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                                  Intersection level of service could not be improved to acceptable

                       levels through the mitigation measures examined at the following three

                       locations:

                         • North Harvard Street and JFK Street at the Soldiers Field Road east-

                           bound ramps (LOS E, 60 seconds of delay)

                         • Boylston Street at Massachusetts Avenue (LOS E, 63 seconds of de-

                           lay)

                         • Land Boulevard at O’Brien Highway (LOS F, 190 seconds of delay)

                                  Level of service would remain at unacceptable levels, but the as-

                       sociated vehicle delay could be reduced below No-Build conditions (or to

                       a comparable level) at the following two intersections:

                         • Memorial Drive at JFK Street (LOS F, 107 seconds of delay)

                         • O’Brien Highway at Leverett Circle (LOS E, 79 seconds of delay)

                                  During the afternoon peak hour, level of service could be im-

                       proved to acceptable levels through traffic signal timing modifications at

                       the following three intersections:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at Soldiers Field Road eastbound on-ramp (LOS F to

                           LOS D)

                         • Cambridge Street westbound at Charles Street (LOS E to LOS D)

                                  Level of service could not be improved to acceptable levels

                       through the mitigation measures examined at the following four intersec-

                       tions:



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                         • River Street at Memorial Drive (LOS F, 121 seconds of delay)

                         • Memorial Drive westbound ramps at Massachusetts Avenue (LOS E,

                           58 seconds of delay)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E,

                           60 seconds of delay)

                         • Beacon Street at Massachusetts Avenue (LOS E, 73 seconds of delay)

                       Unsignalized Intersections
                                The unsignalized intersections within the study area would not be

                       significantly effected by Combination 10 during either peak hour.

                       Combination 11
                                Traffic signal timing changes were examined at four intersections

                       during the morning peak hour and six intersections during the afternoon

                       peak hour.

                       Signalized Intersections
                                Level of service could be improved to acceptable levels with sig-

                       nal timing modifications at the intersection of the Memorial Drive east-

                       bound ramps and Massachusetts Avenue (LOS F to LOS C)

                                Intersection level of service could not be improved to acceptable

                       levels through the mitigation measures examined at the intersection of

                       Land Boulevard and O’Brien Highway (LOS F, 190 second of delay).

                                Intersection operations could not be improved to acceptable lev-

                       els through the mitigation measures examined, but vehicle delay could be

                       reduced below no-build conditions at the following two locations:

                         • Memorial Drive at JFK Street (LOS F, 81 seconds of delay)

                         • O’Brien Highway at Leverett Circle (LOS E, 79 seconds of delay)




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                                During the afternoon peak hour, traffic operations could be im-

                       proved to acceptable levels through traffic signal timing modifications at

                       the following five intersections:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at the Soldiers Field Road eastbound on-ramp (LOS

                           F to LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                         • Beacon Street at Massachusetts Avenue (LOS F to LOS D)

                         • Cambridge Street westbound at Charles Street (LOS E to LOS D)

                                Traffic Operations could not be improved to acceptable levels at

                       the intersection of the Memorial Drive westbound ramps and Massachu-

                       setts Avenue (LOS E, 60 seconds of delay).

                       Unsignalized Intersections
                                The unsignalized intersections within the study area would not be

                       significantly effected by Combination 11 during either peak hour.

                       Combination 12
                                Traffic signal timing changes were examined at four intersections

                       during the morning peak hour and six intersections during the afternoon

                       peak hour.

                       Signalized Intersections
                                Level of service could be improved to acceptable levels with sig-

                       nal timing modifications at the intersection of the memorial drive east-

                       bound ramps at Massachusetts Avenue (LOS F to LOS C).




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                               Traffic signal operations would not be improved to an acceptable

                       level of service with signal timing modifications at the intersection of

                       Land Boulevard and O’Brien Highway (LOS F, 190 seconds of delay).

                               Vehicle delay could be reduced below No-Build conditions at the

                       following two intersections, but the operations would remain at an unac-

                       ceptable level of service:

                         • Memorial Drive at JFK Street (LOS F, 81 seconds of delay)

                         • O’Brien Highway at Leverett Circle (LOS E, 79 seconds of delay)

                               During the afternoon peak hour, level of service could be im-

                       proved to acceptable levels through traffic signal timing modifications at

                       the following five intersections:

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at the Soldiers Field Road eastbound on-ramp (LOS

                           F to LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                         • Beacon Street at Massachusetts Avenue (LOS F to LOS D)

                         • Cambridge Street westbound at Charles Street (LOS E to LOS D)

                               Signal operations could not be improved to an acceptable level of

                       service at the intersection of the Memorial Drive westbound ramps and

                       Massachusetts Avenue (LOS E, 57 seconds of delay)

                       Unsignalized Intersections
                               The unsignalized intersections within the study area would not be

                       significantly effected by Combination 12 during either peak hour.




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                       Combination 13
                                Traffic signal timing changes were examined at six intersections

                       during both the morning and afternoon peak hours.

                       Signalized Intersections
                                Traffic operations could be improved to acceptable levels with sig-

                       nal timing modifications at the following three signalized intersection:

                         • Western Avenue at Soldiers Field Road eastbound off-Ramp (LOS F to

                           LOS D)

                         • Boston University Bridge outbound at the Brookline Street Rotary

                           (LOS E to LOS C)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS E to

                           LOS C)

                                Intersection operations could not be improved to an acceptable

                       level of service through the mitigation measures examined at the follow-

                       ing two locations:

                         • Cambridge Street at the Soldiers Field Road eastbound on-ramp (LOS

                           E, 60 seconds of delay)

                         • Land Boulevard at O’Brien Highway (LOS F, 190 seconds of delay)

                                Traffic operations would remain at an unacceptable level of ser-

                       vice at the intersection of Memorial Drive and JFK Street (LOS F, 83 sec-

                       onds of delay), but the vehicle delay would be below the No-Build delay.

                                During the afternoon peak hour, level of service could be im-

                       proved to acceptable levels through traffic signal timing modifications at

                       the following five intersections:




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E to

                           LOS D)

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at the Soldiers Field Road eastbound on-ramp (LOS

                           F to LOS D)

                         • Memorial Drive eastbound ramps at Massachusetts Avenue (LOS F to

                           LOS D)

                         • Cambridge Street westbound at Charles Street (LOS E to LOS D)

                                  Traffic operations could not be improved to acceptable levels

                       through the mitigation measures examined at the following two intersec-

                       tions:

                         • Beacon Street at Massachusetts Avenue (LOS F, 113 seconds of de-

                           lay)

                         • Land Boulevard at O’Brien Highway (LOS F, 192 seconds of delay)

                       Unsignalized Intersections
                                  The unsignalized intersections within the study area would not be

                       significantly effected by Combination 13 during either peak hour.

                       Combination 14
                                  Traffic signal timing changes were examined at three intersec-

                       tions during the morning peak hour and six intersections during the after-

                       noon peak hour.

                       Signalized Intersections
                                  Traffic operations could be improved to an acceptable level with

                       signal timing modifications at the following two signalized intersections:

                         • Western Avenue at Soldiers Field Road eastbound off-Ramp (LOS F to

                           LOS D)


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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                         • Cambridge Street at Soldiers Field Road eastbound on-Ramp (LOS E

                           to LOS D)

                                  Traffic operations could not be improved to an acceptable level

                       through the mitigation measures examined at the intersection of Land

                       Boulevard and O’Brien Highway (LOS F, 190 seconds of delay)

                                  During the afternoon peak hour, Signal operations could be im-

                       proved to an acceptable level of service through traffic signal timing

                       modifications at the following four intersections:

                         • Western Avenue at Soldiers Field Road eastbound off-ramp (LOS E to

                           LOS D)

                         • Western Avenue at Memorial Drive (LOS F to LOS D)

                         • Cambridge Street at the Soldiers Field Road eastbound on-ramp (LOS

                           F to LOS D)

                         • Cambridge Street westbound at Charles Street (LOS E to LOS D)

                                  Traffic operations could not be improved to an acceptable level

                       through the mitigation measures examined at the following two intersec-

                       tions:

                         • Beacon Street at Massachusetts Avenue (LOS F, 101 seconds of de-

                           lay)

                         • Land Boulevard at O’Brien Highway (LOS F, 192 seconds of delay)

                       Unsignalized Intersections
                                  The unsignalized intersections within the study area would not be

                       significantly effected by Combination 14 during either peak hour.




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                       Combination 15
                                Traffic signal timing changes were examined at four intersections

                       during the morning peak hour and two intersections during the afternoon

                       peak hour. Installation of traffic signals was examined at one unsignal-

                       ized intersection.

                       Signalized Intersections
                                Traffic operations could be improved to an acceptable level with

                       signal timing modifications at the intersection of Western Avenue at Sol-

                       diers Field Road eastbound off-ramp (LOS F to LOS D).

                                Traffic operations could not be improved to acceptable levels

                       through the mitigation measures examined at the following two locations:

                         • River Street at Memorial Drive (LOS F, 217 seconds of delay)

                         • Land Boulevard at O’Brien Highway (LOS F, 143 seconds of delay)

                                Intersection operations would not be improved to an acceptable

                       level of service at the intersection of Memorial Drive and JFK Street (LOS

                       F, 83 seconds) , but the vehicle delay could be reduced below the vehicle

                       delay in the No-Build condition (LOS F, 100 seconds of delay).

                                During the afternoon peak hour, signal operations could be im-

                       proved to an acceptable level of service through traffic signal timing

                       modifications at the intersection of Western Avenue and the Soldiers

                       Field Road eastbound off-ramp (LOS E to LOS D).

                                Level of service could not be improved to an acceptable level

                       through the mitigation measures examined at the intersection of Beacon

                       Street and Massachusetts Avenue (LOS E, 65 seconds of delay)




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
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                       Unsignalized Intersections
                               Traffic operations at the unsignalized intersection of the Long-

                       fellow Bridge inbound and the Memorial Drive ramps could be improved

                       during both peak hours with the installation of traffic signal equipment.

                       Level of Service could improve during the morning peak hour from LOS F

                       to LOS C and from LOS F to LOS C during the afternoon peak hour.

                       Mitigation Analysis - Summary
                       The following provides a summary of intersections experiencing unac-

                       ceptable Level of Service (LOS) operations (defined as LOS E or F) as a

                       result of the various project combinations with mitigation.

                         • The DCR Accelerated Bridge Program Schedule results in 39 occur-

                           rences of LOS E or LOS F at 9 intersections within the Charles River

                           Basin.

                         • These 39 occurrences result in a total cumulative duration of LOS E

                           or LOS F of 67 months in the AM peak hour, and 110 months in the

                           PM peak hour over the 8 year construction duration.

                         • Significant delays occur at the Land Boulevard at O’Brien Highway in-

                           tersection during the morning peak hour, and at all four intersections

                           on either side of the Massachusetts Avenue Bridge during the after-

                           noon peak hour.

                         • Overall, Charles River Basin network delays are comparable to the

                           Base Line Schedule.




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
December 2008



                       Study Limitations
                       This Study is intended to be a planning-level tool. The development of this

                       Study is based primarily upon documentation made available to the BETA

                       Team by other Agencies. No independent structural or traffic analyses,

                       reviews, assessments, or field studies were conducted as part of this

                       Study. Field observations did not include in-depth structural inspections,

                       and were performed without the aid of any special equipment, lane

                       closures, police details, or traffic management controls.

                               It was anticipated that the rehabilitation projects would be limited

                       to the existing structures’ footprints, and would not be designed to

                       accommodate additional traffic volumes.

                               It is not the intent of this Study to determine the remaining

                       service life of structures or the extent of rehabilitation necessary to

                       ensure continued public safety.

                               Detailed structural evaluations to determine if a project can be

                       delayed to meet with the suggested sequence depicted in the

                       Synchronization Plan was not included as part of the Study.




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Charles River Basin Infrastructure Study – DCR Accelerated Bridge Program
December 2008



                       Conclusions
                       This review of the DCR ABP schedule provides a planning-level
                       synchronization schedule that minimizes, to the extent possible, traffic
                       delays and congestion while maintaining public safety and convenience
                       for the duration of the identified rehabilitation projects. The DCR ABP
                       schedule provides a roadmap for the rehabilitation of the twelve
                       identified critical transportation assets within the Charles River Basin
                       over the next eight years. Phase II of the Study is anticipated to include a
                       regional analysis of the traffic impacts, as well as a public comment
                       process. The Central Transportation Planning Staff (CTPS) has the ability
                       to analyze the impacts of the proposed traffic re-assignments within the
                       expanded regional transportation network. The results of that analysis
                       can be used to confirm or adjust the Study’s findings. Additionally, input
                       gathered from major stakeholders and the general public can be
                       incorporated into the Study to ensure that it is based upon the most
                       appropriate data.


                       This schedule should be considered a dynamic document that can be
                       periodically   updated    based    upon    the   actual   status,   progress,
                       commencement, and duration of each individual rehabilitation project.
                       Proposed changes to the schedule of one individual project could be
                       reviewed in relation to the overall Basin construction to determine if
                       those changes would result in degradation of traffic operations. Finally,
                       this schedule could also be utilized as an aid in determining the
                       appropriate timing of design consultant procurement and contractor
                       procurement.




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