A communication transmitted from Louis A. DePasquale, City Manager, relative to Awaiting Report Item Number 18-19, regarding Central Square pedestrian signals

CITY OF CAMBRIDGE Traffic, Parking and Transportation 344 Broadway Cambridge, Massachusetts 02139 www.cambridgema.gov/traffic Joseph E. Barr, Director Phone: [phone removed] Stephanie McAuliffe, Assistant Director for Parking Management Fax: [phone removed] Brooke McKenna, Assistant Director for Street Management Page 1 of 4 MEMORANDUM To: Louis A. DePasquale, City Manager From: Joseph E. Barr, Director Date: March 21, 2018 Re: Awaiting Report 18-19 – Central Square Pedestrian Signals This memorandum summarizes the analysis of the intersection of Massachusetts Avenue with Prospect Street and River Street, in response to the request from City Council Policy Order #28, adopted on February 5, 2018 (Awaiting Report 18-19). The order requested that the Traffic, Parking, and Transportation Department (TPT) consider implementing an ALL WALK pedestrian signal, also known as an exclusive pedestrian phase, to address concerns about conflicts between right turning vehicles and pedestrians. We understand that the most significant concerns with vehicle conflicts are between vehicles turning right from River Street northbound to Massachusetts Avenue and pedestrians crossing the east leg of the intersection (from Carl Barron Plaza to the corner where Starbucks Coffee is located). This concern is exacerbated by the volume of trucks making this turn, particularly as this turn is part of a designated truck route. City Traffic Signal Policy TPT follows a standard policy of providing concurrent pedestrian phases with through and right turning vehicle traffic at all locations where conditions permit safe pedestrian/vehicle interactions. Considerations as to when to separate the movements include: • Locations where unusual intersection or crosswalk alignment may result in unexpected conflicts, • Poor sight distance between pedestrians and vehicles, or • High volumes of turning vehicles (typically considered to be greater than 250 vehicles per hour). In addition to the concurrent pedestrian phasing, we typically provide a Leading Pedestrian Interval (LPI) of three to five seconds during which pedestrians are given the walk signal to begin crossing the intersection in advance of the vehicle green. This pedestrian signal policy is considered a best practice for walkability and intersection safety across the country, and is endorsed by the Cambridge Pedestrian Committee and WalkBoston, the regional pedestrian advocacy group.

Page 2 of 4 Exclusive pedestrian phases are typically used at locations with lower volumes of pedestrians where drivers may be less likely to expect a pedestrian in the crosswalk during the green phase. In locations of high pedestrian volumes, our experience shows that pedestrians will disregard the signal indications to cross parallel to vehicular movements if concurrent phasing is not provided, which can result in additional confusion and potentially unsafe conflicts (since drivers have the right-of-way when turning and may not be expecting pedestrians). Pedestrians waiting for an exclusive pedestrian phase experience considerably higher delay than in a concurrent system, as the walk signals display DON’T WALK indications in all directions for the majority of the signal cycle. The full traffic signal policy is available online: http://www.cambridgema.gov/~/media/Files/Traffic/official-Signal-Policy.pdf Existing Conditions The intersection of Massachusetts Avenue, Prospect Street, and River Street provides crosswalks on all four legs of the intersection. The northbound, eastbound, and westbound approaches each provide a through travel lane and a right turn lane for vehicles, while the southbound approach provides a single shared through/right-turn lane. Bike lanes are provided on Massachusetts Avenue in both directions. Left turns are prohibited on all four approaches in order to minimize both vehicle-to-pedestrian and vehicle- to-vehicle conflicts. The signal provides a 5-second LPI for both pedestrian phases. Pedestrians cross River Street and Prospect Street concurrently with the Massachusetts Avenue through and right turning traffic. Pedestrians cross Massachusetts Avenue concurrently with the Prospect Street and River Street through and right turning traffic. The signal provides a 90-second cycle during the peak hours. TPT staff conducted field observations during both the morning and evening peak periods in order to observe behavior of pedestrians, bicyclists, and drivers and assess opportunities for improvements. During our field visits, we noted that drivers turning right always yielded to pedestrians in the crosswalk. During a typical signal phase, right turning drivers generally need to wait at least 15 to 20 seconds to allow the initial group of pedestrians to clear the crosswalk. At times when Red Line trains had recently arrived, pedestrian volumes are higher and vehicles may need to wait longer prior to finding a gap in pedestrian volumes. Turning Volumes Right turning traffic volumes on all four legs of the intersection are less than 250 vehicles per hour. The eastbound, westbound, and southbound right turning volumes are all below 100 vehicles per hour during the peak periods, while the northbound right turning volume is between 160 and 180 vehicles per hour during the peak periods. Intersection counts indicate that between 1,800 and 2,000 pedestrians per hour utilize the crosswalks. The east leg crosswalk is the busiest with 650 pedestrians per hour during the evening peak period. Travel Delay During the peak periods, drivers experience an average delay of 25 seconds per vehicle during the morning peak hour and 31 seconds per vehicle during the afternoon peak hour due to the traffic signal. Pedestrians experience an average delay of 16 seconds to cross a single leg, while pedestrians crossing two legs experience an average delay of 11 seconds. Vehicle queues do not typically extend beyond the adjacent signalized intersections on Prospect Street at Bishop Allen Drive or on River Street at Green Street except when downstream congestion from other intersections causes traffic to have to stop on green lights.

Page 3 of 4 Crash Data We obtained crash reports for the intersection for the period including 2015 through 2017 in order to assess any existing pedestrian crash patterns. Crash data indicate that there were only two pedestrian- involved crashes during that time period, one involving a pedestrian crossing River Street who was struck by a turning vehicle and one involving a pedestrian crossing the west leg of Massachusetts Avenue who was struck by a turning vehicle. Alternative Pedestrian Phasing Options Our staff analyzed two options to increase separation between pedestrians and turning vehicles; an exclusive pedestrian phase (the ALL WALK phase discussed in the Policy Order) and a Super LPI that involves a significantly lengthened Leading Pedestrian Interval. Exclusive Pedestrian Phase Implementation of an exclusive pedestrian phase would reduce the total amount of time for both vehicle phases and the total amount of time for pedestrians to access the intersection. Under this scenario, the signal would provide a 10-second WALK phase, 18-second FLASHING DON’T WALK clearance phase, and a two-second ALL RED phase. The remaining 60 seconds of the 90 second cycle would be divided up between the Massachusetts Avenue and Prospect Street vehicle phases. We did not consider extending the overall length of the cycle because our signal policy requires signal cycles of less than 90 seconds unless there is no other feasible alternative. Under this scenario, pedestrian delay would be an average of 25 seconds per person, an increase of 56 percent for pedestrians crossing a single leg and 127 percent for pedestrians crossing two legs. Average vehicle delay would be nearly tripled over the existing condition to 68 seconds during the morning peak hour and 106 seconds during the evening peak hour. Vehicle queues would increase on all approaches, with northbound queues extending through the adjacent signalized intersection of River Street and Green Street, potentially compromising safety and operations at that already-complex intersection. We expect that with this configuration, many pedestrians frustrated with the additional delay will disregard the DON’T WALK signal indications and continue to cross the road concurrently with through vehicle traffic. This is particularly likely given the high volume of pedestrians going to and from the Red Line station, particularly those rushing to make a train or a bus connection. Low compliance with the signals can cause unexpected conflicts as drivers assume pedestrians should not enter the intersection during the DON’T WALK phase, while pedestrians continue to expect drivers to yield. Super LPI TPT staff developed another alternative to increase separation for pedestrians while maintaining the current pedestrian phasing scheme which we are calling a “Super LPI.” This would involve separating the right turn vehicle movements from the through for the first portion of the cycle. Each phase would start with a 15-second lead phase during which through vehicles and concurrent pedestrian movements are able to start moving. During this phase, right turning drivers would see a red right arrow indication coupled with the existing NO TURN ON RED signs. The 15-second initial phase allows the first wave of pedestrians to get most of the way across the intersection without any vehicle conflicts. The right turn signal indication would then transition to a flashing yellow right turn arrow, indicating to drivers that they may turn but they are required to yield before completing the turn. This Super LPI operation provides greater protection for pedestrians while retaining the concurrent phasing that minimizes delay for pedestrians. A similar approach has been employed in other locations, including New York City, Montreal, and Charlotte.

Page 4 of 4 This unique signal phasing scheme is only possible for approaches that provide separate through and right turn lanes in order to allow through vehicles to pass by stopped right turning vehicles. As such, this phasing could be implemented on the northbound, eastbound, and westbound approaches. The southbound approach would not be changed under this scenario, however the right turning volume from Prospect Street onto Massachusetts Avenue is very low at less than 50 vehicles per hour. Under this scenario, overall vehicle delay would decrease by 10 to 15 percent for through vehicles, as they will be able to start moving five seconds earlier on each phase compared to existing conditions (since through vehicles would no longer have to wait for the LPI prior to moving). Pedestrian delay would be unchanged, and pedestrian conflicts would be reduced. Conclusions Based on the analysis between the two alternatives and the existing conditions, the Traffic, Parking, and Transportation Department plans to implement the Super LPI signal phasing, which provides increased separation between pedestrians and turning vehicles while maintaining the current favorably low delay for pedestrians. The flashing yellow arrow indications will reinforce that drivers are required to yield to pedestrians in the crosswalk. It is also important to note that the Department of Public Works will soon be beginning the design process for the reconstruction of River Street, which will extend up to this intersection. Should the change we are proposing not fully address the current concerns at this location, the River Street project will provide another opportunity to look at this situation and determine whether additional improvements are needed.