In June, two cyclists in Cambridge were killed while riding through intersections. One of them, Kim Staley, was struck and killed by a truck June 7 at the intersection of DeWolfe and Mt. Auburn streets. Her death is a tragedy; how can we prevent future tragedies?
In general, many crashes can be prevented with the help of better traffic infrastructure. Separated bike lanes, for example, can prevent crashes caused by getting hit by a door, and intersections can also be designed in safer ways that protect at-risk road users.
With that in mind, several volunteers from Cambridge Bicycle Safety gathered at this intersection on Friday, June 21 to make observations and determine recommendations for the intersection. Our observations were made between 4:00 PM and 5:30 PM and the weather was sunny and in the 70s. There was additional input by others on the following day. This time-lapsed video clearly shows the signal phasing and traffic movements.
The intersection of Mt. Auburn Street and DeWolfe Street is very dangerous for people biking east on Mt. Auburn Street. Here are our thoughts on the current conditions, as well as recommendations for signal and intersection improvements, which we shared with Cambridge city staff in early July.
Current conditions
This is a dangerous intersection for people biking east on Mt. Auburn Street. The danger arises from several factors:
- A confusing set of traffic signals for people bicycling.
- A very high percentage of right-turning vehicles.
- A tendency for right-turning vehicles to make sharp turns, in many instances running over the nearside curb.
- The fact that this intersection is located just outside of Harvard Square and thus has many visitors traveling through it for the first time who are likely unfamiliar with bike signals (note Kim Staley, the woman killed on June 7, was visiting from Florida and riding a BlueBike).
Signal issues and recommendations
From our observations it became clear that one of the main issues with this signal was that bicyclists proceeding eastward on Mt. Auburn Street (away from Harvard Square) may not be observing, or know to be looking for the bike signal at the intersection, but rather are looking at the traffic signals for vehicles. Bikes in this direction are traveling downhill at speed towards the intersection where they see a confusing set of traffic signals. They see not one but two turn arrows and two straight arrows that are meant for cars, but to a bicyclist they could easily perceive that they are meant for them. To the far right there is a lone bicycle signal. This coupled with a high percentage of motorized vehicles making a right turn onto DeWolfe (39% of vehicles, by our observation) creates multiple conflicts and near misses per hour. These near misses are frightening to observe.
A particular issue is that the bike signal looks just like the right turn signal, and they are placed right next to each other, which is in violation of the MUTCD (which requires at least 3 feet of separation between signals). When comparing this bike signal’s compliance to a similar one at Mass Avenue and Beacon Street in Boston (similar phasing pattern, downhill approach, heavy bicycle and turning traffic), the compliance for bicyclists is much better at Mass. Avenue and Beacon Street. At Mass. Ave. and Beacon Street, the bicycle signal is separated from the right turn signal by a significant distance (see photo below). Additionally the bike signal is highlighted by a reflective backplate, is an 8” signal head as opposed to a standard vehicular 12” one, and has a BIKE SIGNAL sign.
- We recommend that the city make a short-term improvement of changing both green arrows to flashing yellow arrows and adding “Watch for cyclists” signage. Note the city has already deployed a flashing yellow signal at Mass. Ave. and Prospect Street.
- We strongly recommend removing the secondary right turn signal that is placed near the bike signal, and add a large BIKE SIGNAL sign next to the bike signal.
- We recommend that the city make a medium-term improvement of installing a nearside 4” and 8” bike signal with bike signal signage to further improve the visibility of the bike signal, similar to this nearside signal that was installed at the intersection of Garden Street and Concord Avenue.
- We strongly recommend that the signal phasing be modified such that the bike movement on Mt. Auburn Street always runs when the through movement on Mt. Auburn Street is permitted. The phasing would be as follows. Pedestrians crossing DeWolfe, and all through traffic/bicyclists on Mt. Auburn may go, right turns are held. Then, the right turn from Mt. Auburn is permitted, as well as the northbound bicycle movement on DeWolfe and the crosswalk on the east side of the intersection across Mt. Auburn. Finally, all traffic from DeWolfe would be permitted to proceed as well as the west side crosswalk across Mt. Auburn. This would have several advantages: More green time for each movement as there are fewer phases, less bicycle delay on Mt. Auburn Street, and clearer signaling movements. An increase in bicycle compliance can be expected with fewer signal phases. Additionally, the two-stage “Dutch” left turn from Mt. Auburn onto DeWolfe Street for bicyclists would be more efficient, as the secondary movement would be directly after the Mt. Auburn street bicycle phase.
- We also recommend the removal of the “except bikes” sign next to the “no turn on red sign” should accompany these signal phase changes. It is not safe for bicyclists to make a right turn in conjunction with vehicles turning right onto DeWolfe Street (phase 2), or in conjunction with vehicles continuing straight on DeWolfe Street (phase 3). A larger “oversized” No Turn on Red sign should also be considered to emphasize this restriction.
Intersection issues and recommendations
The turning motion of cars, trucks and buses from Mt. Auburn onto DeWolfe Street is obtuse, as there is nothing stopping vehicles from making a rapid turn. We observed many cars hitting the nearside curb – one can clearly see how black the curb and sidewalk are on the southwest corner of the intersection. This is dangerous to both bicyclists and pedestrians. A reduction in this turning movement may have saved Kim Staley’s life on June 7.
Here are our recommendations:
- The city should prioritize the installation of two concrete traffic islands along the bike lane on either end of the west side crosswalk along DeWolfe Street. These traffic islands would provide safe separation between vehicles and bikes while waiting at a red signal at the intersection and more importantly would keep vehicles from turning at an obtuse angle onto DeWolfe Street. Concrete islands like these have been very effective at slowing down turning vehicles on Tremont Street in the South End of Boston. This is an imperative safety measure, because drivers lose sight of bicyclists in their side mirrors if they begin turning too soon.
- During our observations we noticed a number of trucks and buses making the right onto DeWolfe Street. We recommend the placement of a sign at the Mt. Auburn/DeWolfe Street intersection that states that trucks/buses are not permitted on Memorial Drive.
- A long-term goal to maximize safety for all travel modes would be to construct a protected, raised intersection such that right turning and through traveling bicyclists would be protected from right turning vehicles. This would require removal of some parking on DeWolfe Street.
