Cambridge Bicycle Safety Statement on the Proposed Inman Square Intersection Redesign

Since the death of Amanda Phillips while riding her bike in Inman Square in 2016, the city made some immediate changes to the intersection such as banning certain left turns, and has engaged in a long stakeholder process of how to better design the intersection for the safety of all road users. The proposal now before the City Council is not perfect, as CBS explained in its recommendation relative to all four proposals last year, but the city should be commended for reducing conflict points by including protected bicycle facilities throughout the intersection, and proposing some best-in-class transit improvements such as priority queue jumps and the city’s first floating bus stops. Therefore, we strongly support moving forward with the current plan – we cannot wait another two years for a protected intersection in Inman Square!

The existing Inman Square intersection is dangerous by design for all road users. Besides Phillips, the intersection has led to numerous crashes and injuries of people walking, biking and driving. In terms of major squares of Cambridge, it is as bad as Porter Square in overall crashes, and second only to Central Square for bicycle crashes (see figure). Pedestrian crashes also occur due to the long intersection that encourages speeding and the misalignment of crosswalks with desire lines. Historically, a third of all crashes in the intersection resulted in injuries requiring EMS.

Given the high throughput — Inman Square is along one of the busiest biking corridors in the state — raised bicycle lanes provide the best protection, in line with Vision Zero goals of eliminating fatalities and serious injuries on our roads. As laid out in MassDOT’s Complete Streets guide, protected intersections that eliminate mixing zones provide the safest option for bicyclists (Exhibit 4A). Further, in constrained settings like Hampshire Street, raised bike lanes (e.g., sidewalk-level) reduce the necessary buffer with motor vehicle traffic (Sec 3.2), thus allowing sufficient bike lane width and creating as large as possible sidewalk, benefitting pedestrians.

Other users of the intersection will also benefit from redesigning for safety: with substantially reduced crossing distances and shorter signal times, pedestrians will face less delay and increased safety. Bus riders will benefit from the city’s first floating bus stops, which do not require merging with traffic, and a proposed queue jump that allows buses to get ahead of traffic at the leading signal.

There are some important details of the proposal still to be worked out. With raised bike lanes, different paving surfaces should be incorporated to help delineate biking and walking zones as on Vassar St and Western Ave in Cambridge, and on the same corridor in Somerville on Beacon Street. Additional signage alerting people about the separation should be incorporated, including at key conflict areas of pedestrian crossings, as CBS advocated for in pushing the City Council to adopt Policy Order 2018 #120 that calls for signs or paint in areas with a high number of potential conflicts to remind people riding that they must yield to people crossing on foot.


Credit: Cambridge Police Department