Granite Street Traffic Calming

Cambridge, Massachusetts
Source: Pedestrian and Bicycle Information Center (PBIC)


Neighborhood residents were concerned about speeding on Granite Street, a neighborhood collector road used by children to access a school and a park.


Granite Street is located in the Cambridgeport neighborhood, and is bordered by the Morse Elementary School, a playground, and baseball fields on the south side, and houses on the north. In 1998, the Morse School was closed for major renovation. In conjunction with the school renovation, the roadway and sidewalk on Granite Street was reconstructed.

In response to neighbors' concerns about speeding on Granite Street and to improve the safety of neighborhood children going to and from school, the City worked with residents to implement a comprehensive traffic calming design during the roadway reconstruction. Funding for the traffic calming measures came from the City.


Several traffic calming measures improved the pedestrian environment in the Granite Street area. Curb extensions were installed at the intersections of Granite and Magazine Street, Granite and Pearl Street (at the main entrance to the school) and at Granite and Rockingham Street (at the entrance to the park). A raised crosswalk was also constructed across Granite Street at Magazine Street, and a raised intersection was built at Granite and Pearl Streets.

The raised devices were intended to provide a strong visual cue to drivers entering the corridor from Magazine Street and Pearl Street to be aware of non-motorized users. Further, vehicles would be slowed, and pedestrians would be provided with a level crossing area.

The raised crosswalk and the raised intersection were constructed with concrete pavers to replicate the look and feel of brick. Pavers are slip-resistant and durable under traffic. Both raised devices used color contrast to increase their effectiveness--the red color of the crosswalk and intersection highlighted the pedestrian area against the black asphalt of the street.

The approach slopes to the raised devices were lined with highly visible, reflective, slip resistant, and long lasting inlay tape. And, both of the raised devices (the raised crosswalk at Magazine Street and the raised intersection at Pearl Street) were combined with curb extensions, giving pedestrians the added benefit of crossing a much narrower street.

The raised devices and curb extensions were part of a comprehensive traffic calming plan for Granite Street. Additional elements of the project were truncated domes, zebra crosswalk markings, and the removal of a traffic signal. All of the various measures were intended to work together to change the nature of the roadway and to reduce vehicle speeds.


As part of the ongoing evaluation of this project, the City conducted before and after speed studies. The speed limit on Granite Street is 30 mi/h. Before the improvements, the 85th percentile speed on Granite Street was 28 mi/h. The 85th percentile speed was reduced to 24 mi/h after the improvements.

On most residential streets in Cambridge, residents do not feel comfortable coexisting with traffic going 30 mi/h. A speed of 25 mi/h feels more comfortable and is safer for residents, pedestrians, motorists and cyclists. Before the improvements were made 39 percent of vehicles were exceeding 25 mi/h. Only 14 percent of vehicles were exceeding 25 mi/h after the improvements.

The goal of traffic calming is to make streets safer for people to bike, walk, and drive, not to shift traffic from one street onto another street. The City conducted volume counts to determine if traffic was inadvertently shifted and found that traffic has not diverted off Granite Street. Granite Street carried 4,470 vehicles per day before the project and 4,440 vehicles per day afterward.

Although no major maintenance problems have occurred, the City continues to monitor the improvements closely, particularly through the winter. Bollards were installed to help the snowplow operators locate the raised crosswalk and raised intersection. The effects of snow removal and other maintenance issues will continue to be monitored.

In April 1999, the City conducted a non-scientific survey to determine residents' perceptions of the completed traffic calming project. Over 70 percent of residents who responded liked the project, while only 10 percent disliked it. More than half of Granite Street residents perceived that the traffic calming treatments had reduced traffic speeds and improved pedestrian safety. Also, 87 percent thought that the project improved the look of the street, and 65 percent approved of the City doing similar projects in other locations.

The City and residents view this project as a success because the goals of reducing speeds and improving safety were met. The project is visually pleasing and is an enhancement to the community. Residents strongly support the traffic calming project and support more projects like this in Cambridge.


Juan P. Avendano
Traffic Calming Project Manager
Community Development Department
City of Cambridge
238 Broadway
Cambridge, MA 02188
Phone: (617) 349-4655

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