Sunday, April 18, 2010


Submitted by WILL ALLEN

Since 2003, MIT and the City of Cambridge have narrowed a one miles stretch Vassar Street between Massachusetts Avenue and Memorial Drive to allow for the construction of cycle tracks on both sides of the street. Since Vassar Street is a primary east-west route across the MIT campus for multiple modes of transportation, including vehicles, bicycles, and pedestrians, the goal of the project was to provide safer, more efficient facilities for all of the streets users.
The main features of the project are 5-foot wide cycle tracks along both sides of the roadway. By definition, cycle tracks are typically physically separated from the adjacent roadway, either by vertical grade differences or barrier separation. Narrow cycle tracks typically only allow for one way bicycle traffic; however wide cycle tracks are also common which allow two way cycling.

On Vassar Street, two 5-foot cycle tracks on either side of the street were constructed at sidewalk level. The 5-foot cycle tracks are typically sandwiched between a 5- foot landscaped buffer and a variable width (5-foot minimum) sidewalk. The cycle tracks are surfaced with hot mix asphalt and edged with grey concrete pavers and the sidewalks are constructed of beige concrete pavers.

The intended use, or function, of the reconstructed street is to provide safer travel for vehicles, bicycles, and pedestrians, through separation and allocation of space for each user. The project’s design, or form, includes multiple features aimed at achieving the intended use of the facility. The most important design features are summarized below:
  • The landscape buffer physically separates the edge of roadway from the cycle track, so as to eliminate potential conflicts between vehicles and bicycles.

  • The hot mix asphalt cycle track surface, in contrast to the adjacent sidewalk, is intended to delineate the boundary of the bicycle and pedestrian facilities.

  • “Bicycle only” pavement markings within the cycle track are intended to reinforce to both bicyclists and pedestrians that the cycle track is only for bicycle use and should not be used as a walking path.

  • The cycle track is painted blue in locations where there are potential conflicts between cyclists and other street uses, such as at crosswalks and driveways, where pedestrians or vehicles may want to cross the cycle track.

  • Bulb outs are provided at crosswalks intended to shorten pedestrian and bicycle crossing distances and enhance pedestrian and bicycle visibility.

  • Extra wide curb ramps are provided at crosswalks intended to provide distinguished street crossing zones for different street uses (e.g. bicycles cross at different locations as pedestrians).

  • Improved street lighting (overhead and in-pavement) is intended to better illuminate the roadway and call attention to crosswalks.

  • Terminal locations of the cycle track are clearly identified with signs and colored pavement intended to provide a safe transition between separated vehicle-bicycle traffic and shared on street space.

  • Narrow vehicle lanes, no shoulders, and on street parking suggest cars and trucks should drive slowly along Vassar Street.

  • Single raised crosswalk located on long straight stretch intended to slow vehicles at pedestrian crossing.

When evaluating the actual use of the new facility versus the intended use, there are mixed results, suggesting there could be improvements with the current design. There is no question that many of the design features, such as the landscaped buffer, wider and better illuminated crosswalks, and bulb outs, reduce conflict points between vehicles and pedestrian and bicycles, as intended. Because of this, it would be expected that vehicle-bicycle crashes and vehicle-pedestrian crashes have been significantly reduced as a result of this project.

However, the design intends to also separate pedestrian and bicycle traffic, yet in actuality the design actually falls short of the goal. This design introduces a new conflict between pedestrians and bicyclists which has been well documented since the opening of the project (See here). The primary concern is that the adjacent bicycle and pedestrian facilities, which are not physically separated, allow for bicyclist and pedestrians to travel into the other user’s space. Despite the different surface materials and presence of pavement markings, regular disobedience has been observed which on occasion has lead to crashes or poor levels of service.

One way in which the design might be improved is by providing physical separation between bicyclists and pedestrians. This may be achieved either by grade separation (lowering cycle track 6” to street level) or by barrier separation. One possible barrier separation could include positioning the landscaped buffer between the cycle track and the sidewalk. Another option could provide a row of street lighting or bollards between the cycle track and the sidewalk.

One other improvement would be to construct additional raised crosswalks along Vassar Street so that vehicles cannot reach speeds in excess of 30 mph.

In summary, this project generally achieves its goal of creating a safer street environment through separation of vehicles, bicyclists, and pedestrians; however improvements could be made to further improve safety, particularly between pedestrians and cyclists. While some of the potential improvements may enhance the safety of Vassar Street, perhaps the best low cost solution would be continued and more effective education of the intended use for the street.


  1. I wonder to what extent those bicycle crossings are used as designed.

  2. what a nice street surface I wish that all the cities get rid of the concrete surface and replace it with asphalt

  3. The only way to improve these bicycle sidewalks is to bulldoze them, and restore the original wider roadway. That would provide enough room for standard on-street bike lanes.