[the following document was distributed at the
Cambridge Bicycle Committee meeting of June 12, 2002]
Why and how the Vassar Street project
needs to be modified
John S. Allen, June 12, 2002
Every research work that has examined bicycle sidewalks of the type
planned for Vassar Street, and compared these with other treatments, has found these
sidewalks among the most dangerous cycling facilities ever constructed. This research
spans 25 years, two continents, and many countries. See research reports linked at http://www.bikexprt.com/bikepol/facil/sidepath/index.htm.
The proposed paths cross the heavily-used West Parking Garage and
Building 39 driveways, where motorists will not expect to confront cyclists riding on the
sidewalks. The paths will also increase conflicts and collisions with pedestrians, who
will cross over and walk on the designated bicycle area of the sidewalk.
The American Association of State Highway and Transportation Officials
(AASHTO) Guide to Bicycle Facilities, the US reference on bikeway design [Print version; CD-ROM version], specifically, repeatedly and strongly counsels
against sidewalk-type facilities and has done so in every edition since 1981.
Such facilities also pose serious maintenance and operational problems,
and are expensive to construct.
Bike lane placement to the right of right-turn lanes and a truck loading
zone also deviate from AASHTO standards.
For all of these reasons, and because the project is being funded and approved
by M.I.T., it also poses a serious liability risk to M.I.T.
What should be done?
An on-street facility would reduce construction and maintenance costs, as well as
liability exposure. It is my understanding that M.I.T. has guaranteed to keep the
sidepaths clear of snow and ice throughout the winters. I can not imagine that this
standard of maintenance is possible without very considerable ongoing expense. I am also
concerned about the need to use chemicals which could damage trees and other vegetation.
The landscaping aspects of the project are very attractive. The elimination of angle
parking and the slowing of motor traffic by raised crosswalks could make the Vassar Street
roadway far more attractive and safer for bicyclists than it has been, as long as the
roadway is not excessively narrowed. I propose that the project be modified so the
sidewalks are designated only for pedestrian use, while the roadway remains wide enough to
allow motorists to overtake bicyclists without crossing the centerline. The potential
exists to have a far better and safer pedestrian walkway if it is not shared with
bicyclists; at the same time, bicyclists will be able to travel faster, in greater safety,
year-round, on the roadway. An education and enforcement effort completes the picture.
For more information about these comments, please view the web pages at http://www.bikexprt.com/vassarst/ . [note:pages now moved to
and Bicycle Transportation, by John Forester (MIT Press) for a discussion of bicycle crash
types and causes, and why bicycle sidewalks are so dangerous.
About the author
John S. Allen is a founding member of the Cambridge Bicycle Committee and the
Massachusetts Bicycle Advisory Board; active MIT alumnus; member of the MIT Bicycle
Committee, 1991 - 1992; President, Boston Area Bicycle Coalition (now MassBike), 1989 -
1992; League of American Bicyclists certified bicycling instructor; author of several
bicycling publications, including Bicycling
Street Smarts, adopted by the states of Pennsylvania and Ohio as their Bicycle
Driver's Manual; and a consultant and expert witness in bicycleaccident cases. His
résumé is at http://www.bikexprt.com/witness/bikeres3.htm
-- Who else says that street cycling is safer than on sidewalks? --
"Adult cyclists are safer on the streets than on
sidewalks; when provided a designated roadway space, bicyclists will have less incentive
to ride on sidewalks, which will be a benefit to pedestrians."
Cara Seiderman, Bicycle/Pedestrian Coordinator, and
Susan Clippinger, Director of Traffic, City of Cambridge,
in the Boston Globe, November 5, 1995.
"In the 1970's...a lot of bad bikepaths were being provided by governments who
didn't know better. Often they were no more than striped sidewalks. Now we do know better
- and AASHTO specifically discourages the provision of sidewalk-type bikepaths. They do
not discourage well-designed trails in their own rights-of-way."
Andy Clarke, with the Bicycle Federation of America,
later with Rails to Trails Conservancy, Association of Bicycle
and Pedestrian Professionals and Federal Highway Administration;
in a letter to Bicycle Retailer and Industry News, 1994.
"In general, the designated use of sidewalks (as a signed shared facility) for
bicycle travel is unsatisfactory ... It is important to recognize that the development of
extremely wide sidewalks does not necessarily add to the safety of sidewalk bicycle
travel, since wide sidewalks encourage higher speed bicycle use and increase potential for
conflicts with motor vehicles at intersections, as well as with pedestrians and fixed
AASHTO, Guide for the Development of Bicycle Facilities, 1999, p. 20.
"Stay out of each of the following bikeway situations: ... bike lanes with berms,
curbs or parked cars between them and the motor traffic lanes, and bike paths alongside
the road like sidewalks. Every one of these situations is more dangerous than riding on
the roadway because:
1. You are trapped in a narrow channel where you cannot maneuver properly to escape
collisions from the cars that cross or turn across it:
2. both you and the motorists are forced to maneuver dangerously into intersections:
3. It is much harder to observe the motorist who may hit you, and much harder for the
motorist to see you.
How you stay away from these situations is immaterial compared to the value of your
John Forester, past President, League of American Bicyclists,
in his book Effective Cycling, published by MIT Press.
"Most important result: Because the separation of different types of traffic by
means of sidepaths behind curbs makes excessive demands on users and leads to crashes,
other solutions are being increasingly recommended for channeling bicycle traffic. Experts
from different backgrounds at the Velo Secur traffic safety conference in Salzburg were
united in the opinion that sidepaths in urban areas are entirely unsatisfactory in many
ways, and should not be used."
German Cycling Federation ADFC: background
on bicycling #173, August 12, 1992, reporting on
Velo Secur conference, Salzburg, Austria, May 2-5, 1990