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John S. Allen

Also see photo tour

This bridge, an important connection between Boston and Cambridge, was rebuilt in the 1990s following the collapse of a bridge with a similar pin-and-hanger design in Connecticut. The reconstruction of the Harvard Bridge widened both the roadway and the sidewalks somewhat. Since the reconstruction, there has been a major redesign of the intersection with the Paul Dudley White bicycle path and Memorial Drive ramps at the Cambridge end. I have produced a photo tour showing conditions on and near the bridge before and after the reconstruction, and I strongly recommend viewing it in connection with this page.

Following is a letter I sent concerning the plans for reconstruction of the intersection at the Cambridge end. As you view the photo tour, you might consider to what degree my recommendations are reflected in the design of the intersection at the Cambridge end as it now exists.

September 14, 1994

Mr. O. Robert Simha
Planning Office
77 Massachusetts Avenue
Cambridge, MA 02139

Dear Mr. Simha:

At its July meeting, the Cambridge Bicycle Committee requested and received an update on the design development for changes to the intersection of Massachusetts Avenue and Memorial Drive adjacent to the MIT campus, proposed by M.I.T.

In addition to those that I understand have been raised by city staff and with which I concur, I have the following comments on behalf of the Cambridge Bicycle Committee:

1) Installation of traffic signals will increase safety of bicyclists on the bicycle path crossing the Harvard Bridge. However, the zigzag course imposed on these bicyclists by the proposed pedestrian channelizing rails and crosswalks away from the intersection creates serious bicycle-pedestrian and bicycle-bicycle conflicts and distracts bicyclists from checking for cross traffic in the bridge roadway. Curve radii for the zigzag course are far below AASHTO design minima for bicycle paths, an avoidable problem. Bicyclists should be able to proceed directly, as at present, to reduce conflicts to a minimum.

2) The pedestrian channelizing rails also greatly complicate movements for bicyclists on the bridge sidewalks traveling to and from Cambridge. Bicyclists headed into Cambridge on the east sidewalk will have either to dodge left into the roadway in the narrow crosswalk opening on the bridge, or continue to the crosswalk across the eastbound Memorial Drive lanes and then turn into the stream of turning traffic exiting the bridge. Similarly, bicyclists proceeding toward Boston who wish to use the upstream bridge sidewalk will have to dodge into the narrow crosswalk opening on the bridge, or else turn into the oncoming traffic stream in the eastbound Memorial Drive lanes upstream of the bridge.

Safety requires minimizing bicyclists' sudden, unpredictable changes of course and conflicts with other traffic. My preference would be longitudinal ramps from the sidewalk to the striped bridge shoulders, on the side of the crosswalk away from the intersection: one ramp for Cambridge-bound bicyclists on the downstream side of the bridge, and one for Boston-bound bicyclists on the upstream side.

As there is a ramp to the bicycle path on the Boston side of the river only from the downstream sidewalk of the bridge, some bicyclists will have to travel toward Boston on the downstream sidewalk. They are best accommodated by unobstructed sidewalk openings at the Memorial Drive/Massachusetts Avenue intersection.

3) The proposed pedestrian channelizing rails create sightline obstruction hazards. For example, a motorist turning right from the bridge into Memorial Drive eastbound may not see a pedestrian or bicyclist entering the crosswalk. This is especially a problem with children who are not visible or barely visible above the rails. Locating crosswalks away from the intersection increases these hazards. It is a recognized axiom of bicycle facilities design that it is safest for crosswalks to be as close to the intersection as possible.

4) The design drawing does not show lanes on the Harvard Bridge correctly. There are striped shoulders which serve as de facto bike lanes. Due to the median strip over the Memorial Drive underpass, the travel lanes on the bridge diverge at the Cambridge end, and the shoulders taper away to nothing. The project presents the opportunity to maintain constant shoulder width through to the end of the bridge. This possibility is not addressed in the plans.

5) Proposed reduction from three to two eastbound surface lanes on Memorial Drive widens the unused strip between the travel lanes and the underpass in the median strip. Removing the outside rather than the inside lane would widen the strip of useable parkland next to the river, and would make more room for bicycle and pedestrian facilities.

It is also possible to eliminate part of the existing grass strip between the westbound lanes of Memorial Drive and the underpass, granted that people on the downstream sidewalk headed into Cambridge will still need a few feet past the underpass to gain a clear view of traffic in the westbound lanes before entering the crosswalk. By moving the westbound lanes closer to the underpass, additional sidewalk space could be created on the MIT side of the westbound lanes.

6) The plans do not address proposed changes in Massachusetts Avenue in Cambridge, including the replacement of parking with bicycle lanes.

I thank you for your attention.

Very truly yours,

John S. Allen, MIT '75

Member, Cambridge Bicycle Committee
Member, Board of Directors, Bicycle Coalition of Massachusetts


cc: Ilyas Bhatti, Commissioner, MDC
Bicycle Coalition of Massachusetts
Elizabeth Epstein, Director, Environmental Program
Lauren Preston, Director of Traffic and Parking
Cara Seiderman, Bicycle Coordinator

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