Cambridge Civic Journal Forum

In this post, I’m going to examine some of the drawings of its Western Avenue project which the City of Cambridge has provided.

All of the illustrations below are from the City’s conceptual design booklet.

Western Avenue concept drawing

The cars shown parked at the left are real cars, in the original photograph that was modified to show the conceptual design. Typical sedans are about 5 1/2 feet wide, not counting the side-view mirrors, but common light trucks are as much as 6 1/2 feet wide. Big trucks and buses can be 8 1/2 feet wide.

The cars shown parked at the right are drawings added when the photo was modified. All of them are micro-cars, very much smaller than the cars on the left — only about 4 1/2 feet wide.

Bicyclists complain about “door zone” bike lanes — where opening car doors pose a threat. On the other hand, the door zone serves an important function. A motorist can open the car door without its protruding directly into the path of motor traffic, and can walk around the car.

In the drawing below, I have copied the nearest car in the original drawing into each travel lane. This drawing shows too little clearance between parked vehicles and moving ones to allow motorists safely to walk around to the street side of their vehicles or open the doors. The right lane as shown is especially tight, even with micro-cars parked on the right and ordinary sedans in the travel lanes — though Western Avenue is a designated bus and truck route.

Western Avenue concept drawing, modified

To show how wide the left lane is at present, the white line in the foreground replaces the gray patch that is dimly visible in the original drawing, covering up the location of the present lane line.

The parts of the illustration that are from the original photo are to scale — including the cars I have copied into the travel lanes. The drawn-in elements are conceptual, and some are not to scale.

The drawing below, also from the City, is dimensioned, showing a 36-foot wide roadway. The elements are to scale: 10.5 foot travel lanes, 7-foot parking lanes and mid-sized cars 6 feet wide, not counting the mirrors — like a a Ford Taurus. This drawing shows more room between vehicles than the right lane in the photo, but on the other hand, the parked cars are tight against the curbs, and no trucks or buses are shown.

Cross-section of street with cycle track

Now let’s look at an overhead drawing, which shows a typical treatment at an intersection.

Western Avenue at Jay Street

Let’s put more cars and some bicyclists and pedestrians into the picture. I’ve put three bicyclists on the blue strip which represents the cycle track. Two are headed with traffic and one is headed opposite traffic. (Off-street facilities encourage two-direction traffic, and this is particularly so on a one-way street where there is no opposite-direction paired street conveniently nearby.) There also is a group of pedestrians standing on the bulbout before the intersection. Excuse me if the bicyclists and pedestrians look like ants, I’m no Picasso.

Pedestrians and parked cars conceal  right-way bicyclists from drivers of cars A and B, increasing the risk of a “right hook” collision. Also, Car B  is blocking the right-hand travel lane. Such blockages will increase congestion. The more bicyclists, the more often turning motorists will have to wait in the position shown. At present, motorists can keep moving as they prepare to turn right, because they can merge behind a bicyclist before reaching the intersection.

Car C in the drawing must wait far back from the intersection, what with the separate sidewalk and cycle track. Then, on reaching the intersection, as shown in the illustration below, the car must block the cycle track as the driver scans for traffic. If more than one car is in line, both the sidewalk and the cycle track will be blocked at the same time.

Western Avenue at Jay Street, cycle track blocked

Presently, without the cycle track, this kind of blockage happens only for the sidewalk. It is more troublesome and hazardous for bicyclists than pedestrians, because bicyclists are faster, and farther away when the driver must first see them, and can be hidden by buildings or by pedestrians on the sidewalk. The crash rate for wrong-way cyclists on cycle tracks like this one is very high — research in Finland, Sweden and Germany has shown it to be about 10 times as high as for right-way travel on the street. Right-way travel on a cycle track located, like this one, behind parked cars, and with unsignalized intersections and driveways, has been shown only two or three times as hazardous.

There is also a much greater risk of collisons with pedestrians, and with other bicyclists, than when riding in the street. This cycle track has about 6 feet of width where bicyclists are clear of car-door hazards or plantings — very substandard for a two-way facility.

There is a question what the wrong-way bicyclists will do when they reach Franklin Street and the cycle track ends. Most likely, they will go up onto the sidewalk or ride opposite traffic in the bike lane.

Finally, let’s look at the intersection of Western Avenue and Memorial Drive. At present, Western Avenue has four travel lanes approaching the intersection.  The rightmost lane is a right-turn-only lane which the City describes as underutilized. I agree with that description — even in the evening rush hour, I have been able to filter forward to the intersection on my bicycle in that lane.

The City proposes to change that lane into a cycle track, so right turns are made from the next lane to the left. In this connection, I question the City’s conclusion that its plan will not increase congestion. In the evening rush hour, traffic already queues on Putnam Avenue and Memorial Drive, all the way back to River Street. Even one vehicle waiting to turn right, while bicyclists overtake on the right, will block all other vehicles in the lane behind it. This is aside from the issue of institutionalizing the “right hook” — placing all responsibility for bicyclists’ safety on the motorists, and stripping away bicyclists’ defense of merging into the line of right-turning traffic.

Western Avenue at Memorial Drive, conceptual drawing

I suggest instead that bicyclists be encouraged to travel along the left side of the right-turn lane, by means of shared-lane markings and signage, or better, if there is room, a through bike lane.

The question remains of how to handle opposite-direction bicycle traffic. It does not admit of an easy answer.  At this point, I’m most inclined to try to address it on River Street.

And, I’ll add: the sacredness of on-street parking is the issue that makes the problem insoluble. If parking could be removed form one side of Western Avenue, a contraflow bike lane would be an option.

There is no such issue on River Street, because there are many parallel streets in Cambridgeport that allow travel in the opposite direction.

Signing off…