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Comments on Paul Smith report
John S. Allen, May 2002
MIT is proposing to build an expensive facility which will increase crash rates for bicyclists and pedestrians alike, will be difficult and expensive to maintain, will make bicycle travel more inconvenient and slower, and will expose the Institute to a very serious liability risk. The MIT Department of Facilities hired a consultant, Paul Smith, to defend this action. The consultant produced a report in May, 2002, which does not answer questions which have been raised about the facility.
The spectrum of opinion about sidewalk bikeways
Let me begin with quotes from two prominent figures in the world of bicycling. Andy Clarke generally favors separate bikeways and bike lanes with the goal of encouraging bicycle use; John Forester criticizes their deficiencies and teaches how to ride on ordinary streets. Clarke and Forester nonetheless have the same opinion of sidewalk bikeways:
These statements by Clarke and Forester are supported by accident studies and borne out by experience. Clarke and Forester, different as their opinions on bikeways are, agree about sidewalk bikeways.
Specific comments on Smith's report
In what follows, I have indented Smith's text to differentiate it from my comments.
AICP is the American Institute of City Planners. Mr. Smith's credentials are as a city planner. He is not trained in traffic engineering. He cites only planning literature. He does not once cite the literature of bicycle crash causation and prevention.
In other words, not one single thing about the project has been changed as a result of previous comments.
This is fantasy. In reality, the cycle track and the adjacent walkway will be used indiscriminately by bicyclists, inline skaters and pedestrians. Two-direction pedestrian traffic is very heavy on the Vassar street sidewalks at class break times, and a five-foot or even eight-foot walkway is inadequate to accommodate it without spillover into the adjacent bikeway. The five foot bikeway is inadequate for one bicyclist to overtake another, especially given that slower bicyclists will tend to keep away from the walkway, and faster bicyclists will then overtake by merging onto the walkway. Bicycle-bicycle and bicycle-pedestrian collisions will result, and they are often serious.
The Dutch and Danish practice of accommodating bicycles on sidepaths dates to before the Second World War and reflects the weight of entrenched practice and bureaucratic resistance to change -- particularly strongly because an admission of error would reveal the bureaucracy as having been responsible for avoidable injuries and fatalities. Dutch and Danish practice also is perpetuated by widespread misconceptions about bicycle crash types and causation.
Sidepath installation began without any research basis to establish whether it provided an acceptable level of safety, and has more recently been subjected to withering scrutiny through a number of European and North American research studies. These have conclusively shown that sidepaths are far more hazardous than either on-street bicycle accommodation or paths away from roads. There are no studies that show opposite results.
Choosing Denmark and the Netherlands as examples is very selective as these are the two countries where sidepath facilities are most entrenched. The story is different elsewhere in Europe. Germany, in particular, has moved decidedly away from sidepath treatments, modifying its traffic laws to remove the mandatory use of many sidepaths, and changing design guidelines to favor on-road improvements. Furthermore, and very much to the point here, Dutch and Danish guidelines are unsanctioned and unapproved in the USA.
I have provided on-line access to many European and American sidepath research studies through a Web page which I made known to the project proponents in early March, 2002. Mr. Smith does not attempt to challenge these studies; he simply ignores them. If Mr. Smith can find any studies to refute the ones I have cited, let him produce them.
As the AASHTO Guide is not available on-line, I posted relevant excerpts on the Web page which I made known to the project proponents in early March. I will address specific deviations from AASHTO guidelines as I make my way through Mr. Smith's claims.
Here's Smith's first specific misstatement about AASHTO. Bike lanes to the right of right turn lanes at major street intersections are contrary to specific AASHTO guidelines. Such bike lanes direct motorists and bicyclists alike to operate contrary to the traffic law (MGL Ch. 90 § 14) -- by directing motorists to turn right from the left lane, and bicyclists to go straight or turn left from the right lane.
In his previous sentence, Mr. Smith mentioned two intersections. Now he claims that there is only one. In fact there are two, and there are driveway junctions as well.
Driveway entrances are called "junctions" rather than "intersections" in the technical literature; however, the technical issues with driveways are the same as at intersections. The path crosses the heavily-used driveways at the Building 39 portal and the West Parking Garage, as well as several others.
Mr. Smith describes the on-street treatment as mitigating conflicts at the Main Street and Massachusetts Avenue intersections. He is correct about this. It would have the same benefits at the driveways.
Smith makes this statement without giving any supporting evidence. On safety grounds, this statement is contradicted by conclusive evidence. The Wachtel-Lewiston study, for example, showed that car-bike collision rates are higher on sidewalks than streets for all age groups, in a general bicyclist population..
Smith's statement also fails to account for the particular bicyclist population that uses Vassar Street. The MIT bicyclist population consists almost entirely of healthy young adults of high intelligence riding multi-geared, efficient bicycles. Sidepaths are only suitable for slow travel. Slow travel is typical of a European population riding heavy single-speed and three-speed bicycles. Smith is claiming that MIT students are not smart enough to operate bicycles according to the same rules of the road they use when driving motor vehicles or riding their bicycles elsewhere in Cambridge, but that on the other hand MIT students are smart enough to operate on a facility which is more hazardous and requires greater vigilance than the road.
In other words, bike lane intersections are safer (I agree, and research bears this out), but sidepath intersections are nonetheless preferable at the driveways.
Just what is different about Vassar Street as completely to overturn the results of a dozen safety studies? Mr. Smith doesn't say. Yes, Vassar Street is different in some ways, but Smith has done nothing to demonstrate that these differences make the proposed design preferable.
And also, who are "we"? Mr. Smith is a consultant who is supposed to be speaking independently in his professional capacity. Use of the first person plural does not reflect this professional posture.
This is the least troublesome part of the project, other than that bicycle lanes to the right of right-turn lanes pose the problems discussed earlier. However, use of the sidepaths for two-way travel (see below) will lead to bicyclists' crossing the intersections against traffic. In other projects, the City of Cambridge has recommended bike lanes as helping to get bicyclists off the sidewalks and to discourage wrong-way travel. But here, the City is acceding to MIT's desire to put bicyclists on sidewalks, and will thereby encourage wrong-way travel.
The provision of an additional travel lane for right turns makes for a real improvement.
However, placing the bike lane to the right of the right turn lane is incorrect, and decidedly not consistent with AASHTO guidance. The results are not "just as with a street with only one approach lane." On such a street, drivers who are preparing to turn right merge to the right curb, and others, including bicyclists, who are going through or turning left, either overtake them on the left or wait behind.
A bike lane to the right of a right turn lane directs bicyclists to overtake on the right of right-turning traffic. Motorists must then yield to bicyclists in their right rear blindspot while also looking ahead and to the left for traffic in the intersection. That action is not reliably possible. Several bicyclists have been killed in the past couple of years in the Boston area when they attempted overtaking to the right of right-turning vehicles. Also, there has been a very serious and widely publicized collision (the Gladstone-Spring incident as reported by Paul Schimek, a PhD in planning from MIT) when a bicyclist overtook a car on the right and struck a pedestrian.
Again, the addition of a turn lane makes a real improvement but the placement of the bike lane is incorrect, and inconsistent with the AASHTO Guide and Massachusetts statutes. The bike lanes should either be put to the left of the right turn lane or discontinued before the intersections, so that bicyclists and motorists are directed to merge to the correct positions for their destinations.
This is a "striped sidewalk" as described by Andy Clarke. The AASHTO Guide warns again and again about placing bicycles on sidewalks and sidewalk-like facilities. Some specific citations from the Guide:
Returning to Smith's letter:
Remember this statement, I'll be referring to it below. This statement reveals that Mr. Smith does not know enough about bicycle operation to speak with any authority on the subject. Operating in a bike lane and on a sidepath are very different. In particular, the sidepath requires slow travel because its design and traffic mix do not allow bicyclists to travel at their normal speed.
These dimensions only say how wide a bikeway should be. They have nothing to do with the location of a bikeway, which is the main issue with this project. These dimensions are smaller than the minimum AASHTO dimensions, and the use of the 1.00 mm dimension is misleading.. The 1.00 m is separation between cyclists. The total width occupied by a pair of cyclists riding 1 m apart is about 1.5 m or 5 feet. This includes no shy distance or space for weaving or crash avoidance.
In citing these dimensions, Smith assumes that traffic on the sidepaths will travel in only one direction. As I said before, that is fantasy. It's well-known, and discussed in the AASHTO Guide, that one-way bicycle paths are used in two directions if the designated facility for the opposite direction is at all less convenient. In the present case, the only alternatives to wrong-way travel for reaching the sidepath on the far side of the street are a longer route, or threading between parked cars and climbing up a curb. Bicyclists will therefore use both sidepaths in both directions. This problem has been described in more detail in materials previously presented to the project planners.
Operation on the cycle traffic is different in several ways from operation on the street, but two paragraphs earlier it was the similar to that on the street.
The left shoulder is grass with encroaching tree roots. The right shoulder is the one-foot wide painted stripe (AASHTO calls for two-foot rideable shoulders on both sides). Between them is the five-foot cycle track.
The available width is barely adequate for one-way overtaking, and as I have indicated before, two-way use of the cycle track is inevitable. The AASHTO minimum recommended width for a two-way bicycle path is 8 feet, with a two-foot rideable shoulder on each side. This provides the minimum lateral operating space for cyclists to allow overtaking. 12 feet is recommended. 16 feet are necessary for acceptably safe simultaneous overtaking with two-way traffic (equivalent to a four-lane roadway).
Furthermore, encroachment of pedestrians onto the cycle track and bicyclists onto the walkway will be the rule rather than the exception. This has been demonstrated over and over. To say otherwise is pure fantasy.
That's good, except that the expense of removing the bikeway when it proves undesirable will be greatly increased.
Why isn't it a sidewalk? Because we paint a stripe down the middle of it and say it isn't. Call it what you want, this is a sidewalk bikeway. AASHTO specifically warns that wider sidewalks may be more hazardous because they encourage faster travel.
Furthermore, the widening of the sidewalks/sidepaths will be accomplished by narrowing the street. There will no longer be bicycle/motor vehicle lane sharing width in the street. This change will further encourage bicyclists to ride on the slower, more hazardous sidepaths.
It's about the third time Smith has made the one-way and Danish-and-Dutch arguments. I've already answered them. Sidepaths are not recommended in the United States, haven't been for over twenty years, and for good reason. The Pasanen and Wachtel-Lewiston studies which I cite show that even one-way sidepaths lead to more car-bike collisions than riding on the road, and riding opposite traffic is far more hazardous yet.
Then what MIT must teach: Ride slowly so collisions with pedestrians aren't too serious. The car-bike crash rate for through travel on a sidepath is about 3 times at high at intersections and driveways when traveling with traffic, and 12 times as high when traveling against traffic, so be careful! Be VERY careful of blocked sight lines: doorways hidden behind groups of pedestrians, portals where a car might be coming out of a driveway where you can't see it, etc. etc.
Stop at every driveway and look over your shoulder, and walk across, because there is no other way you can be sure to avoid the motorists turning across your path. They also will have a hard time seeing you, because of the row of trees and the parked cars between you and them. Oh, and by the way, when you go ride in the rest of Cambridge, it's completely different: there you ride in the street and follow the regular traffic laws.
Remember that elsewhere in Cambridge and throughout the region, it's against the law to ride on the sidewalks in some places, and discouraged in most others. And you must sign this waiver form to absolve MIT for any responsibility for possible crashes on the Vassar Street facility. Your medical coverage will take care of immediate medical expenses (though we can't be responsible for long-term care), and tuition is up $100 per term this year to cover medical insurance and liability insurance cost increases. Got it? Good.
Then a stop sign will have to be placed at every driveway. How many bicyclists do you think will put up with stopping at every driveway when they could continue without stopping in the street?
That is nice, but irrelevant to the design of the sidepaths.
Once again I ask: if the junctions with the major intersections are safer with the bicyclists in the street, then why go to all the trouble of creating driveway junctions which are more hazardous, and then go to even more trouble to try to mitigate the problems?
This gets to the crux of the matter. Bicycles are vehicles. They are not pedestrians. Bicyclists travel too fast for motorists to yield to them reliably at pedestrian-type crossings. Bicycles, like all vehicles, can not sidestep out of the way as pedestrians can. That is why the collision rates at sidepath/driveway junctions are so very high.
No, being designed to mitigate this problem. Motorists do not have eyes in the back of their heads; bicyclists will often be traveling faster than the motorists and will approach in the motorists' right rear blindspot. Smith also describes no measures to mitigate the problem of motorists' exiting driveways, where the sight lines between bicyclists and motorists will be blocked by pedestrians, and by portals.
A 1993 German study showed that raised crosswalks reduced the crash rate on sidepaths from five times to only two times that when bicyclists used the roadway. Is that good enough?
Several lightly-used driveways do not make up for the heavily-used ones at the Building 39 portal and West Parking Garage. Once again, and now for driveways rather than intersections: if the treatment at the Stata Center is desirable, why is it not desirable also at the other driveways?
Mid-block crosswalks are desirable but they do not resolve the issue of wrong-way travel on the cycle tracks. I've said it before: in order to use a mid-block crosswalk, a bicyclist must often either travel opposite the desired direction of travel, making a longer trip, or else travel the wrong way.
Mr. Smith neglects to mention that the bicycle lane passes behind a truck loading zone at the Metropolitan Storage Warehouse. Truckers attempting to unload across the barrier-separated bike lanes in New York City in 1980 are one of the issues that led to the lanes' removal after only a few months. Another of the issues was a rash of fatalities due to motor vehicles' turning across the barrier-separated bike lanes, which are operationally similar to cycle tracks.
No transitions would be necessary if bicyclists were routed outside the line of parked cars..
That does answer one of my comments -- if it in fact works. That is, if the soil maintains its special properties throughout the life of the project.
Note the dangling comparison. Improved over what? Smith doesn't say. I'd say, improved over a narrow sidewalk but still far worse worse than for a street. For a surface to be suitable for bicycling in winter, it must be clear of snow and ice. Drainage and drying of the surface occur spontaneously after plowing of a street, because streets are crowned and have drain inlets. The sidepath will have no drain inlets, and it cannot be graded so water runs off longitudinally from all points. Snow that piles up between the sidepath and street, (whether cleared from the street or the sidepath, or both) will form a dam. Snow will melt onto the surface of the sidepath and then will freeze. Heroic measures -- manual excavation of snow from between the trees in the tree strip, and the use of large amounts of melting chemicals (which also damage bicycles and the pavement, and kill trees) would be necessary to keep the sidepaths open in the winter.
Repeated attempts have been made to keep some bicycle paths in the Boston area open in winter, and they have never been successful.
Nonsense. Not exclusive. Shared with pedestrians and inline skaters, and crossed by driveways at intersections which make for more hazardous encounters with motor vehicles than when riding on the street.
Good. Keep it that way, or maybe stripe bike lanes. End of problem. Cheap, simple, no liability risk, no special maintenance needed.
Notice that Smith does not mention any advantage of this treatment. Neither has he done that anywhere in his report. Perhaps he knows enough not to, as there is none. In fact, the project results in a great increase in expense of both construction and maintenance, and a high crash rate. The great majority of car-bike collisions occur at intersections, and intersections (primarily those with driveways, in this project) become far more hazardous. Collisions between bicyclists and pedestrians also become a far more serious hazard.
You ("we") may believe whatever you want. However, a public works project, just like a medical treatment, must reflect scientific evidence rather than unsubstantiated opinion. It is not reasonable or ethical to use MIT students as experimental subjects for a failed treatment option, or to put the Institute in the position of having to pay for both the treatment and the consequences of its failure. The sidepath treatment flies in the face of national standards, is slower, more hazardous, more expensive, and far more difficult to maintain than the alternative, and poses a serious liability risk for the Institute.
A claim that has been made by the project's proponents that it will encourage bicycle use. True enough, this treatment might fool some people into thinking they are safer than they would be with an on-street treatment. A few more people might ride bicycles, but only a few, because parking restrictions make private motor vehicles impractical for trips around the MIT campus in any case. Any increased bicycle use would only be a tradeoff against use of MIT shuttle buses, and walking.
This project amounts to a "Pied Piper of Hamelin" approach to bicycle planning: build it, people will supposedly be foolish enough to use it, and if you rack up a few fatalities and disabling injuries, and a million-dollar lawsuit for the Institute, well, it's all for the greater good of the Utopian vision of a car-free city, right?
No, it isn't. I've been a utility bicyclist for 38 years and a bicycling activist for 25 years. I'm in favor of reducing motor vehicle use in cities too. But I must reject projects that 1) objectively reduce bicyclists' mobility; 2) put bicyclists and others unnecessarily at risk when safer alternatives are available and 3) in any case, do nothing to reduce use of private motor vehicles. The Vassar Streetscape project is one of the worst I have ever encountered on all of those counts.
Summary: what Smith does and not say
Mr. Smith's statements in support of the sidewalk are rife with contradictions, prevarication and outright falsehoods, as I will show.
Mr. Smith has for the most part ignored my previous comments rather than to answer them, and he has in every case ignored the research data I presented, rather than to try to refute it. Smith's report consists mostly of a description of the project. He does not answer, and does not even address, any of the following questions.
John S. Allen VI '75
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