Many times in my career as a traffic engineer and bicycling advocate, I’ve had other professional engineers tell me that they do not support doing something for cyclists that I have proposed either because they are convinced that it is not safe for the majority of cyclists or they do not know how to do it in a way that is safe for cyclists. For example, some years ago I was speaking with the chief traffic engineer for Caltrans District 4 about bicycle access to the Richmond-San Rafael bridge. She told me that she was responsible for the safety of all road users and that she absolutely refused to allow bicyclists to use the ramps necessary to access the bridge. In another case, engineers for the Fort Ord Reuse Agency told me that they did not provide for cyclists on the reconstructed 12th Street interchange to State Route 1 because they did not know how to do it safely. More recently, the chief of the Electrical Systems Branch at Caltrans told me that she did not believe that bicycles could be reliably detected using inductive loops even though I had just given her a detailed presentation showing how it could be done.
I have been asking myself why these professional engineers are so ignorant of bicycle traffic engineering and I now have a theory. In each case, the engineer has placed the burden on proving my assertion on me, but I (and others like me) do not have access to the resources necessary to perform the research to prove our assertions. And those who do have access to those resources are either not asking the right questions or not interested in the answers.
In reviewing research studies on bicycle traffic engineering, the recurring theme that I have found is that the research has not been done or what research has been done is either biased or flawed. Here are three such examples:
A 2005 study for Florida DOT, Sidepath Facility Selection and Design, looked into the characteristics of sidepaths that make them safer than the parallel street. It used a regression model that, when I showed it to my brother (who is a professor of statistical psychology at Kansas State University), turned out to be inadequately documented. My brother recommended that I obtain the raw data for the study. When I asked the contractors who performed the study for the raw data, they said that they had discarded it and to contact FDOT. Inquiries to FDOT revealed that they have a policy against releasing crash data to members of the public. So far, my attempts to obtain the data have been unsuccessful. My brother told me that the standard among researchers in psychology is to keep raw data for 5 years in case of a request from a peer for a review of the data. The policy at the Transportation Research Board (TRB) is for its contractors to keep raw data for 3 years. Without the raw data, there is no way to know whether the research was performed correctly.
A 1999 study performed for the Federal Highway Administration (FHWA), A Comparative Analysis of Bicycle Lanes Versus Wide Curb Lanes, compared conflicts on streets with wide outside lanes vs. similar width streets with bike lanes. But the comparison turned out to be faulty because the streets with wide outside lanes vs. those with bike lanes had unequal levels of traffic as well as different traffic control characteristics and cycling populations. Also, what they called conflicts included ordinary negotiation between cyclists and motorists approaching intersections. Furthermore, several of the researchers’ conclusions were not supported by the data. At the end of the report, the authors baldly state that even though streets with wide outside lanes and streets with bike lanes had similar operating characteristics, bike lanes are preferable because they attract more bicyclists, despite the fact that bicyclist preferences were not in the study’s scope.
A couple of years ago, the chief of the Caltrans Electrical Systems Branch helped write a problem statement, Bicycle Detection and Operational Concept at Signalized Intersections, for research now being done by California Partners for Advanced Transit and Highways (PATH) at UC Berkeley. Inductive loops, however, are not in the scope of the study. Furthermore, the researchers are being asked to develop a procedure to discriminate between bicycles and motor vehicles for the purpose of providing additional minimum green, ignoring the concerns expressed by bicycle advocates for the length of the all-red clearance interval. When asked about these inconsistencies, the principal investigator replied that he was performing the research that Caltrans had requested. It was this comment that led to my presentation to the Caltrans Electrical Systems Branch where the chief told me that she did not believe bicycles could be reliably detected using inductive loops. Of course, she has no research to support her belief, and she has not asked for any because she already knows the answer.
It appears that the social bias against cycling that Bob Mionske describes in his new book, Bicycling and the Law, extends into bicycle traffic engineering research. That is personally disappointing to me, because I was trained as a transportation researcher and I can see when the standards for such research are being violated.
So here is what I think is happening: (1) Professional engineers are trained to base their decisions on data; (2) Bicycle advocates make assertions about bicycle traffic engineering that they believe are true but cannot prove because they do not have the resources to perform the appropriate research; (3) Sponsored research on those assertions either is not done or is done improperly; which (4) Leads professional engineers to make uninformed decisions about bicycle traffic engineering.
I would be interested if anyone has any evidence that will support or refute my theory. In particular, I am interested in any direct evidence that sponsored research into bicycle traffic engineering is either biased or flawed, or is simply not done because the sponsors believe they already know the answers.
Robert M Shanteau, PhD, PE
Consulting Traffic Engineer
13 Primrose Cir
Seaside, CA 93955-4133
Voice: (831) 394-9420
FAX: (831) 394-6045