Bicycle overtaking studies

In 2006, the EPSRC funded a project to investigate how drivers overtake bicycliss. Jeff Brewster, from the University of Bath Mechanical Engineering department, modified a bicycle subtly to carry a video system and accurate ultrasonic distance sensor which could record passing proximities.

Professionals (e.g., researchers, authorities, charities, etc.) may download this overview of the main results (PDF, 370k).

The paper containing most of the findings from this study is: Walker, I. (2007). Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Accident Analysis and Prevention, 39, 417-425.

Update, 8 March 2007. For a recent US TV interview, I reanalyzed the data from this experiment to look at the numbers of vehicles coming within 1m (a measure used by the then TRRL back in 1979 in what was, I believe, the very first study of cycle overtaking). Doing this, I found there were 23% more vehicles coming within 1m of the bicycle when a helmet was being worn. I think this is perhaps the clearest way to illustrate the effect of helmet wearing seen in the data.

Two subsidiary analyses were also published on Philica. There is a very slightly tongue-in-cheek (but probably accurate) analysis of white van overtaking and an analysis of time-of-day effects in overtaking behaviour.

Oh, and in the interests of openness, here is the complete raw data set (Excel format) for anyone who wants to check my calculations or do any interesting subsidiary analyses. (Word to the wise: you'll probably want to start with a square-root transform on the passing distances before using parametric statistics.)

Did you come here from the Cyclist View website? Please have a look at this blog post I wrote in response.