I am a bicycle commuter so it was with some interest I read the results of a recent study out of the University of Minnesota. You can read a summary of the results of the study here. (Its short and readable).
The study looked at half mile stretches of six types of roadway in the Twin Cities (MN). Three cyclists rode bikes with radar units attached to the handlebars. The radar was fitted to measure the distance between the cyclist and passing motorists. In Minnesota, state law requires that the driver of a automobile cede right to way while passing a cyclist and the driver has to pass with at least 36 inches between the cyclist and the nearest side of the vehicle. At least 400 passing events were recorded for each type of roadway with about 2900 passing events total recorded. Mostly, the results were predictable.
- Using radar to measure passing distance works and could be a law enforcement tool.
- Dedicated lanes and other forms of separation provided the largest average distance between passing cars and the cyclist.
- Encroachments (passing with less than 36 inches) were most frequent on 4 lane roadway with no special facilities. The rate of encroachment was (substantially) lower for roads with protected bike lanes.
- The rate of encroachment was small with at 1.12%. Of course, traffic being what is it, that means a third of a million near misses in Minneapolis, a relatively bike-friendly city, per year.
I was unsurprised to learn that my commute is on the most dangerous type of road. I was also unsurprised to learn of the low rate of encroachment. I am on the same stretch of road with the same motorists day in and day out. I am sure motorists are used to looking for me (even on dark winter mornings) and in fact I know they do because it is a topic that comes up regularly at parent-teacher conferences (I teach).
Here was the surprising part:
- The data in this study indicate that the rate of encroachment was 3.8 times greater for female cyclists than for male.
I do not understand this result. I believe it because it is data and I am a science teacher. But I don't understand it.
Questions for future study certainly include
- How do motorists identify the gender of the cyclist being passed?
- Why is there a gender difference at all in encroachments?
Possibly less important but still worth study
- How does the gender of the driver or the presence of passengers in an automobile influence the rate of encroachment?
For now though, all I can say is….its just one more thing that my wife and my daughter have to worry about that my son and I don’t.