In 2006, the EPSRC funded a project to investigate how drivers overtake bicyclists. We modified a bicycle subtly to carry a video system and an accurate ultrasonic distance sensor that could record the proximities of each passing vehicle. I then used this to collect naturalistic behavioural data from over 2200 motorists in real traffic environments in the UK. This was followed by another study which collected an even larger dataset.
There are three key papers arising from this work:
- The first is the original paper containing the findings from my first overtaking study on over 2200 drivers. This 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.. This study examined the effects of road positioning, helmet-wearing and apparent gender on drivers' behaviour.
- The second paper was an additional study, collecting a new set of data. This looked at other factors such as the influence of a rider's outfit on driver behaviour. You can find that at: Walker, I., Garrard, I., Jowitt, F. (2014). The influence of a bicycle commuter's appearance on drivers’ overtaking proximities: An on-road test of bicyclist stereotypes, high-visibility clothing and safety aids in the United Kingdom. Accident Analysis and Prevention, 64, 69-77.
- Most recently, I published a fairly robust response to an attempt to discredit my original study, and you can find that here (full text): Walker, I., Robinson, D.L. (2019). Bicycle helmet wearing is associated with closer overtaking by drivers: A response to Olivier and Walter, 2013. Accident Analysis and Prevention, 123, 107-103. Please read the final paragraph to see why I think debates about helmet efficacy are rather unproductive.
For those wanting to explore the data, here is the complete raw data set (Excel format) from the original 2007 paper. (Word to the wise: you'll probably want to start with a square-root transform on the passing distances before using parametric statistics.)
Finally, a lot of people have contacted me about making their own sensor to do similar reserach. I've published free plans (free as in beer and as in speech) for how to make a cheap Arduino-based device to stick on the back of your bike. Overtaking sensor plans.