A doctor from Bath University used a bike fitted with a distance sensor and video camera to record the type of vehicle and the distance at which it passed.
Dr Ian Walker travelled 186 miles around Bristol and Salisbury over a two-month period and was overtaken by 2,500 vehicles during that time. Data gathered showed that white van drivers were, on average, four inches closer to the bicycle than drivers of black cars, chosen for comparison because there was a comparable number with white vans.
Dr Walker said: ‘At the kinds of speeds and distances that cyclists are overtaken on our city streets, reducing the gap between cyclist and vehicle can have life-threatening safety implications.
‘Why white van drivers overtake closer is not clear; it could be a range of things, from social or personality factors, to the length and width of the vans, or even the stereotypical machismo of white van man.
‘Being able to measure the passing distances that different vehicle drivers give to cyclists and other vulnerable road users is the first step in identifying some of the issues that put them most at risk.’