New report asks: are speed camera effects on collisions real or illusory?
Speed cameras in the Thames Valley have had no impact on cutting injury collisions, according to a report that uses a new method to isolate the impact of cameras from other effects. But the area’s former road safety manager says the research is flawed.
Over the last 20 years speed cameras have become a familiar part of the roadside furniture in the UK. But what effect have they had on injury collisions? Assessments have been complicated by the need to isolate the effects of the cameras from wider trends in collisions and the statistical phenomenon of ‘regression to the mean’ (RTM).
RTM relates to the fact that sites with high numbers of collisions in one time period would be expected to have fewer...