According to a new study from Imperial College London the number of road traffic collisions falls by 30% in areas that feature speed cameras.
The study is the first of its kind in road traffic accident analysis to use a particular type of statistical analysis that takes extra variables into consideration, other than the basic factors of whether an accident happened in a particular location.
The findings come from the Department of Civil Engineering at ICL. A team of scientists from the department took data from 771 camera sites across England, from Sussex and Dorset all the way up to Lancashire and Greater Manchester, alongside a control sample of 4,787 points randomly sampled across the same areas.
The method employed by the team led by Proessor Dan Graham was called a Bayesian doubly-robust estimation method, which they say offers "a promising approach for evaluation of transport safety interventions."
The Bayesian method allowed the team to consider not only measure the statistical likelihood of an accident happening in the areas that happened to have cameras, but whether the fact that speed cameras were present had an impact in the accident happening or not.
The paper concludes that the model the team used could be used more generally to estimate crash factors and their distributions, to better understand how our roads work.
“Our case study results indicate the speed cameras do cause a significant reduction in road traffic accidents, by as much as 30% on average for treated sites," the paper reads.
“This is an important result that could help inform public policy debates on appropriate measures to reduce RTAs.
“The adoption of evidence based approaches by public authorities, based on clear principles of causal inference, could vastly improve their ability to evaluate different courses of action and better understand the consequences of intervention.”