Effectiveness of speed enforcement through fixed speed cameras: a time series study

Objective To assess the effectiveness of speed cameras in reducing the numbers of crashes and people injured on the arterial roads of Barcelona, and to assess their long-term effectiveness on the beltway. Methods Time series analyses were performed separately for the arterial roads and the beltway. The stretches of arterial roads encompassing 500 m before and after the location of a speed camera were considered the enforced stretches, the remaining stretches of arterial roads being considered the comparison group. The outcome measures were the numbers of crashes and of people injured. Quasi-Poisson regression models were fitted, controlling for time trend, seasonality and implementation of other road safety measures