Background To perform a cost–benefit analysis of the installation of speed cameras on the beltways of Barcelona.

Methods The analysis was performed from the society perspective over a 2-year period using a controlled before-and-after study design. The net benefit was calculated using, as benefits, the willingness to pay for the estimated number of people who avoided injury as a consequence of the intervention, subtracting costs and savings. Sensitivity analyses were performed using the maximum and minimum estimated number of people who avoided injury, assuming that there was a minimum of one death avoided, using the maximum value of a statistical life, assigning all implementation costs to the first year and assuming there was no time lost due to speed reduction.

Results Base case results showed a net benefit of €6.8 million. Sensitivity analyses suggested that net benefits could range from €5.6 to €23.1 million over 2 years.

Conclusions The use of speed cameras in urban areas has a favourable economic impact even when assessed using conservative assumptions.