For whom the bell tolls: Road safety effects of tolls ouncongested SCUT highways in Portugal^†

We present a difference-in-differences analysis of the road safety effects of introducing tolls on SCUT highways in Portugal, a policy motivated purely by financial considerations, as congestion was never an issue. Using negative binomial count models and a comprehensive dataset on all mainland municipalities covering 2008 to 2014, we find that introducing tolls led to an increase in the total numbers of accidents and road injuries in municipalities where SCUT highways are located. Additionally, we register a change in the composition thereof, with fewer occurrences on highways (including on SCUT highways) and an increase on national and other roads. Finally, we find that most effects pertained to light injuries. No statistically significant effects were identified for fatal or serious injuries. Furthermore, as a result of introducing tolls on SCUT highways, we estimate that around 20% of the toll revenue collected is lost on the costs linked to road accidents. This questions the rationale of introducing such tolls, even from a revenue-raising standpoint.