Penalty-point system, deterrence and road safety: A quasi-experimental analysis

Abstract We use three complementary quasi-experimental approaches to study the causal effect of introducing a penalty-point system (PPS) in Spain in July 1 2006, on drivers' behavior. According to Regression-Discontinuity (RD) estimates, the PPS decreased the number of traffic offenders by 14%, and this deterrence effect was directly related to the severity of the penalty. Concerns that RD estimates may over- or under-state the longer-run effects of the policy change are addressed by presenting the Difference-in-Differences (DiD) estimates, which reveal that the deterrence effect of this reform increased over time. Crucially, the reform also curbed accidents by 14%, injuries by 16%, and fatalities by 14%, and these effects persisted over time. Difference-in-RD estimates are consistent with the other two approaches. Altogether, the reform represented net benefits of over 946 million EUR per year (or 0.09% of the Spanish GDP) during the first three years after implementation.