Evaluating the role of speed reduction on the severity of vehicle-pedestrian crashes: a case study in Palermo, Italy

Introduction – This study examined the influence of real-world vehicle speeds on injury outcomes in police-reported vehicle-to-pedestrian crashes in Palermo, Italy. Specifically, the study quantified the relationship between percentile travel speeds and the risk of fatal and serious injuries (FSI) for pedestrians and assessed the potential effects of small reductions in travel speed using counterfactual scenarios. Methods – Pedestrian crash locations from police-reported vehicle-to-pedestrian crashes in Palermo, Italy, were linked with real-world travel speed data obtained from TomTom Move. Percentile travel speeds (15th, 50th, and 85th) were used as proxies for impact speed to estimate FSI risk using established risk functions. A counterfactual analysis was conducted to assess the potential effects of reducing travel speeds by 3 km/h and 5 km/h across the speed distribution on pedestrian injury risk. Results – A strong positive relationship was observed between percentile travel speeds and increased FSI risk, with substantially higher risks at upper percentile speeds. The counterfactual analysis indicated that reductions of 3 km/h and 5 km/h across the speed distribution could meaningfully reduce the risk of fatal and serious pedestrian injuries. Discussion – The findings suggest that even modest reductions in vehicle speed can substantially improve pedestrian safety, particularly in urban environments with high pedestrian activity. These results highlight the potential value of targeted speed management strategies for reducing the severity of vehicle-to-pedestrian crashes.