Spatio-Temporal Hotspot Dynamics of Vulnerable and Protected Road Users in Coastal Tunisia

Road traffic crashes (RTCs) pose major public health and economic challenges, particularly in developing regions where protected road users (PRUs) and vulnerable road users (VRUs) may experience different patterns of collision risk. This study examines the spatial and temporal distribution of PRU and VRU collisions using a multi-stage geospatial analytical framework. The analysis uses five years of georeferenced collision data (2018–2022), comprising 4090 PRU and 3600 VRU incidents recorded along 3720 km of coastal roadways. Spatial and spatio-temporal methods, including hotspot analysis, space-time cube Emerging hotspot analysis, temporal heatmaps, and bivariate co-mapping, were applied to identify collision concentrations and their evolution over time. The results identified 144 significant PRU hotspots and 91 significant VRU hotspots, with concentrations particularly evident in the northern governorates. Emerging hotspot analysis further identified areas showing intensifying spatial concentrations of PRU and VRU collisions over the study period. Temporal patterns indicated distinct but partially overlapping collision patterns: PRU collisions were more concentrated during weekday commuting periods, while VRU collisions showed stronger daytime concentrations, with both groups exhibiting notable nighttime and weekend collision patterns. The spatial and temporal overlap between PRU and VRU collision hotspots indicates that some locations and periods experience elevated collision concentrations across different road-user groups. However, these concentrations should not be interpreted as exposure-adjusted measures of collision risk. The findings provide road-safety authorities with evidence to support spatially and temporally targeted investigations and more differentiated safety strategies for PRUs and VRUs, particularly in resource-constrained settings.