Senior safety zones protect older adults from traffic crashes

South Korea is facing an unprecedented demographic shift, with the world’s lowest fertility rate of 0.75 in 2024 and projections indicating that over 40% of the population will be aged 65 or older by 2050. In response to growing concerns over older pedestrian safety, this study evaluates the effectiveness of senior safety zones, known as Silver Zones, which are pedestrian-focused safety interventions aimed at reducing crashes involving older adults in Seoul. To assess the intervention’s causal impact, we employ Bayesian structural time series models to construct counterfactual crash trends. The model incorporates control groups, such as general zones without intervention, to estimate the intervention’s net effect. A total of 195 Silver Zones were evaluated, integrating spatial indicators such as land use, resident population, and floating population to account for contextual heterogeneity. Results show that 92 out of 195 Silver Zones experienced statistically significant reductions in pedestrian crashes. Overall, pedestrian crashes decreased by 30.3%, with a 25.3% reduction specifically among older pedestrians. A follow-up regression analysis revealed that zones with higher older population shares, denser commercial activity, and greater recreational land use achieved more substantial safety improvements. These findings underscore the importance of tailoring pedestrian safety interventions to the demographic and spatial characteristics of local areas to enhance their effectiveness. • Over 50% of Silver Zones show significant safety effects. • Effective within 300 m and up to 500 m beyond the zone. • Overall, Silver Zones reduced crashes by 30.3%. • Greater effects near parks and community facilities in suburban areas.