Predicting safety performance on motorways during the pandemic based on geometric design: A case study in Portugal

Abstract

The mobility restrictions due to the covid-19 pandemic have created an unprecedented situation in the road system. Declared lockdowns have significantly altered the traffic volumes and perhaps also driver behavior. This study conducts research on crashes occurred on motorway A29 in Portugal before and during the disrupted mobility context. Safety performance functions were adjusted with negative binomial distribution. The segmentation was based on horizontal alignments. 5 of the 27 variables initially considered were found to be significant; namely traffic volume, segment length, curvature change rate, presence of deceleration lane and year. The quality of the fitted models was verified using cumulative residuals plots. The results showed that a traditional statistical modelling approach explains accident occurrence in a similar way before and during the pandemic.