Investigating factors affecting injury severities of drivers with low route familiarity level in mountainous highways single-vehicle crashes under different lighting conditions

Mountainous highway single-vehicle crashes present higher fatality rate and are associated with relative poor lighting condition and driver’s route familiarity. This study examined three-year mountainous highway single-vehicle crashes to identify factors influencing injury severities of low route familiarity (LRF) drivers. Random-effects generalized ordered probit (REGOP) models were employed across daylight, dark and dark-lighted conditions. The impact of tunnel and driver’s failure to use a seatbelt on more severe injuries is particularly pronounced under daylight condition, while their effect diminishes under dark conditions. Dark and dark-lighted conditions amplify the risks associated with intersection and driver aged 65 years or older. Sharp turns are difficult for the LRF drivers to figure out, even under daylight condition. Adverse weather condition increases the probability of LRF drivers’ minor injuries under daylight condition, but decreases the probability of LRF drivers’ minor injuries under dark-lighted condition. Driver under alcohol influence increases the probability of LRF drivers’ major injuries by 16.7% under dark condition. These findings can help develop targeted countermeasures and proper policies for LRF drivers and alleviate their injury severities in single-vehicle crashes.