Passenger Age and Gender Effects on Adult Driver Fatal Crash Rate

Driver behavior and crash rates vary with the presence of passengers but the details of this relationship are not well understood. The literature generally does not take into account the characteristics of passengers, yet effects on crashes may vary dramatically with passenger age and gender. This study estimated the amount of exposure (driving miles) done by various driver age/gender categories with various combinations of passengers. Statistical imputation techniques were used to derive travel estimates for various pairings using data from the 2001 National Household Travel Survey. Crash frequencies for every pairing were obtained from the Fatality Analysis Reporting System and were used to compute fatal crash rates (per 10 million trip miles). The findings reported here focus on adult (21 and older) drivers. The results show that drivers of a given type (age/gender group) show dramatically different crash rates as a function of passenger type. Some passenger types are associated with fatal crash rates higher than that with no passenger, while other passenger types are associated with lower crash rates. The details of this relationship depend to some degree on driver characteristics. Crash rates for different driver age/gender groups overlap substantially based on the passenger, so that the “best” and “worst” driver groups are passenger-specific. For adult male drivers, female passengers are generally associated with lower crash rates. For male drivers, there is a higher crash rate with a male passenger of a given age than with a female passenger of the same age, even for child passengers.