Vehicle Occupancy and Crash Risk


This study explores the association between vehicle occupancy and a driver’s risk of causing a fatal crash, not wearing a seatbelt, and using alcohol. The survey population is the set of drivers represented in the Fatal Analysis Reporting System (FARS) (years 1992 to 2002). The independent variables are driver age, driver gender, passenger age, passenger gender, and vehicle occupancy. The outcome variables are whether the driver was at fault in causing the fatal crash, whether the driver wore a seatbelt, and whether the driver had been using alcohol. For male teenager drivers, driving with teenage passengers correlated with an increase risk of causing a crash. For all female drivers, and for male drivers over age 40, passenger presence correlated with a reduced risk of causing a fatal crash. Drivers age 15 to 30 were less likely to wear a seatbelt when passengers were present, than when driving solo. Drivers age 50 and above had higher seatbelt use rates when passengers were present. This protective effect of passengers was stronger for male drivers than female drivers, and for male drivers the effect increased by age. Drivers age 15-34 accompanied by passengers were more likely to have consumed alcohol than solo drivers of the same age group. These results offer an interesting perspective for research in the area of driver distraction, and update current knowledge on older drivers and the role of seatbelt and alcohol awareness.

Ragland, David R.
Publication date: 
November 15, 2004
Publication type: 
Technical Report