An Assessment of the Effects of Vehicle Weight and Size on Fatality Risk in 1985 to 1998 Model Year Passenger Cars and 1985 to 1997 Model Year Light Trucks and Vans 2005-01-1354

An understanding of the independent effects of vehicle weight and size on overall vehicle safety is necessary in order to assess the risks and benefits of vehicle weight reduction. This paper describes the results of statistical analyses of 1985 to 1998 model year passenger cars and 1985 to 1997 model year light trucks and vans (LTVs) involved in traffic accidents in the US from 1995 to 1999 to quantify these effects. The analyses involved aggregate linear regression and logistic regression of US FARS fatal accident data, state accident data, and vehicle registration data, using methods based on or adapted from methods described in published NHTSA Technical Reports. The results indicate that 1) reduced vehicle curb weight would decrease the total number of fatalities (including occupants of other collision partners and vulnerable road users), 2) reduced vehicle wheelbase and/or track would increase the total number of fatalities, and 3) that the effect on fatalities of reduced vehicle curb weight, wheelbase, and track according to the trends among these three variables in the 1985 to 1998 model year cars and 1985 to 1997 model year LTVs is small because the opposing effects of these variables tend to cancel each other. The sensitivity of these results to different assumptions and statistical methods was also assessed.