Farmer, Charles M.; Lund, Adrian K.
Traffic Injury Prevention
The present study updates a 2006 report that estimated the historical effects of vehicle design changes on driver fatality rates in the United States, separate from the effects of environmental and driver behavior changes during the same period. In addition to extending the period covered by 8 years (now 1985-2012), the new study also estimated the effect of design changes by model year and vehicle type (car, SUV, and pickup).Methods:
Driver death rates for consecutive model years of vehicle models without design changes were used to estimate the vehicle aging effect and, then, the death rates that would have been expected if the entire fleet had remained unchanged from the 1985 calendar year. These calendar year estimates are taken to be the combined effect of road environment and motorist behavioral changes, with the difference between them and the actual calendar year driver fatality rates reflecting the effect of changes in vehicle design and distribution of vehicle types. The effects of vehicle design changes by model year were estimated for cars, SUVs, and pickups by computing driver death rates for model years 1984-2009 during each of their first three full calendar years of exposure, and comparing with the expected rates if there had been no design changes.Results:
As reported in the 2006 study, had there been no changes in the vehicle fleet, driver death risk would have declined during calendar years 1985-93 and then slowly increased from 1993 to 2004. The updated results indicate the gradual increase would have continued through 2006, after which driver fatality rates again declined through 2012. The 1986-97 fleets were less safe than the 1985 fleet would have been, but there was an improvement in safety for the 1996-2012 fleets. Overall, it is estimated that there were 7,700 fewer driver deaths in 2012 than there would have been had vehicle designs not changed. Cars were the first vehicle type whose design safety generally exceeded that of the 1984 model year (starting in model year 1996), followed by SUVs (1998 models) and pickups (2002 models). By the 2009 model year, car driver fatality risk had declined 51 percent from its high in 1994, pickup driver fatality risk had declined 61 percent from its high in 1988, and SUV risk had declined 79 percent from its high in 1988. The risk of driver death in 2009 model passenger vehicles was 8 percent lower than that in 2008 models and about half that in 1984 models.Conclusions:
Safety-related improvements in vehicle design have been key contributors to the historical decline in U.S. motor vehicle occupant crash death rates. From 1993 through 2006, vehicle design improvements appear to have been the primary source of the decline in motor vehicle crash injury risk, while both vehicle improvements and driver/environmental changes, including the economic downturn in 2007, have contributed since 2006. These vehicle changes have been driven by government regulation, the publication of comparative safety test information, and consumer demand. Although these factors have been present since the 1960s, their influence was boosted by the introduction of the U.S. New Car Assessment Program in 1978 and have been particularly strong since the 1990s. Since the early 1990s, environmental and behavioral risk factors have not shown similar improvement, until the recession of 2007, even though there are many empirically proven countermeasures that have been inadequately applied.