NHTSA RELEASES STUDIES ON RELATION OF VEHICLE SIZE TO OCCUPANT SAFETY |
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National Highway Traffic Safety Administration (NHTSA)
June 10, 1997
FOR IMMEDIATE RELEASE
Tuesday, June 10, 1997
NHTSA 387-97
Contact: Tim Hurd
Tel. No. (202) 366-9550
NHTSA RELEASES STUDIES
ON RELATION OF VEHICLE SIZE
TO OCCUPANT SAFETY
The National Highway Traffic Safety Administration (NHTSA) today released a summary report backed by six technical studies describing how a vehicle's size affects the safety of its occupants and the safety of those sharing the road.
"These studies, which have been peer-reviewed by the National Academy of Sciences, lay out in detail the impacts associated with size and weight of vehicles on the road," said Ricardo Martinez, M.D., NHTSA's administrator and an emergency physician.
Light trucks (pickups, vans and sport-utility vehicles), on the average, weigh 900 pounds more than passenger cars. NHTSA records show that each year since 1992, there have been more fatalities in car-light truck collisions than there have been in car-to-car collisions. In car-light truck collisions, 80 percent of the fatalities are occupants of the cars. Continued growth in disparity of size and weight, as between light trucks and passenger cars, unless offset by safety improvements, could be expected to increase the number of deaths and injuries on the road.
One of the studies analyzed the crash experience of model year 1985 through 1993 passenger cars and light trucks, and compared the rates at which lighter and heavier vehicles were involved in crashes involving fatalities ("fatal crash rate") and those resulting in moderate-to-critical injuries ("injury crash rate").
Another study found that the fatal crash rate for passenger cars increased by 1.1 percent for each 100 pound decrease in passenger car weight. The injury crash rate for these vehicles increased by 1.6 percent for each such reduction. These findings suggest that a future 100-pound reduction in passenger car weight, unless offset by safety improvements, could result in an estimated 302 additional fatalities and 1,823 moderate-to-critical injuries per year.
The studies showed the relationship to be reversed in the case of light trucks. Reductions in the weight of light trucks reduce risks for car occupants, pedestrians, bicyclists and motorcyclists involved in collisions with the trucks. As a result, the fatal crash rate involving light trucks decreased by 0.3 percent for each 100-pound decrease in light truck weight and the injury crash rate decreased by 1.3 percent. As such, a future 100-pound reduction in the weight of light trucks would be expected to prevent 40 fatalities and 601 moderate-to-critical injuries per year, most of these being occupants of other vehicles or pedestrians involved in crashes with light trucks. This more than compensates for the added risk to the occupants of the trucks. A future increase in the weight of light trucks would have the opposite effect.
NHTSA noted that the outcomes of crashes involving light trucks are not exclusively a function of the differential in size and weight. In addition, light trucks generally have a more rigid structure than passenger cars. Also, the higher front ends of light trucks have a tendency to override the lower structures of passenger cars.
NHTSA has active research programs underway to study these emerging issues of compatibility within the vehicle fleet. Specifically, NHTSA has established a special working group of the agency's Motor Vehicle Safety Research Advisory Committee (MVSRAC) to study and advise the agency on the topic. Additionally, as part of its effort to encourage harmonized, internationally coordinated research on safety issues with international implications, NHTSA is participating with a host of other nations on a joint international research effort on the topic.
The goals of both research efforts in the near term are to identify and demonstrate the extent of the problem of incompatible vehicles in multi-vehicle collisions. The longer term goals are to develop procedures to evaluate aggressivity and compatibility, leading to the development of appropriate countermeasures.
The NHTSA studies will be placed in a public file for comment, docket 97-033, no. 1. The public docket is in room 5111, 400 Seventh St., S.W., Washington, D.C.