Losing Weight To Save Lives: A Review of The Role of Automobile Weight and Size In Traffic Fatalities

Reductions in vehicle weight will be necessary to dramatically increase vehicle fuel economy and address concerns about global warming. The purpose of this report is to explore the relationship between vehicle weight and fatalities in traffic accidents. One of the most interesting possibilities is to use new technologies to reduce vehicle weight while maintaining
vehicle size to protect occupant safety.

Two-vehicle crashes are the largest source of traffic fatalities, accounting for 43% of traffic fatalities in 1999. Fatalities in car-to-car crashes have sharply declined even while the number of cars on the road has gradually increased. Car-to-car head-on fatalities dropped 35% in the 1980s and did drop another 25% in the 1990s. If one looks at fatalities in new cars only, the
decline is even more rapid—an 80% decrease for 1980–97! The consequences of car-to-car head-on fatalities have been revolutionized by protection technology, motivated in part by the standardized crash test. Seat belts and air bags are increasingly effective in protecting occupants. Powerful computer-assisted efforts also enable safety improvements in the design and manufacture of vehicle structures.

Light trucks crashing with cars now cause many more fatalities than cars crashing with cars. Collisions where trucks strike cars on the side are now the largest cause of fatalities in twovehicle crashes. Over two thousand lives would be saved annually by establishing “compatibility” between cars and light trucks.2 This means reducing the mass differential between cars and those light trucks used as car substitutes by making the heavier vehicles lighter. Compatibility in height and stiffness is also required—for example, for the front of the striking vehicle (truck) and the side of the struck vehicle (car). Compatibility involves both vehicles: The lighter cars would not be made still lighter, but would be made larger in selected
ways.