Virtual crash-test dummy.

Automobile manufacturers seeking to build safer cars have traditionally relied on one procedure for safety-testing their new models: Build 'em and crash 'em.

Such tests involve placing humanlike models-known as crash-test dummies-behind the wheel and in the passenger seats of a vehicle, then propelling it into a brick wall. Scientists gather data on potential injuries from sensors in the dummies.

William O. Wray, an aerospace engineer at the Los Alamos (N.M.) National Laboratory, and his colleagues are now designing a computer system to simulate crash tests.

"We're developing a human body model for use in crash-worthiness calculations," he says. Simulations are less expensive than crash tests and can be performed earlier in the design process, considerations that he expects will prove attractive to auto manuf acturers.

"The goal is to identify areas of the body that might be injured," Wray adds.

Auto designers would first run a model of the entire human body in a simulated crash to get a sense of where injuries might occur. A second round would focus on detailed models of the head, spine, or other area of the body to observe subtle damage. Wray b elieves the simulations would enable automobile companies to fine-tune new designs, making cars safer for people of different body types and sizes.

The computerized crashes could also reduce design-to-production time by 3 months, Wray estimates. "We think the number of crashed vehicles can be cut by 15 to 20 percent," he says. "There will still be crash tests, but the better the computer models are, the fewer cars you have to destroy." Each crash tests costs roughly $750,000.