Crossing the Road To Pedestrian Safety

Autoliv's new protection system for pedestrians lifts the hood to provide a 'softer landing' for the head and reduce the risk of contact with rigid engine and structure parts underneath (Autoliv North America)

"We could never verify that the standard would actually have any particular benefit because then, as now, it's very difficult to know precisely what injury was inflicted by the vehicle and what injury was inflicted by contact with the pavement," said Rae Tyson, spokesman for the National Highway Traffic Safety Administration.

Simulating the effects of a crash on a pedestrian is more difficult than testing for vehicle occupants, said Jeff R. Crandall, director of the Center for Applied Biomechanics at the University of Virginia. "If you take a driver, he's in a defined position -- behind the steering wheel, hopefully belted -- so you sort of know where they are. For pedestrians, there's a whole host of sizes, positions, geometries -- so it's a very, very challenging issue from a design standpoint," Crandall said.

Crandall's lab uses cadaver parts to test the effects of stress on human legs, the head and other areas of the body, then takes that information to help create crash dummies and computer simulations to see what happens in different types of vehicle impacts.

When struck by a car, adults tend to suffer leg damage, then fall up onto the hood, with the head hitting around the base of the windshield. Little can be done to help someone who gets hit at speeds over about 30 mph. The safety standards going into effect this fall in Europe are aimed at reducing the damage from striking the hood at speeds under 25 mph.

Honda has already taken steps to address that issue, beginning with a redesign of the Civic in 2001 and spreading to other models in the years since. In each model, engineers repackaged the engine to create three to four inches of space under the hood, so the sheet metal can absorb most of an impact. Honda also redesigned windshield wiper arms so they would break away when struck.

"We're determined to be leaders in safety, and you don't want to just wait around for legislation," said Charles R. Barker, head of research and development for Honda in the United States. The company also is looking at radar systems that could sense a person in the vehicle's path and apply brakes automatically, Barker said.

The company sponsors some of Crandall's research at the University of Virginia, as well as a program at Inova Fairfax Hospital that investigates real-world accidents to look for ways to lessen injury. Honda claims its design changes should result in a 5 percent decrease in pedestrian fatalities per year compared with vehicles without such measures, saving about 20 lives annually -- though it's too soon for hard data to back up those numbers.

Further design changes will be needed to meet stricter standards proposed in Europe in 2010, which involve reducing head and leg injuries. Some of those changes involve creating softer bumpers that would not meet U.S. minimum safety standards, said Tyson, the NHTSA spokesman.

Such trade-offs make the issue complicated, said Adrian Lund, chief operating officer at the Insurance Institute for Highway Safety, a safety center funded by the insurance industry. "I think there's a good deal of uncertainty as to what the level of benefit will be" from the pedestrian safety design changes, he said.

The uncertainty is greater in the United States than in Europe, he said, because the vehicle fleet here has much more variety. In the United States, more than half of all new vehicles sold each year are pickups or sport-utilities with high, flat front ends, while Europe and Japan are more uniformly populated by cars.

Consumers might not be willing to pay more for pedestrian safety, which, after all, is aimed at protecting someone outside the vehicle, Lund said. "We're not sure how much attention even people in Europe are paying to those [pedestrian safety] ratings because what they're most concerned about is protecting their own families inside the vehicle."

Wimberly, the Fairfax police officer, said he thinks U.S. money would be better spent on redesigning roadways to reduce danger to pedestrians -- adding raised crosswalks, for instance, and putting more designated crossing areas in the car-heavy suburbs.

But even within the law enforcement community, he said, there is disagreement over how to improve pedestrian safety. "Everyone has got an opinion," said Wimberly, who oversees the department's crash reconstruction unit. "From the design of hoods and bumpers . . . [to] a combination of air bag deployments for pedestrians and catching devices to keep them from being thrown over the roof -- you name it, and it's out there."

Autoliv Inc., a leading supplier of air bags to carmakers, has developed an air bag that deploys on the outside of a vehicle near the base of the windshield, to lessen pedestrian head injuries. The company said it's working on the device with several auto manufacturers looking to meet Europe's 2010 regulations, though it wouldn't name them.

Autoliv also has signed a contract with one customer for an "active" hood device, which uses a pyrotechnic charge to raise the hood slightly on impact.

Such technology will inevitably find its way to the U.S. market because of the increasingly global nature of the auto industry, U-Va.'s Crandall said. And that's good, he added; one of the groups most at risk for pedestrian injury is the elderly, and the U.S. population is aging rapidly.

"I really think this issue is something that needs to be looked at at this time," Crandall said. "Not just passively make the judgment that we don't have problems, but actively look at it to do something about it."