Crumple zones

The bespectacled man in the photo below is the automobile engineer Bèla Barènyi. In 1937, when he was 30, Barènyi came up with the idea of crumple zones for cars. To protect occupants in the event of head-on or rear-end collisions, Barènyi proposed that cars should consist of three cells: a strong, rigid, central cell that would house the driver and passengers, and weaker cells front and back that would absorb the energy of a crash by deforming plastically.

The first production cars to incorporate crumple zones belonged to the W111 series made in 1958–59 by Barènyi’s employer, Mercedes-Benz.

Another car that incorporated crumple zones was my 1993 Honda Civic hatchback. I use the past tense because yesterday my wife and I were involved in a four-car pile-up on US Route 1 just outside the Capital Beltway. The car’s front end was indeed crumpled, but none of the four cars’ six occupants was seriously injured.

The accident was caused by a driver of a Ford Taurus, who apparently went into diabetic shock and failed to stop or even apply the brakes when the traffic light ahead of him turned red. The Taurus hit a Toyota Camry, which hit my car, pushing it into a Nissan Xterra.

Because the Toyota driver and I were still braking, the first two collisions, Ford–Toyota and Toyota–Honda, were mostly elastic. The Nissan ahead of us had come to a complete stop. The last collision, Honda–Nissan, was therefore inelastic, as you can see from the photo.

When a car that doesn’t have a crumple zone smashes into something at high speed, its entire frame, including the passenger compartment, can buckle and its front end, including the engine if it’s in the front of the car, can be pushed into the passenger compartment. As Barènyi recognized 74 years ago, either consequence imperils passengers.

The collision my wife and I were involved in was at low speed. If the car didn’t have crumple zones and had instead a rigid frame, I doubt we’d have been crushed by a buckled frame or pushed-in engine.

But the crumple zone spared us from injury in another way. Thanks to its crumple zone, my car took longer to decelerate when it was slammed into the Nissan than a rigid car would have done. That extra time meant that our heads required less force from the objects that brought them to rest: our necks.