Crumple zone

The crumple zone is a structural feature mainly used in automobiles and recently incorporated into railcars.

Crumple zones are designed to absorb the energy from the impact during a traffic collision by controlled deformation. This energy is much greater than is commonly realized. A 2,000 kg (4,409 lb) car travelling at 60 km/h (37 mph) (16.7 m/s), before crashing into a thick concrete wall, is subject to the same impact force as a front-down drop from a height of 14.2 m (47 ft) crashing on to a solid concrete surface. Increasing that speed by 50% to 90 km/h (56 mph) (25 m/s) compares to a fall from 32 m (105 ft) - an increase of 125%. This is because the stored kinetic energy (E) is given by E = (1/2) mass × speed squared. It increases by the square of the impact velocity.