What looks like a mass of crumpled sheet metal is actually a carefully orchestrated event. Crush decreases the speed of deceleration during a crash. In other words, engineers want to have crush in the vehicle to prevent the crash forces frombeing too high. Because the passengers will continue to travel at the same speed as the vehicle, reducing the speed of deceleration will also reduce the passengers' injury risk. Seat belts and airbags inside the car manage the remaining deceleration forces and keep the passengers in position, to prevent injuries from hitting the steering wheel, windshield or dashboard.
Force acting on the body is more modest because it has broad distribution.
Airbags make the area which force acts upon even larger. In addition, we can control where the seat belt hits the body. The seat belt is designed to cross over bony structures where the risk of physical injury is lowest. According to Lange, engineers face a different challenges in designing crush zones for the two types of construction. Trucks will take a significant amount of crush in the frame structure.