How many separate crashes occur on impact in a collision?

In a collision, the concept of separate crashes refers to the sequential impacts that occur at different points during the crash event. Each impact can be identified as a distinct crash due to the changes in momentum and the forces acting upon them.

When an initial collision occurs, the first impact is often between the two vehicles involved. Following this, the occupants of each vehicle experience a secondary impact as they collide with the interior of their own vehicle, which is commonly referred to as the "human impact." This involves the person’s body hitting the steering wheel, dashboard, or seats. Additionally, there can be a third impact wherein the occupants may also experience additional forces, such as being thrown against seatbelts or airbag deployment.

This understanding correlates with the three-crash concept, which allows for a comprehensive analysis of the dynamics involved during a collision. Recognizing these impacts can help in understanding the consequences of vehicle crashes from both a safety and legal perspective.