Most people think of a car accident as a single event – one vehicle striking another. In reality, every crash involves a devastating chain reaction of multiple impacts occurring within fractions of a second.
Safety experts and personal injury professionals often refer to this as the three-step progression of a car crash or the three collisions in every car accident:
1. The vehicle collision
2. The human collision
3. The internal collision
Understanding these three stages helps explain why even seemingly “minor” accidents can cause serious injuries. It also highlights why seat belts, airbags, head restraints, and modern vehicle safety systems are so important.
The Physics Behind a Car Crash
Before breaking down the three collisions, it helps to understand one key principle of physics: objects in motion stay in motion until acted upon by another force.
When a moving vehicle suddenly stops during a crash, the occupants inside continue traveling at the vehicle’s previous speed until something stops them.
This entire sequence happens incredibly fast – often in less than a second.
Collision #1: The Vehicle Collision
The first collision is the actual crash between the vehicle and another object. During this phase:
- Metal crumples
- Glass shatters
- Bumpers collapse
- Energy transfers through the vehicle
Modern vehicles are intentionally designed with crumple zones that absorb some of the impact energy to reduce the force transferred to occupants.
Even so, the sudden deceleration forces generated during a collision can be enormous – especially at higher speeds.
Collision #2: The Human Collision
The second collision occurs when the occupant’s body continues moving forward and strikes part of the vehicle interior. This may include:
- The steering wheel
- Dashboard
- Seatbelt
- Airbag
- Side window
- Headrest
- Door frame
- Windshield
This second collision is often responsible for many visible traumatic injuries.
Common Injuries From the Human Collision
Depending on the severity of the crash, the human collision may cause:
- Whiplash
- Broken bones
- Concussions
- Facial injuries
- Dental trauma
- Neck injuries
- Spinal cord injuries
- Shoulder injuries
- Knee injuries
- Traumatic brain injuries (TBIs)
Seat belts and airbags help reduce injury severity by spreading crash forces over stronger parts of the body and slowing occupant movement more gradually.
However, even properly restrained occupants can still suffer serious injuries due to the tremendous forces involved.
Collision #3: The Internal Collision
The third collision is often the most dangerous – and the least visible. This occurs when the body’s internal organs continue moving after the body itself has stopped.
Even though the occupant may appear externally stable, the organs inside the body continue traveling until they collide with:
- Bones
- Other organs
- Internal body structures
For example:
- The brain may collide with the inside of the skull
- The lungs may compress against the ribcage
- Internal organs may tear or bleed
- Blood vessels may rupture
This internal movement can cause life-threatening injuries even when there are few visible external signs of trauma.
Common Internal Collision Injuries
- The internal collision may lead to:
- Traumatic brain injuries
- Internal bleeding
- Organ damage
- Aortic injuries
- Rib fractures
- Lung injuries
- Abdominal trauma
- Spleen or liver damage
Some internal injuries may not present symptoms immediately, which is why medical evaluation after a crash is extremely important.
Why Some Injuries Appear Later
After an accident, adrenaline and shock can temporarily mask pain and symptoms. Injuries associated with the internal collision may take hours or days to fully develop. Common delayed symptoms include:
- Headaches
- Neck stiffness
- Back pain
- Dizziness
- Numbness
- Abdominal pain
- Memory issues
- Fatigue
Seeking prompt medical attention after a crash can help identify hidden injuries early and create documentation important for both health and legal claims.
Every car accident involves more than just vehicles colliding. The three-step progression of a crash – the vehicle collision, the human collision, and the internal collision – demonstrates how quickly and violently the human body can experience trauma during an accident.
Even crashes that seem minor can result in significant injuries due to the immense forces involved. That is why wearing seat belts, maintaining safe driving habits, and seeking medical attention after an accident are so important.
