If a vehicle strikes a tree at 60 MPH, the unrestrained driver would experience the MOST severe injuries during the:

• A. First collision
• B. Second collision
• C. Third collision
• D. Fourth collision

Answer: (C)

In a high-speed crash, injuries happen in stages as energy is transferred through the body. The first collision is the vehicle hitting the tree. The second collision is the occupant striking the inside of the car, such as the chest or head contacting the dash or steering wheel. The third collision is the internal organs moving within the body and then striking solid structures like the rib cage, spine, or abdominal walls.

With an unrestrained driver at 60 mph, the momentum keeps the organs moving after the second collision, so they slam into the inside of the body. This can cause severe lacerations, ruptures, and major bleeding from organs such as the liver, spleen, and mesentery, as well as potential damage to the great vessels. Those internal injuries are often life-threatening and are typically more immediately dangerous than injuries from the first collision or the brain’s contact with the skull (the fourth collision). Hence, the third collision represents the stage where the most severe injuries commonly occur in this scenario.