How does speed influence crash severity?

• A. Higher speeds decrease crash energy.
• B. Lower speeds increase injury risk.
• C. Speed has no impact on crash severity.
• D. Higher speeds increase crash energy, reduce reaction time, and raise injury risk.

Answer: (D)

Speed directly shapes crash severity. The energy that must be dissipated in a collision increases with speed—specifically, kinetic energy rises with the square of velocity—so higher speeds produce much greater impact forces on occupants. That extra energy means more potential for injury. At the same time, faster travel leaves less time to notice hazards and react, reducing reaction time and making it harder to brake or steer away from danger. The combination of greater crash energy and shorter reaction time explains why higher speeds raise injury risk. Choices claiming crash energy drops with speed, or that speed doesn’t affect severity, or that lower speeds are more dangerous, don’t fit how crashes work.