Head-Throw Distance (HTD)
Definition
The horizontal distance from the vehicle's front bumper contact zone to the final rest position of the pedestrian's head; used in the Searle (1993) biomechanical model to estimate the vehicle's impact speed.
- Definition
- Bumper contact zone to head's final rest position
- Measured plane
- Horizontal
- Model
- Searle model (1993)
- Application
- Vehicle impact speed estimation
Common questions
What besides impact speed affects head-throw distance?+
Pedestrian height and weight, the vehicle's front-end profile, road surface friction, and whether the body underwent secondary impacts all influence the final rest distance, so HTD is one input among several in a reconstruction.
Why do investigators need precise contact and rest points, not an approximate distance?+
The Searle model fits an empirical throw-distance curve to estimated speed, so an error of even a metre in locating the contact zone or the head's final position can shift the calculated speed noticeably.
Related terms
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