Methods: Mathematical modeling of a real-life ATV event was utilized. A video was selected from our YouTube ATV crash video library that illustrated a specific ejection mechanism of a pediatric ATV operator. Measurements from the video were used in a kinematic model to calculate the conditions that would result in ejection of the youth from the ATV upon sudden deceleration. The mass and grip strength of the youth along with the velocity and deceleration distance were determined. A speed was then calculated for the force necessary to break the grip and result in ejection.
Results: The rider was determined to be a female of approximately 11 years of age with an estimated grip strength of 350 Newtons. The deceleration distance was estimated at 1 meter. The velocity range of the vehicle during the video was determined to be from 3-5 meters/sec (6.7 to 11.2 mph). Based on these parameters, we calculated that sufficient force to break the child's grip (>350 Newtons) during deceleration would be achieved at the relatively low speed of 10 mph.
Conclusion: Videos on social media sites provide a natural experiment for studying ATV crashes and injuries. Kinematic modeling can then be used to determine threshold values beyond which the crash and injury will occur. Results from these studies will be valuable for educational and engineering approaches designed to prevent ATV crashes and/or reduce their impact. Our study demonstrates that dangerous conditions which could result in an ejection of a youth ATV operator were easily within the range of the normal riding environment.