ATV Dynamics and Pediatric Rider Safety

It has been observed through numerous academic and governmental agency studies that pediatric all-terrain vehicle ridership carries significant risk of injury and death. While no doubt valuable to safety, the post-hoc approach employed in these studies does little to explain the why and how behind the risk factors. Furthermore, there has been no prolonged, widespread, organized, and concerted effort to reconstruct and catalog the details and causes of the large (20,000+) number of ATV-related injuries that occur each year as has been done for road-based motor vehicle accidents. This dissertation takes the opposite approach from a meta-analysis and instead examines the injury risk factors through a two-pronged, a priori, physics-based approach. Specifically, this dissertation study sought to: 1) experimentally determine whether age is an effective metric for assessing proper rider fit on an ATV, and 2) demonstrate experimentally and analytically how the combined dynamics of the ATV and riders can contribute to vehicular instability. These two studies were conducted using instrumented human subjects and ATVs and measured in a biodynamics laboratory. The key finding from the rider versus ATV size study was:1) contrary to publicly circulated engine size and age-based fit guidelines, age is not an effective metric for assessing rider fit on ATVs; instead, stature is the more reliable measure. The key findings from the rollover propensity study were: 2a) the combination of common terrain and throttle input can easily lead to a rearwards rollover, with or without additional riders sitting behind the ATV driver, and 2b) the minimum turning radius before initiating a sideways rollover can be easily be exceeded when ATVs are driven on commonly-encountered terrain and at surprisingly low speeds. The results of this dissertation study thus provide new evidence for mitigating two root causes of ATV injury by informing better parental guidance: first, clearly revealing that stature and not age is the key metric for who fits on what ATV model, and second, revealing the ease with which backward and sideways rollovers can occur