Quad-bikes, also known as all-terrain vehicles in the United States of America, continue to be a major contributor to fatal and serious injuries in Australia as well as in many other countries all over the world, both for recreational use and in the workplace. There have been over 150 fatalities caused by quad-bike incidents in Australia since 2000 with around 70 percent of these attributed to rollovers. In 2011, quad-bikes overtook tractors as the leading cause of injury and death on Australian farms.

There is a significant portion of quad-bike fatalities that are identified as being caused by riding over a raised obstacle (i.e. bump, log, tree stump, etc.), which causes the vehicle to lose control and rollover. However, the authors are not aware of any research that has been published to date in regards to identifying the mechanism that causes this loss-of-control situation in the case of quad-bikes. This paper details a novel method used to identify this mechanism.

Preliminary testing conducted with a human test rider, identified that a rider can be significantly displaced across the seat when riding a quad-bike over a semi-circular raised obstacle placed on one side of the vehicle wheel track. A formal test procedure was then developed to measure the pelvis kinematics of an Anthropomorphic Test Device mounted on a quad-bike moving over a 150mm high bump obstacle placed on one side of the vehicle wheel track. This procedure was then simulated using a Finite Element (FE) model of a quad-bike that was validated against experimental tests. The analysis of both experimental and FE simulation results presented here clearly demonstrate how a quad-bike loss-of-control event, leading to rollover, can be triggered by a bump-like raised obstacle.