Motorcycle Accident Reconstruction
Nathan’s second book is titled Motorcycle Accident Reconstruction. This book was awarded a silver medal Ben Franklin Award by the Independent Book Publishers Association. As Nathan discusses in his book, a well-founded reconstruction of a motorcycle crash will take into account the unique ways that motorcycles handle and the relationship of the rider to the motorcycle. A motorcycle rider is not attached to or contained by the motorcycle in the same way passenger car drivers are by their vehicles. Oftentimes, a rider will separate from the motorcycle during a crash and will physically strike a car or the ground. Also, the rider’s weight relative to the motorcycle is often greater than a car occupant’s weight relative to the car. Because of this, a motorcycle rider’s body motion and posture can exert significant influence over the motion of the motorcycle. And, of course, motorcycles usually have only two wheels and often capsize during a crash.
On the other hand, a well-founded reconstruction of a motorcycle crash is much like any other accident reconstruction - it is based on physical evidence and on fundamental principles of physics. Conservation of energy, conservation of momentum, Newton's laws of motion, empirical data and physical testing - these are at the core of motorcycle accident reconstruction, just as they are at the core of rollover accident reconstruction, heavy truck accident reconstruction, pedestrian accident reconstruction, roadside barrier impact reconstruction.
Rollover Accident Reconstruction
Nathan’s first book is titled Rollover Accident Reconstruction. A rollover crash is often split into three phases for analysis – the loss-of-control phase or yaw phase; the trip phase; and the roll phase. During the loss-of-control phase, driver steering inputs – or perhaps some other external force – result in the driver losing control of the vehicle. The vehicle enters an unrecoverable yaw during this phase. Analysis of this phase is often aimed at determining the speed of the vehicle when the driver lost control, determining the steering, braking, or acceleration inputs that led to the loss of control, and assessing the reasonableness of those inputs.
The trip phase begins when the trailing side tires of the vehicle lift off the ground and ends when the leading side tires also lift off and the vehicle becomes airborne. Analysis of this phase is often aimed at determining the speed of the vehicle at the beginning of trip, determining the mechanism that caused the trip (i.e., soil, curb, etc.), determining the forces applied to the vehicle by that mechanism, calculating the roll velocity and vertical velocity with which the vehicle entered the roll phase, and analyzing how the occupants moved during this phase.
The roll phase begins when the vehicle becomes airborne. In a rollover that occurs at highway speeds, the vehicle will typically experience multiple vehicle-to-ground impacts during the roll phase. The roll velocity of the vehicle generally ramps up rapidly during the early portions of the roll phase and may level off temporarily after reaching a peak. Beyond the peak, the roll rate tends to ramp down slower than it ramped up until the vehicle comes to rest. Analysis of the roll phase is often aimed at determining the speed of the vehicle when it began rolling, determining the number of rolls the vehicle experienced, assessing the variation of the roll velocity, identifying ground impact locations (along with determining the forces applied to the vehicle during those ground impacts), determining when a particular component was damaged, determining if the occupants were belted, and analyzing when and where during the roll occupants were ejected or injured.
This book addresses each of the phases of a rollover crash in turn. The order flows in the order that a typical reconstruction flows – from the roll phase, to the trip phase, to the yaw phase. Analysis techniques and empirical data for analyzing each phase are discussed.