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When a motorcycle collides with a passenger vehicle, the impact can cause a change in the translational and rotational velocities of the struck vehicle. If these velocity changes, or the magnitude of the translation and rotation of the struck vehicle can be quantified, then these can potentially be used to calculate the impact speed of the motorcycle. There are several methods that could be used for this analysis. The most general and comprehensive solution will be to use one of the widely-accepted accident reconstruction simulation programs - PC-Crash, HVE (the EDSMAC4 or SIMON modules), Virtual CRASH, or VCRware. However, these simulation programs can be time-consuming to apply and not everyone has access to them. It would be useful to have simple formulas for obtaining a reasonable estimate of the motorcycle impact speed based on the observed post-impact translation and rotation of the struck vehicle.

This paper reports testing and analysis of the braking and swerving capabilities of on-road, three-wheeled motorcycles. A three-wheeled vehicle has handling and stability characteristics that differ both from two-wheeled motorcycles and from four-wheeled vehicles. The data reported in this paper will enable accident reconstructionists to consider these different characteristics when analyzing a three-wheeled motorcycle operator’s ability to brake or swerve to avoid a crash. The testing in this study utilized two riders operating two Harley-Davidson Tri-Glide motorcycles with two wheels in the rear and one in the front. Testing was also conducted with ballast to explore the influence of passenger or cargo weight. Numerous studies have documented the braking capabilities of two-wheeled motorcycles with riders of varying skill levels and with a range of braking systems.

Many motorcycle crashes involve the motorcycle capsizing, impacting the ground, and sliding on the road surface. When performing speed calculations, the energy or speed loss for the ground impact and sliding phases may need to be calculated. To perform these calculations, the reconstructionist will typically determine the slide distance based on the physical evidence and then apply a range of decelerations over that distance based on test data in the literature. Decelerations can be selected for motorcycles with similar characteristics (crash bars, panniers, fairings, etc.) sliding on similar surfaces (asphalt, concrete, dirt, gravel, etc.). This approach is adequate but sometimes results in a wide range due to the variability in reported decelerations in prior studies. It could be helpful to narrow the likely range of decelerations, and thus, the speed range.

Accident reconstruction utilizes principles of physics and empirical data to analyze the physical, electronic, video, audio, and testimonial evidence from a crash, to determine how and why the crash occurred, how the crash could have been avoided, or to determine whose description of the crash is most accurate. This process draws together aspects of mathematics, physics, engineering, materials science, human factors, and psychology, and combines analytical models with empirical test data. Different types of crashes produce different types of evidence and call for different analysis methods. Still, the basic philosophical approach of the reconstructionist is the same from crash type to crash type, as are the physical principles that are brought to bear on the analysis.