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. The results reported here showed that when both the front and rear brakes are utilized, the decelerations produced during braking are consistent with, but in the upper half of, the range of decelerations previously reported for two-wheeled motorcycles. Studies of two-wheeled motorcycles commonly report that most of the deceleration is produced through use of the front brake. The testing reported here showed that the rear brake produced most of the deceleration for the three-wheeled motorcycles used in the testing. In relationship to swerving, this paper examines the accuracy of a commonly-used formula for calculating the longitudinal distance necessary for a swerve of a specified lateral distance. The results showed that, with a modification to the coefficient of this equation, this formula can be used to reasonably estimate the distance necessary for a three-wheeled motorcycle to swerve.