Analysis of Roadway and Tire Evidence Resulting from Aggressive Braking Maneuvers with ABS-Equipped Motorcycles 2023-01-0635

With ABS-equipped motorcycles becoming more pervasive, it is critical for collision reconstructionists to have a firm understanding of what evidence may be generated during aggressive braking events performed with these braking systems. To develop a better understanding, thirty-one instrumented braking tests were performed and are reported in this study. Three different surfaces using three current ABS-equipped motorcycles were used to study the residual visible roadway and tire evidence resulting from hard braking events involving front-only, rear-only, and maximum effort braking maneuvers. Data from these tests were analyzed to determine the resultant deceleration, which serves to add updated data to the current body of knowledge.

The majority of braking tests did not generate visible roadway evidence. Specifically, conventional public roadway surfaces exhibited no evidence of braking until the motorcycles reached very low speeds. One surface, a residential roadway with a recently applied chip seal, repeatedly displayed evidence of braking in the form of subtle, light discolorations. Conversely, all test runs produced distinct circumferential speckling on the braked tire(s) that was accompanied by localized tread abrasion when intermittent locking occurred. The average decelerations achieved during the braking maneuvers were -0.42 g, -0.80 g, -0.88 g for rear-only, front-only, and both brake configurations, respectively. These findings demonstrate modern ABS-equipped motorcycles are not likely to generate discernible roadway evidence as result of a hard braking event and highlight the need to promptly document the tires of a motorcycle involved in a collision, as the tire offers the most reliable evidence of hard braking.