Forensic Evidence Relating to Motorcycle Pre-Crash Maneuvers

7th International IFZ Motorcycle Conference
Cologne, Germany, 2008

Co-Author(s): Stein E.Husher, Michael S. Varat, Christopher D. Armstrong, John C. Steiner

When analyzing collisions involving powered two wheelers, often, the determination of pre-crash maneuvers is sought. These pre-crash maneuvers generally involve braking and cornering which can leave evidence on the roadway or on the tire. This roadway evidence, when present, generally consists of tire marks which can result from both braking and steering. Observed vehicle evidence from precrash maneuvers often consists of surface modifications on the tires which can provide information relating to the severity of the braking and cornering motions. The present research is undertaken to evaluate observable scene and vehicle evidence based on documented motorcycle dynamics during pre-crash braking and steering. Case studies from real world collisions are presented. Braking test data is presented and roadway and vehicle evidence is described. A series of riding tests were performed and the vehicle dynamics and associated tire evidence was documented. It was found that if roadway evidence from some pre-crash maneuvers is overlooked by the on-scene investigator, careful analysis of the motorcycle tires can yield valuable information relating to the severity of the maneuvers performed. Additionally, motorcyclist utilization of available vehicle performance may be evident from the condition of the motorcycle tires at the post event analysis. This careful tire documentation, as a crash research technique, provides valuable information not available from other sources.