Motorcycle Accident Reconstruction:
Applicable Error Rates for Struck Vehicle EDR-Reported Delta-V Nathan Rose William Bortles Neal Carter
I
ntroduction A common motorcycle crash scenario occurs when a passenger vehicle equipped with an Event Data Recorder (EDR) turns left across the path of a motorcycle and is struck by the motorcycle. The EDR data on the passenger vehicle will often be accessible with either the Bosch Crash Data Retrieval (CDR) system or the Global Information Technology (GIT) system. In these instances, pre-crash EDR data can be useful for establishing the specific characteristics of the left turn that preceded the collision. This data may include speed, throttle or accelerator pedal percentage, brake applications, and steering angles for the struck vehicle. In addition to that, an EDR-reported change in velocity (∆V) from the struck vehicle can potentially be used to infer the ∆V and impact speed of the motorcycle. This article reviews and summarizes the literature related to error rates for EDR-reported ∆Vs under various impact conditions and assesses which of these error rates are most applicable when analyzing impacts between motorcycles and passenger vehicles. This lays the groundwork for the companion article [Rose, 2019], which illustrates the application of these error rates within the context of reconstructing real-world intersection collisions involving motorcycles and EDR-equipped passenger vehicles. The companion article also covers the accuracy and application of the pre-crash data from the struck vehicle to these collisions. This article focuses only on the ∆V. There are potential problems that can arise when using the struck vehicle ∆V to infer the ∆V and impact speed of the motorcycle, particularly related to the large weight ratio that often exists between the motorcycle and the struck vehicle. Newton’s 2nd and 3rd laws together (conservation of momentum) dictate that, during a collision between two vehicles, the ratio of the mass of Vehicle #1 (m1) to the mass of Vehicle #2 (m2) is equal to the ratio of the change in velocity experienced by Vehicle #2 (∆V2) to the change in velocity experienced by Vehicle #1 (∆V1), as follows:
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