When a vehicle is involved in a collision, often a question arises regarding the vehicle's pre-crash velocity. In modern vehicles, velocity data can typically be extracted from the vehicle's Electronic Data Recorder (EDR) via OEM or aftermarket diagnostic tools. However, many modern vehicles - and particularly vehicles operated and/or manufactured in Australia - are not equipped with downloadable EDRs. In these cases, the pre-crash velocity must be calculated based on physical forensic evidence.
One method for estimating collision velocity is the crush-energy method, wherein the vehicle is modeled as a spring system. The velocity is then estimated based on the vehicle-specific stiffness properties and on the post-collision crush profile. The vehicle-specific stiffness properties must be derived from a comparable staged crash test. Often, no such crash test exists.
This paper documents a method wherein the stiffness of the vehicle is estimated using compendium data which has been methodically-distilled from the NHTSA crash test database. An analysis is presented which identifies key parameters that should be considered when distilling the data, including vehicle type, vehicle vintage, vehicle mass and vehicle wheelbase.