There are numerous tools available to scientifically calculate the speed of a vehicle at the time of the crash from the basic skid-to-stop formula, momentum and energy analysis, and simulation. All of these calculations rely on the crash scene evidence from the roadway to determine distances. The specific process used to calculate vehicular speeds is determined by the type and amount of physical evidence that is available or can be obtained.
Police scene measurements can be used when they are available. If scene measurements were not conducted, Neese & Associates uses an electronic measuring system to measure the crash site. In some instances, photogrammetry is used to get accurate distances from the available investigative scene photographs. Pre-collision paths and post-collision paths are documented and relied upon in a momentum analysis to determine speed.
Inspecting and measuring the vehicles help determine the amount of energy needed to damage the vehicles. The energy analysis is another scientific method that is commonly relied upon in the reconstruction arena.