In What is Traffic Accident Reconstruction And Cause Analysis?, accident reconstruction expert witness Patrick Scott Moore writes:
Traffic accident reconstruction is the science of recreating the dynamics of a collision in an attempt to determine the causes. A complete reconstruction requires a complete investigation and analysis of all relevant evidence, statements of the parties and witnesses, and documentation of the collision.
Often, the reconstruction specialist will review and analyze photos and/or videos of the collision scene, police traffic accident reports, statements by the parties/witnessess, reports by claims adjusters, vehicle damage reports by auto body shops, medical reports describing injuries, and any other relevant information regarding the collision.
Usually, unless there are time constraints, the reconstruction specialist will visit the collision site to do a forensic analysis of the environment. This is where the reconstruction specialist must be a good investigator. Collecting good forensic information from the site of the collision requires experience in the skills of identifying, collecting, and preserving evidence.
Once the aforementioned analysis has been conducted, the reconstruction specialist attempts to position the parties prior to, at, and after the impact to better understand the dynamics of the collision to determine the causal factors. Now the reconstruction specialist is ready to form an opinion and testify in court as an expert witness.