In Preparing and Presenting Expert Testimony, traffic engineer and accident reconstruction expert witness Lawrence Levine writes:
Case Preparation As Traffic Engineers, our goal is to provide safe movement on highways and streets. However, all too often accidents occur resulting in injuries and property damage, from which lawsuits often arise. The lawsuit, which in this case would either be criminal or civil, is the basic manner in which money is distributed and justice served to the injured parties. In a criminal case (involuntary manslaughter, for instance) the question is “who dunnit?” and “was it intentional – was there a motive – why did they do it?” A civil case, however, involves the question of “what were the proximate cause(s) which enabled the injuries and damages to occur?” An example of a civil case would be if a party’s vehicle hits a signal pole which is unprotected and installed too close to the road, and thereby becomes injured. These are two fundamentally different issues. The Criminal case generally deals with investigating people, determining wrongdoings, and consequently assigning blame and doling out punishment accordingly. Traffic Engineers can become involved in criminal cases as Accident Reconstructionists or in determining if there was some sort of criminal malfeasance in the construction of a project which consequently failed and caused injury. However, generally traffic engineers are involved as experts in civil cases where the injured party seeks relief through monetary judgments.