Join Everyday Law as we discuss accident reconstruction with Sgt. Andrew Thomas of the McHenry County Sheriff’s Office. Sergeant Andrew Thomas works for the McHenry County Sheriff’s Office. He also does accident investigation and reconstruction through his own company, Collision Analytics, LLC, (, for accidents outside McHenry County. In addition to his job for McHenry County and his business, Thomas teaches classes in accident investigation and reconstruction at the Northwestern University Center for Public Safety.

Thomas originally started studying architecture in college but changed majors after a good friend suffered serious injuries from an automobile crash. This event led him to study criminal justice at Western Illinois University. While a college student, Thomas worked for the McHenry County Sheriff’s Office. He obtained full-time employment with McHenry County after he finished his education. Thomas started as a patrol deputy and later was assigned to crash investigation. He took further coursework in crash investigation and accident reconstruction at the Northwestern Center for Public Safety. His experience, education and interest in this subject led to starting his own business and teaching about the subject at Northwestern.

Law enforcement personnel learn about crash investigation and accident reconstruction not only to know who is at fault and who gets the ticket; a bigger issue is transportation safety. County and state agencies study and analyze local traffic accident reports to look at issues of engineering of roadways, vehicle safety and driver behavior like distracted driving.

Law enforcement personnel first learn about accident investigation. They learn to collect and document the physical evidence. This evidence includes the vehicles, the environment or scene of the accident and the people involved in the accident and any witnesses. Accident reconstruction follows accident investigation and takes all of the physical evidence and determines how the accident occurred.

Accident Investigation and reconstruction is always evolving. One aspect of documenting an accident scene might be measuring skid marks to calculate velocity of vehicles. However, with the advent of ABS (anti-lock braking system) in most cars, heavy skid marks on roadways are a thing of the past. A different technological advance in autos that assists in accident investigation is the “black box” or event data recorder for air bag systems. These recorders were installed in autos to help manufacturers understand how well the air bags were working. An additional benefit to investigators and reconstructionists is the data recorded by these recorders. These recorders, when activated, can be a valuable source of information about what the driver was doing moments before the crash. These recorders record data regarding speed, braking, throttle, steering wheel angle and the severity of the crash.

Thomas’ passion for accident investigation and reconstruction leads him to do as much as research and investigation as possible in this field through his work with the McHenry County Sheriff’s Office, his business and teaching. He derives satisfaction from his work especially in the case of serious or fatal accidents where his investigative work can provide answers and understanding as to why an accident occurred. He currently finds distracted driving to be one of the toughest issues for law enforcement.