The primary purpose of the Technical Accident Reconstruction (TAR) Unit is to examine, analyze and formulate conclusions related to specific issues in motor vehicle collisions. These issues include, but are not limited to pre-impact speed of vehicle(s) as determined from roadway and vehicle evidence, temporal and spatial relationships of vehicles prior to a collision, existence of vehicle defects which contributed to a collision, and forensic mapping of collision scenes.

In the past several years the TAR Unit has used new technology to become more efficient and effective. The days of placing tape measures on the roadways to collect data from a collision scene are fading away. In 1996 the unit received total stations to better collect evidence at collision scenes, which provide more accurate post-collision scaled diagrams. The unit now uses a system known as Photogrammetry to collect that evidence in less than 25% of the time, which assists troopers in clearing roadways to reduce traffic delays and residual collisions.

While all Troopers are taught to be proficient in basic accident investigation, some incidents involve complex technical issues that require the expertise of personnel with special training. Members of the TAR Unit have such training and are available to assist members of the Division of State Police and any other law enforcement agency within New Hampshire. Unit members receive specialized training in Motor Vehicle Reconstruction, Crash Data Retrieval, Forensic Mapping, and Computer Drawing. Additionally, members receive training in Photogrammetry and the Crash Zone drawing program.

Unit members collectively conducted 39 investigations during 2007.