There are generally five levels of accident investigation recognized in North America. Professional Reconstruction is level four. At this level, the process may be preformed by a single person or a team of investigators depending on the complexity of the crash. The vast majority is performed by a single Reconstructionist. A wide variety of questions may be answered after completing a crash reconstruction, such as speed, time or distance. The focus of the reconstruction may be limited in scope or very broad. The level of accuracy is for the most part controlled by the level of detail to which physical evidence is documented.

REPORTING

Basic data collection to identify and classify a motor vehicle traffic accident and the persons, property and planned movements involved. Strictly, factual information is wanted, no opinions. Level 1 of traffic accident investigation.

AT-SCENE INVESTIGATION

Examine and recording results of the accident and obtaining additional information at the scene of a traffic accident which may not be available later and which supplements data obtained for the accident report. The information is factual as far as possible. Level 2 of Accident Investigation.

TECHNICAL FOLLOW-UP

Collection of additional facts from any source, organization and preliminary study of all available data relating to a traffic accident. Level 3 of accident investigation.

ACCIDENT RECONSTRUCTION

The effort to determine, from whatever information is available, how the accident happened. Reconstruction was formally referred to as determining "behavioral" or "immediate" causes of an accident. Level 4 of traffic accident investigation.

CAUSE ANALYSIS

The effort to determine from whatever information is available, including results of accident reconstruction, why the accident occurred, that is, the complete combination of circumstances that caused the highway transportation system to break down at the time and place of the accident. Cause analysis has been referred to as determining "indirect" or "condition" causes. Level 5 of accident investigation.