Accident reconstruction is a method of testing how a collision may have occurred by comparing physical evidence, measurements, records, and accepted technical methods. It can help answer questions about vehicle movement, impact, speed ranges, visibility, braking, occupant motion, or a component failure. It does not replace reliable source evidence or decide legal responsibility by itself.
What evidence can a reconstruction use?
NHTSA describes detailed crash investigation as a combination of scene inspection, vehicle inspection, interviews, photographs, measurements, police records, medical records, and event-data information when available. In an individual case, the available material may also include traffic-camera or business video, dash-camera footage, 911 records, phone or fleet data obtained lawfully, repair history, roadway design records, weather, and witness statements.
Each source has limits. A photograph records one view. A witness may not have seen the entire event. Event data records selected variables for a limited period and must be interpreted in the context of the specific vehicle. A police diagram may be preliminary. Sound analysis identifies those limits rather than hiding them.
Vehicle and scene inspection
Vehicle damage, tire marks, debris, fluid, gouges, final rest positions, sight distance, grades, curves, signals, and lane geometry may help explain movement and impact. Measurements should be tied to a documented method. If a vehicle may contain relevant physical or electronic evidence, inspection and preservation should be considered before repair, sale, salvage, or destruction.
What does an expert do?
A qualified reconstruction professional selects methods that fit the evidence and explains the assumptions used. The expert may calculate a range rather than one exact number. Medical or biomechanical questions can require a different specialist. The attorney's role is to identify the legal issue and build the admissible record; the expert's role is to offer opinions within the expert's actual field.
When is reconstruction useful?
Reconstruction may be useful when accounts conflict, a severe injury makes the sequence important, a commercial vehicle or multiple vehicles are involved, a roadway condition is disputed, or a product or safety system may have failed. It may be unnecessary when reliable video and uncontested evidence already answer the relevant question. The cost and scope should fit the matter.
Preserve before trying to recreate
The strongest reconstruction cannot restore evidence that was never kept. Record the tow and storage location, save photographs in their original form, keep repair estimates and insurance notices, identify cameras promptly, and preserve witness contact information. Do not alter a vehicle or component for testing without a controlled plan that accounts for the interests of all parties.
Reconstruction is most persuasive when another qualified person can understand the source material, methods, assumptions, and uncertainty. A vivid animation is not a substitute for that foundation.