Accident reconstruction
In plain English: accident reconstruction is the scientific work of figuring out how a crash happened: speeds, positions, braking, timing and sight lines. It's done by engineers or specially trained police officers using physical evidence and physics.
When you might need one
Most car accident claims never need a reconstruction. Fault is obvious in a typical rear-end shunt. It becomes worth considering when the story is disputed and the stakes are high:
- Both drivers say the light was green.
- A pedestrian or cyclist is seriously hurt and the driver says they "came out of nowhere".
- A truck, bus or commercial vehicle is involved.
- There are no independent witnesses.
- Someone has died or suffered a life-changing injury.
What reconstructionists work from
They piece together skid and yaw marks, debris fields, final resting positions, crush damage to each vehicle, road layout, signal timings and weather. Increasingly the best evidence is digital: event data recorder downloads, dashcam footage, CCTV and phone data. From these they calculate things like speed at impact, stopping distance and whether a driver had time to react.
Police reconstructions
After serious or fatal collisions, police often send their own collision investigators. In the UK these are forensic collision investigation units. In the US and Canada, larger police services have similar teams. Their reports can be very valuable, but they may not be released until any criminal investigation ends. Your lawyer can request them when available.
Speed matters more than anything
Scene marks fade within days. Vehicles get repaired or crushed. Video is often overwritten within weeks. If fault is likely to be disputed, a lawyer can send a preservation letter and arrange for an expert to inspect the vehicles before they're gone.
A motorcyclist is hit by a car turning right. The driver says the bike was speeding. A reconstructionist uses CCTV frame timing from a nearby shop and the crush depth on the car to estimate the motorcycle was close to the speed limit, and that the driver turned when the bike was already too close to stop.
Cost and value
Reconstruction reports can be expensive. In a smaller claim, the cost may outweigh the benefit. Your lawyer should weigh it against what's at stake and whether the other side is likely to use its own expert.
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Related terms
General information, not legal or medical advice. Rules differ between US states, the UK and Canadian provinces, so check the law where your accident happened. How we write and check · Legal disclaimer