An SUV was broadsided by an oncoming postal truck at a residential neighborhood intersection. There were no witnesses to the accident other than the two drivers who related drastically different accounts of the events leading up to the collision. Edison Engineering was called in to determine if either driver was telling the truth.

Our investigation consisted of three primary components. First, we analyzed the data at-hand. The SUV had been destroyed, the truck had been repaired, and the vehicle’s point of impact and rest positions had not been measured, making the limited photos of the accident scene extremely important. During a visit to the accident scene, those images were utilized to reconstruct the positions of the vehicles at impact and at rest, the tire marks and gouges left on the roadway by the vehicles after they collided, and the sight lines available to each driver.

Second, where information was ambiguous or missing, we performed testing. This included full-scale laboratory measurement of the truck’s yaw moment of inertia, a key parameter since the truck rotated 90 degrees after impact.

Finally, armed with the most accurate data possible, we performed detailed computer simulations of the accident as well as other accident analysis calculations. The results were unambiguous, completely supporting the truck driver’s story that the SUV was traveling at high speed and did not obey the intersection’s stop sign.


  • Photogrammetry
  • Testing & measurement
  • Human factors analysis