Engineer Discusses Methodologies for Reconstructing Head-On Collision

car crashPlaintiff was the passenger in a vehicle that was struck head-on by an SUV that crossed the double-yellow line on a curve. She suffered severe injuries, and the driver of her car was killed.

She sued the estate of the driver of her vehicle and the driver of the vehicle that crossed the line for negligence and the county for defective road design.

Question(s) For Expert Witness

  • 1. What were the road conditions?
  • 2. Did they meet safety standards?

Expert Witness Response

It is my opinion that the roadway geometry did not meet the required design standards for the posted 45 mph speed limit; sight distance was limited to 248 feet by an embankment off the northwest shoulder of the roadway; and the curve was deficient in sight distance for southbound vehicles because the measured sight distance of 248 feet is less than the distance required by design standards, which is 313 feet. This opinion is based on scientific evidence and testing. Specifically, the roadway geometry and available sight distance were evaluated using the geometric conditions existing at the time of the accident, which were measured using a total station (surveying instrument).

Current design standards were not cited in my report because they are not applicable. Design standards apply to new construction or reconstruction projects. For the posted 45 mph speed limit, current standards require even more sight distance than the 1965 policy.

The methodologies used to perform the accident reconstruction in this case are indicated in my report. Specifically, three different analyses were performed: (1) Conservation of Momentum analysis; (2) Conservation of Energy analysis; (3) simulation using SMAC algorithm (simulation model of automobile collisions). All of these methods are accepted techniques used in the fields of engineering and accident reconstruction, and all of them have been validated using staged collisions.

The expert is a professional engineer certified in accident reconstruction.


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