A tractor-trailer operator crashed into a work zone where several disabled construction vehicles were beyond the fog line and off the roadway. Subsequent urine testing of the tractor-trailer operator showed a positive result for d-Methamphetamine. Subsequent blood tests and hair tests were negative.

Introtech Accident Reconstruction Services

Introtech was asked to evaluate the toxicology test results to confirm impairment because of d-Methamphetamine. Introtech was also retained to conduct an accident reconstruction analysis of the tractor-trailer operator’s physical driving behavior and its potential association with d-Methamphetamine impairment. Introtech reviewed the police report, hospital records, chain-of-custody documents, laboratory test results. Introtech also visited the accident scene and the tractor-trailer vehicle, at which time the roadway and vehicle were digitally mapped, photographed, and subsequently evaluated via simulations produced in FARO REALITY.


  • The tractor-trailer operator was most likely impaired at the time of this crash. His physical driving behavior was consistent with the impairing effects of d-Methamphetamine.
  • The negative blood test was due to sample dilution.
  • The negative hair test was actually positive, but the drug concentration result registered just slightly under the laboratory’s cutoff concentrations for analysis.
  • The tractor-trailer operator was operating his motor vehicle with excessive speed.
  • The tractor-trailer operator did not perceive and react in time to avoid the crash.

To learn more about Introtech’s forensic toxicology process, learn more on our specific forensic toxicology page.