Toxicology – Tractor Trailer


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.