A SIMULATOR STUDY OF THE COMBINED EFFECTS OF ALCOHOL AND MARIHUANA ON DRIVING BEHAVIOR. PHASE I

The study described in this report investigated the effects of alcohol and marihuana, alone and in combination, on driver performance and behavior in a fully interactive driving simulator. The simulator provided the driver a complex visual scene similar to a rural nighttime drive, and allowed the driver full control of steering and speed maneuvers. Performance and behavior data were collected during a 10-12 mile drive requiring about 15 minutes to complete. A variety of events were encountered during the drive, including curves, obstacles in the roadway, and winding roads. Accidents, tickets, and speed were recorded as traffic safety measures during the overall drive. Driver behavior, speed control, and steering performance were collected during each event to provide insight into the impairment mechanisms of alcohol and/or marihuana on the driver. A full placebo experimental design was employed which included all combinations of 3 marihuana (0, 100, and 200 microg Delta-9 THC/kg body weight) and 2 alcohol (0 and 0.10 percent BAC) levels. Based on a large number of driver performance and behavior variables, alcohol was found to have a pervasive and significant impairing effect. Simulator accidents increased reliably under alcohol, which was accounted for by increased steering and speed control variability. Marihuana effects were minimal, the primary one being speed reduction. This speed reduction, while statistically reliable, was minimal in terms of actual driving behavior and is probably of no practical significance. A significant drug interaction effect was observed in simulator accidents; however, the data do not allow us to identify the impairment mechanism leading to this result.

• Corporate Authors:

  Systems Technology, Incorporated

  13766 South Hawthorne Boulevard
  Hawthorne, CA  United States  90250

  National Highway Traffic Safety Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Stein, A C
  • Allen, R W
  • Cook, M L
  • Karl, R L
• Publication Date: 1983-2

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 86 p.

Subject/Index Terms

• TRT Terms: Alcoholic beverages; Behavior; Blood alcohol levels; Driver performance; Drivers; Driving simulators; Impaired drivers; Marijuana; Personnel performance; Speed control; Steering
• Old TRIS Terms: Driver impairment
• Subject Areas: Highways; Safety and Human Factors; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 00396131
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: TR-1066-2 Final Rpt., HS-806 414
• Contract Numbers: DOT-HS-5-01257
• Files: HSL, TRIS, USDOT
• Created Date: Aug 31 1985 12:00AM