The Role of Alcohol, Marijuana, and Other Drugs in the Accidents of Injured Drivers. Volume 1, Findings

NHTSA - Behavioral Safety Researchhttps://doi.org/10.21949/15251321982PDFResearch PaperTerhune, K. W.Calspan Field ServicesUnited States. National Highway Traffic Safety AdministrationUnited States. National Highway Traffic Safety AdministrationDrunk driversDrugged driversTraffic accidentsAlcoholsMarijuanaTranquilizersInjuriesAccident dataDOT-HS-806-199ZS-5769-V-1NTIS-PB83133074DOT-HS-5-01179Final reportUsing samples of blood obtained from 497 injured drivers at a Rochester, NY hospital, this study determined the incidence rates of alcohol, THC (marijuana agent), and other drugs. Accident data (police reports, driver interviews) were also collected, and analyses determined driver culpability rates, collision types, and crash circumstances involving alcohol and certain drugs. Main substances found were alcohol (25%), THC (10%) and tranquilizers (8%); 38% of the drivers had alcohol or some other drug tested for in their systems. Culpability rates were: 74% for intoxicated drivers, 53% for THC-only drivers, 34% for drugfree drivers, and 22% for tranquilizer-only drivers. Alcohol-involved crashes were predominantly single vehicle accidents, followed by striking vehicles in head-on and rearend impacts. No unique THC or tranquilizer collision types were found. Circumstances overrepresented in alcohol crashes were curves, occurrence on weekends, occurrence between midnight-6AM, unlighted streets, and non-intersection locations. "Alcohol accident types" were identified, e.g. single-driver crash occurring midnight-6AM on a curve (95% alcohol involvement). Police reporting of alcohol involvement was also analyzed. Possible roadway and vehicle countermeasures to reduce impaired-driver accidents were suggested. Other recommendations addressed police alcohol detection and NASS or FARS monitoring of alcohol involvement. Further study clarifying the crash roles of THC and tranquilizers in fatal and non-fatal crashes was considered essential. /Abstract from report summary page/129