Drugs and driving: Recent results from TIRF's Road Safety Monitor

From Issue: 
Vol LI, No. 2, May 2007

An extensive body of research has clearly established that alcohol use by drivers can severely increase the risk of collisions. An equally impressive body of literature has tracked changes in the magnitude of the problem over the past two and a half decades and shown that alcohol use by drivers has declined, along with the presence of alcohol in serious collisions. By contrast, much less is known about the contribution of drug- impaired driving to serious collisions or about the magnitude of drug use by drivers. Accordingly, any new information on the subject is welcomed. In this context, the TIRF Road Safety Monitor contained a number of relevant questions that addressed this issue.

The Road Safety Monitor is a public opinion survey developed and managed by the Traffic Injury Research Foundation (TIRF) to take the pulse of the nation on key road safety issues. Conducted annually since 2001, the survey examines:

  • what Canadians see as priority road safety issues and how concerned they are about them;
  • their views about how to deal with these problems;
  • what they know and don't know about safe driving practices; and,
  • how they behave on the highways.

The TIRF Road Safety Monitor includes a core set of questions that are asked each year to provide information on trends in attitudes, opinions and behaviours with respect to a variety of road safety issues, including drinking and driving. This is supplemented by a set of questions that probe more deeply into special, topical, and emerging issues. The fifth edition of the TIRF Road Safety Monitor contained a set of items about drugs and driving. The survey was administered by telephone to a random sample of Canadian drivers in September 2005. A total of 1,218 drivers completed the interview.

Results from the Road Safety Monitor show that the public is concerned about the issue of drugs and driving. In particular, 87 percent of Canadians think the problem of young drivers impaired by alcohol or drugs is a very serious or extremely serious problem; 61 percent consider the issue of older drivers impaired by prescription medication to be a very serious or extremely serious problem.

The survey found, consistent with other studies, that driving after marijuana/hashish use is not that common. Some 2.4 percent of survey respondents admitted to driving after using marijuana/hashish in the past year. Although this represents a very small proportion of drivers, when applied to the entire population of licensed drivers, this suggests that an estimated half-million Canadians admit to driving after using marijuana/hashish at least once in the past 12 months. In these terms, the behaviour is far less uncommon. Moreover, this represents a significant increase in the frequency of marijuana/hashish use and driving over the past three years.

Also consistent with previous research, the survey found a high co-occurrence of alcohol use and marijuana/hashish use. Sixty nine percent of those who reported driving after using marijuana/hashish also reported driving within two hours of drinking. The co- occurrence of these two substances increases the risk of collision considerably and is a reason for concern.

Drivers who admitted to using marijuana/hashish were found to differ from non-users in several ways. Users were younger, more likely to be male, unmarried and live in urban areas. They were also more likely than non-users to take risks when driving just for fun, and more likely to speed; they were more likely to have received a traffic ticket, and more likely to have been involved in a collision. Finally, and not surprisingly, they were far less supportive of enforcement initiatives that would help police detect drivers who have been using drugs.

“The Road Safety Monitor: Drugs and Driving,” report was written by Ward Vanlaar, Herb Simpson, Deanna Singhai and Dan Mayhew. Please visit: www.trafficinjuryresearch.com.