Alcohol, Other Drug Use Including Cannabis, and Speeding

Evelyn Vingilis, Ph.D.

Bio

Dr. Vingilis is Professor Emerita and Adjunct Research Professor with the Department of Family Medicine in the Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada. She was formerly Head of the Drinking Driving Research Programme and the Risk Factors Programme at the Addiction Research Foundation. Her two main research programs are injury, prevention and control, and mental health and substance use with a particular focus on at-risk youth. She has methodological expertise in program and policy evaluation, and questionnaire development and survey design.

In 2010, she received the Widmark Award, “the highest honour bestowed by the International Council on Alcohol, Drugs and Traffic Safety (ICADTS) to individuals who have made outstanding, sustained, and meritorious contributions”. In 2018, she received the Lifetime Achievement Award from the Canadian Association of Road Safety Professionals.

Abstract

In Canada, two major contributors to motor vehicle fatalities are driving under the influence of alcohol and other drugs, and speeding. Yet, little is known about the effects of both driving under the influence of alcohol, other drugs, and speeding. The following article presents what we know about driving under the influence of alcohol, other drugs, including cannabis, or speeding in relation to, 1) collision casualties, 2) roadside and other surveys, 3) effects in simulator studies, and 4) the extremely limited available research on the association between both driving under the influence, and speeding. 

Canadian prevalence of alcohol- and other drug-related collision casualties

According to a 2023 Traffic Injury Research Foundation (TIRF) report, the percentage of alcohol-related fatalities in Canada in 2020 were 29.0 percent compared to 30.0 percent in 2000, while the percentage of drug-related fatalities in 2020 were 37.1 percent compared to 10.7 percent in 2000 (Brown et al., 2023). “Drugs” defined by TIRF included cannabis, illicit, prescription, and over-the counter drugs, which were based on “toxicological data from the coroner or medical examiner, police-reported collision data, and coroner/medical examiner narrative information” (Brown et al., 2023). When fatally injured drivers were examined, the percentage who tested positive for cannabis in 2020 were 30.1 percent, making cannabis the most commonly found drug excluding alcohol (Brown et al., 2023). 

Beirness et al. (2021) examined prevalence of alcohol, cannabis and other drugs through toxicological tests in 921 driver motor vehicle fatalities in Ontario between January 2016 and December 2018. This sample represented 86.7% of all drivers who died in collisions during this period in Ontario. Of the sample, 26.1 percent tested positive for alcohol, and 27.3 percent tested positive for cannabis, while 53.7 percent tested positive for alcohol and/or other drugs, including cannabis. The Ontario Road Safety Annual Report (ORSAR) (2021) reported that in 2021, 17 percent of all Ontario fatalities were categorized as drinking and driving, and 15 percent were categorized as drug use and driving. 

Findings are similar for non-fatally injured drivers. Historically, among drugs other than alcohol, cannabis has been the most commonly found drug among non-fatally injured drivers presenting to emergency departments (EDs). As far back as the 1980’s, Vingilis and her research team conducted the first prospective study on prevalence of alcohol and other drugs among injured drivers consecutively admitted to an Ontario regional trauma centre. They found that alcohol was present in 18.0 percent of injured drivers while cannabis was present in 13.9 percent of injured drivers (Stoduto et al., 1993). As well, 16.5 percent of the injured drivers were positive for alcohol in combination with one or more other drugs, including cannabis, illicit, prescription, and over-the counter drugs. 

Subsequent Canadian studies have shown similar findings. For example, Brubacher et al. (2016) found alcohol in 17.8 percent of non-fatally injured drivers presenting to EDs at seven participating British Columbia trauma centres, with cannabis metabolites identified as the second most common recreational drug at 12.6 percent, and detected Δ-9-tetrahydrocannabinol (Δ-9-THC), the psychoactive substance of cannabis, at 7.3 percent of drivers. A recent study of cannabis and alcohol use was conducted on non-fatally injured drivers and passengers presenting to the ED of a participating hospital in British Columbia or Ontario between August 2020 and March 2024; alcohol was present in 14.2 percent of drivers, THC was present in 12.4 percent, and 3.2 percent were positive for both alcohol and cannabis (Pei et al., 2025). 

Canadian prevalence of speed-related collision casualties

 

For speeding, the percentage of speed-related fatalities in Canada were 30.3 percent in 2020 compared to 22.3 percent in 2000 (Brown et al., 2023). The Ontario Road Safety Annual Report (ORSAR) (2021), reported that 23 percent of all Ontario fatalities in 2021 were categorized as speed-related. Yet, these percentages of driving under the influence or speeding casualties are not mutually inclusive, meaning that some casualties include any combination of alcohol, other drugs, notably cannabis, and speeding. 

Unfortunately, despite the fact that in Canada driving under the influence and speeding are major risk factors for motor vehicle collisions, the overwhelming majority of research and databases examining these risky driving behaviours have recorded and reported on them individually, not in relation to each other (Johnson, 2025). Alcohol, other drugs (such as cannabis), and speeding have been considered distinct causes of motor vehicle collisions (Johnson, 2025). Moreover, they are assumed to be caused by different factors, despite that fact that drivers under the influence of alcohol and/or other drugs, and excessive speeders, share similar characteristics such as being younger, male, and unbelted (Johnson, 2025). As well, there is evidence from motor vehicle fatality databases that, for example, fatally injured drivers with higher blood alcohol concentrations (BACs) drove faster than sober drivers and that fatally injured speeders were more likely to have BACs greater than 0.08 g/dl than non-speeders in fatal collisions (Johnson, 2025). However, associations among driving under the influence, speeding, and increased collision risk could be confounded by other factors, such as risk-taking propensity (e.g., Bergeron & Paquette, 2014). Unfortunately, this paucity of research on the relationship between driving under the influence and speeding means a limited understanding of the interactions and their complexities.

Canadian survey studies on prevalence of alcohol and other drug use and driving

Survey studies from Canada have examined the prevalence of alcohol, cannabis, and other drug use and driving. For example, roadside surveys were conducted in five regions of Canada (British Columbia, Manitoba, Ontario, Yukon, and Northwest Territories) on drivers randomly sampled from traffic streams at pre-determined locations during Wednesday to Saturday evening hours of 21:00 and 03:00 before the legalization of cannabis (Canadian Council of Motor Transport Administrators, 2019). Of the surveyed drivers, 4.4 percent of were positive for alcohol, and 0.7 percent had BACs over 80 mg/dL; 10.2 percent tested positive for drugs, and 7.6 percent tested positive for cannabis. A total of 12.9 percent of drivers were positive for alcohol and/or drugs. Thus, less than 15 percent of sampled drivers tested positive for alcohol, drugs or both. These findings point to the overrepresentation of alcohol- and drug-using drivers in motor vehicle collision casualties. 

Canadian survey studies on prevalence of speeding

Unlike driving under the influence, speeding is a common driving activity in Canada.  A Transport Canada survey conducted by Ekos Research Associates (2007) found that 58 percent of surveyed drivers reported frequently speeding on highways, while 39 percent reported frequently speeding on two lane highways and country roads; 13 percent reported frequently speeding in residential areas. A population-based Ontario survey of 1595 drivers conducted during the COVID-19 pandemic found that 65.2 percent of respondents reported speeding with 7.2 percent reporting speeding somewhat or much more since the start of the pandemic (Vingilis et al., 2024). A recent poll of 2,880 Canadians conducted by the Canadian Automobile Association (CAA) from September 13 to 21, 2024 reported nearly 70 percent reported speeding in residential areas at least once in the past year, about 50 percent reported speeding regularly on highways, while about 20 percent reported regularly driving “well over the speed limit” (CAA, 2024). These findings suggest that the majority of Canadians engage in speeding. Thus, although speeders have a higher risk of collision involvement (e.g., Vingilis et al., 2024), speeders, as a group, may not be over-represented as drivers in motor vehicle collision fatalities.

Effects of alcohol and cannabis on speeding

A few studies have examined the effects of alcohol and cannabis on speeding. For example, some simulator studies examining the effects of different blood alcohol concentrations (BACs) on driving performance, such as speeding, have found that drivers with higher BACs drove at faster speeds than sober drivers (e.g., Yadev & Valega, 2020). However, other simulator studies suggest a more complex relationship between driving under the influence of alcohol, and speeding, with factors, such as fatigue affecting outcomes (Christoforou et al., 2012). Nuanced findings have also been found for cannabis use and speeding. For example, Dahlgren et al. (2020), in a driving simulator study, examined the effect of cannabis use on driving performance, including speeding, in non-intoxicated, heavy, recreational cannabis users and healthy controls with no history of cannabis use. The results indicated that chronic cannabis use was related to impaired driving performance, such as increased speeding, independent of acute intoxication. When early onset cannabis users were compared to late onset cannabis users, impairment was primarily found in the early onset group. However, when self-reported impulsivity was controlled for, most significant between-group differences were no longer significant, suggesting that increased impulsivity within the cannabis users affect performance differences found on the driving simulator. Thus, relationships are commonly found for driving under the influence of alcohol or cannabis and speeding, although other factors may be confounding the effects. 

Alcohol, cannabis, other drugs, and speeding among motor vehicle casualties

Very few studies have examined collisions that were alcohol- and/or drug- related, and speeding-related. A Norwegian study examined fatal collision data on a sample of drivers analyzed for alcohol, and legal and illegal psychoactive drugs, including cannabis (Bogstrand et al., 2015). Of the fatally injured drivers impaired by alcohol (BAC >0.5 g/L) and/or drugs (concentrations corresponding to the 0.5 g/L limits according to the Norwegian Road Traffic Act), 71.7 percent were speeding when the collision occurred, while 33.2 percent of the sober drivers were speeding. Of fatally injured drivers impaired only with alcohol or cannabis, 80.3 percent and 71.4 percent, respectively, were speeding when the collision occurred. These motor vehicle collision fatality data findings suggest a large percentage of impaired drivers were also speeding at the time of their fatal collision. 

A recent US study examined driving under the influence and speeding using collision data. Johnson (2025) used National Highway Traffic Safety Administration 2019–2021 collision data to assess whether speeding could account for some of the collision risk related to driving under the influence of alcohol. The statistical analysis identified a statistically significant BAC × Injury Severity interaction, meaning that drivers with higher BACs drove at higher speeds than sober drivers and this result was exacerbated for more severe injuries (Johnson, 2025). Of the fatally injured drivers, those with BACs of 0.16 g/dl were driving more than 10 mph faster than sober drivers. Johnson (2025) estimated the collision risk related to speed with the collision risk related to BAC levels: “at 0.08 g/dl, higher speeds accounted for nearly 50% of the fatality crash risk attributed to alcohol, and 25% of the fatality crash risk at 0.16 g/dl. For serious injuries, estimates were 39% and 16%, respectively” (p. 755).

A road-side study also examined the association between driving under the influence, and speeding. A road-side survey was conducted in Norway to examine the relationship between self-reported road traffic collisions, and recent use of alcohol and other drugs, and self-reported speeding in the last two years (Jørgenrud et al., 2018). Over 5000 drivers were stopped; 0.3 percent tested positively for alcohol, while 1.4 percent tested positively for cannabis. Neither testing positive for alcohol nor positive for cannabis was associated with a reported speeding ticket in the previous two years. However, testing positive for cannabis was associated with a collision in the previous two years. These limited driver casualty studies suggest a strong association between driving under the influence of alcohol or cannabis, and speeding, while the road-side survey study suggests no relationship between testing positive for alcohol or cannabis and self-reported speeding tickets. Unfortunately, no published Canadian collision casualty research has been found that examined the association between driving under the influence and speeding to provide information on the Canadian context.

Are Canadian drivers who drive under the influence of alcohol, and/or cannabis, and speeders from the same population? 

Our Ontario driver survey conducted in 2021 during the COVID-19 pandemic did examine the following self-reported driving behaviours: driving after having two or more drinks of alcohol in the previous hour; driving within two hours of using cannabis; driving within two hours after having two or more drinks of alcohol and using cannabis; speeding (at least 15 km/hr over the speed limit); and street racing (e.g., 50 km/hr or more over the posted speed limit; driving contest). Significant but weak correlations were found between self-reported speeding and driving after having two or more drinks of alcohol in the previous hour (r = 0.23), driving within two hours of using cannabis (r = 0.21), and driving within two hours after having two or more drinks of alcohol and using cannabis (r = 0.19) (Unpublished data). However, significant and strong correlations were found between self-reported street racing and driving after having two or more drinks of alcohol in the previous hour (r = 0.79), driving within two hours of using cannabis (r = 0.83), and driving within two hours after having two or more drinks of alcohol and using cannabis (r = 0.82) (Unpublished data). Previous survey research from the Centre for Addiction and Mental Health (CAMH) Monitor, an ongoing cross-sectional telephone survey of adults in Ontario, examined the relationship between street racing and driving after using alcohol or cannabis; speeding was not examined (Wickens et al., 2017). A significantly higher percentage of those who reported street racing reported driving after drinking, and driving after cannabis use (Wickens et al., 2017). These findings would suggest weak relationships between driving under the influence and speeding but strong relationships between driving under the influence and a more extreme, high- risk form of speeding, i.e., street racing.

Unfortunately, in Canada speeding is normative, while driving under the influence of alcohol and/or other drugs are not. Similarly, street racing is not normative; our Ontario driver survey conducted during COVID-19 found that 15.4 percent reported engaging in street racing (Vingilis et al., in preparation). These findings could suggest more complex relationships between driving under the influence and speeding. Brown et al. (2016) examined distinct characteristics of drivers engaging in different forms of risky driving that may provide a more nuanced understanding of drivers. Four groups were compared on a range of psychosocial, behavioural, personality and neurobiological assessments: 1) drivers with one or more driving while impaired (DWI) convictions; 2) non-alcohol reckless drivers (SPEED); 3) drivers with a profile of DWI convictions and moving violations (MIXED); and 4) low-risk controls (CTL) (Brown et al., 2016). Two perspectives were considered: one in which risky drivers were presumed to engage in a range of risky behaviours with common antecedents (e.g., Problem Behaviour Theory) and another in which risky drivers were seen to be in different subgroups that shared unique characteristics and pathways (Brown et al., 2016). Results showed distinct characteristics among the three risky driving groups. Both the DWI and MIXED groups showed greater alcohol misuse compared to the SPEED and CTL groups with the DWI group exhibiting the greatest alcohol misuse severity, although the lowest risk level when sober (Brown et al., 2016). The MIXED group demonstrated more substance misuse, sensation-seeking, antisocial and reward sensitive personality characteristics (Brown et al., 2016). The SPEED group presented with greater disinhibition, disadvantageous decision-making, sensation seeking, and risk taking (Brown et al., 2016). Reflecting on these different typologies and on the Interactionist Approach to risky driving behaviours, which reflects on impulsive, compulsive and instrumental risky driving in relation to different situational contexts (Vingilis & Mann, 1986), one could speculate that those who drive under the influence of alcohol, and/or other drugs and/or speed could also fall under different subtypes. Certainly, a greater percentage of men and younger drivers report speeding more, and driving under the influence of alcohol and cannabis more. However, Canadian research has found that the majority of drivers report speeding but only the minority report engaging in driving under the influence. These findings indicate that speeding is normative but driving under the influence is not. 

To sum, the dearth of research examining driving under the influence of alcohol, and other drugs, and speeding makes it difficult to provide a comprehensive understanding of the relationship. The limited epidemiological and experimental research on the topic of driving under the influence and speeding is odd, given their major contributions to motor vehicle collisions. Brown and colleagues’ (2016) research on different risky driving behaviours sets the stage for future exploration on the complexities of the relationships between driving under the influence and speeding on driving performance and collision risks. Their research would suggest that a better understanding of risky driving and potential subtypes could provide more tailored intervention strategies.

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