Alcohol as a Cause of Traffic Crashes: Very Important Issue

Alcohol-related traffic crashes are not necessarily caused by alcohol. Many are, but no one knows the exact proportion. So what’s the role of alcohol as a cause of traffic crashes?

First, there’s very strong evidence of two important things.

  1. Alcohol adversely affects driving-related skills. That’s such things as vision, reaction time, judgment, and the ability to divide attention.
  2. Intoxication greatly decreases driving performance.

Crashers are Similar

It is also clear that drinking drivers who crash are similar in many ways to sober drivers who crash. Both groups are disproportionately

alcohol as a cause of traffic crashesYoung



Suffer from alcohol or drug problems

Characterized by aggression, hostility or other “undesirable” attitudes and personality traits.

Drunk drivers don’t become model drivers when sober. Even when completely sober, those who sometimes drive drunk are at high risk of being involved in traffic crashes. But there’s every reason to believe that alcohol frequently contributes to crashes.

Responsibility Analysis

alcohol as a cause of traffic crashesOne technique that demonstrates this is called responsibility analysis. Resarchers examine multiple-vehicle crash reports without knowing the drivers’ blood alcohol concentrations (BACs). Then they estimate the degree to which each driver was responsible for the crash.

In a sample of injured drivers, they estimated that 34-43% of sober drivers were responsible. That compared to 74-90% of intoxicated drivers.1

A large study examined 1,882 fatally injured drivers in several states. It concluded that 68% of sober drivers and 94% of intoxicated drivers were responsible for their crashes. The responsibility rates were higher in this study. That’s because it included single vehicle crashes. And drivers in single vehicle crashes are almost always deemed responsible. Nevertheless, the pattern is the same. That is, responsibility for accidents increases with intoxication.2

Important Question

How many drunk drivers would have had accidents if they were sober? Again, no one knows. But one expert, James Hedlund, has identified three broad types of drinking drivers, for whom the answer probably differs:

  1. “Normal” drivers who are social drinkers. Such drivers may miscalculate the effects of alcohol on their performance. Obviously alcohol increases their crash risk. Clearly, their crash rates would drop if they did not drive after drinking,
  2. “High-risk” drivers. These are drinkers for whom alcohol abuse may just be another form of risk-taking. Or may promote this behavior by lowering inhibitions. Abstaining might not reduce their crash rates much.
  3. Alcoholics, for whom alcohol abuse is an important part of life. Abstaining would require a complete lifestyle change. If they abstained, their crash rates should drop significantly.3

Groups Respond Differently

Dr. Hedlund says measures to limit drinking and driving effect the three groups differently.

  1. Arrest, fines, embarrassment, etc. tend to be effective in reducing violations by “normal” drinkers. Education may also be especially effective with this group. In fact, much of the reduction in alcohol-related crashes may come from this group.
  2. Arrest and punishment may have little effect on “high-risk” drivers. Some drivers may mature out of high-risk behaviors. However, high-risk drivers may be the hardest to change. That’s because the desire for high-risk may be so deeply rooted in their personality.
  3. Alcoholics are not likely to be effected by anything not dealing directly with their alcoholism. Therefore, they are most likely to be changed by DUI Courts.

The proportion of alcohol-involved traffic accidents that would have occurred even if the drivers had been sober remains unknown.

Resources: Alcohol as a Cause of Traffic Crashes


Drinking and Driving Facts and Solutions.  

Drinking and Driving. A Crash Course. eVideo. NY: Films Media, 2015.

Goodman, K. and Simon, K. Safe Road Home. Stop Your Teen from Drinking & Driving. NY: Sterling, 2005.

Kiesbye, S. Drunk Driving. Detroit: Greenhaven, 2011.

Mendralla, V. and Grosshandler, J. Drinking and Driving, Now What?  NY: Rosen, 2012.

Van Tuyl, C. Drunk Driving. Detroit: Greenhaven, 2006.


1. Terhune, K.W. and Fell, J.C. The Role of Alcohol, Marijuana, and Other Drugs in the Accidents of Injured Drivers. Washington, DC: National Highway Traffic Safety Administration (NHTSA), 1982.

2. Terhune, K.W. et al. The Incidence and Role of Drugs in Fatally Injured Drivers. Washington, DC: NHTSA, 1992.

3. Hedlund, J. “If they didn’t drink, would they crash anyway?” — The role of alcohol in traffic crashes. Alcohol, Drugs and Driving, 1994, 110(2), 115-125.

4. Ibid.