Impaired Driving Remains a Top Priority for NTSB

End Substance Impairment in Transportation


Download the issue Fact Sheet
What is the issue?
The issue is something you might not realize is happening: The world around you seems to move slower. Your concentration lags. When your brain tells your hand to move, it takes longer for your hand to respond and the movement is clumsy. When you blink, your eyelids stay closed longer. You are feeling the effects of the alcohol you drank earlier, and you are driving a car. But you probably don’t even recognize how impaired you are – or the risk that you pose to yourself and others.

This scenario is all too common. In a 2013 AAA Foundation for Traffic Safety survey, 13 percent of drivers said they thought that they had driven close to or over the legal blood alcohol concentration (BAC) limit in the previous year. According to the Centers for Disease Control and Prevention, drivers make about 112 million alcohol impaired trips each year.

According to the National Highway Traffic Safety Administration, the proportion of fatally injured drivers who had drugs in their system rose from 13 percent to 18 percent from 2005-2009. In 2012, 10.3 million people reported driving under the influence of illicit drugs in the past year.

Since 2000, almost 160,000 people have died in motor vehicle crashes involving impaired drivers. And the problem of impairment is not limited to highways.

The NTSB recently studied drug use among fatally injured pilots. The prevalence of potentially impairing drugs increased from an average of 11 percent of fatally-injured accident pilots during the period from 1990-1997 to an average of 23 percent of accident pilots during the period 2008-2012. During the same time periods, positive marijuana results increased from 1.6 percent to 3.0 percent. But the most commonly found impairing substance in fatal crashes was diphenhydramine, a sedating antihistamine found in over-the-counter medications.

Time after time, NTSB investigations have found substance impairment as a cause or a contributing factor in transportation accidents. Complex machinery such as cars, planes, trains, ships, and pipelines require operators to be at their best – not impaired by alcohol or drugs.

Finally, nobody really knows the effect that decriminalizing marijuana will have on transportation safety.

What can be done?
We need more and better data to understand the scope of the problem and the effectiveness of countermeasures. In commercial transportation industries, operators and enforcement authorities must not neglect required post-accident testing. Additionally, states should increase collection, documentation and reporting of driver BAC test results following crashes.

Drivers and other transportation operators need good information to make informed decisions. While many recognize the impairment potential of illicit drugs, they may not appreciate the potentially impairing effects of prescribed or over-the-counter medications, especially in combinations. Discuss your transportation activities with your doctor before taking a medication, and discuss the impairing effect of any medical condition as it might increase your risk of having an accident. Treatment should not always exclude you from operating a vehicle, but such conditions and medications need to be monitored. If any medication label warns against operating heavy machinery, that includes vehicles. Also, while the danger of drinking and driving is more broadly understood than that of driving under the influence of drugs, many do not know that even low levels of alcohol can degrade skills and increase crash risk.

Additional countermeasures include stronger impaired driving laws, increased use of high-visibility enforcement, expanded use of existing technology such as ignition interlocks and passive alcohol sensors, development of emerging in-vehicle technology such as the Driver Alcohol Detection System for Safety, and targeted measures for repeat offenders such as the use of DWI Courts.