Will new car technology stop people from driving drunk?

A federal agency that regulates vehicle safety features took the first steps this week to require technology in cars and light trucks that would automatically prevent drunk drivers from starting their vehicles.

The announcement from the National Highway Traffic Safety Administration won’t lead to changes in cars in the next few years, mainly because the technology that the agency wants to deploy is still under development. But it reflects a growing concern in Congress—which told NHTSA to explore the technology—and in the states, over the lack of progress in recent years in deterring intoxicated people from driving.

“It is tragic that drunk driving crashes are one of the leading causes of roadway fatalities in this country and far too many lives are lost,” said Polly Trottenberg, the deputy secretary of the U.S. Department of Transportation in a statement. “The Advance Notice of Proposed Rulemaking we are announcing today is the first step toward a new safety standard requiring alcohol-impaired-driving prevention technology in new passenger vehicles.”

Alcohol use remains one of the biggest factors in fatal traffic crashes, along with speeding and lack of seatbelt use. It is a factor in 31% of all traffic deaths, according to NHTSA. More than 13,000 people died in drunk driving crashes in 2021, the last year for which federal data is available. That amounts to one person dying every 39 minutes.

“Concerted efforts by NHTSA, states and other partners to implement proven strategies generated significant reductions in alcohol-impaired driving fatalities since the 1970s when NHTSA records began; but progress has stalled,” the agency wrote in its notice.

Every state in the country has at least made it a crime to drive with a blood alcohol concentration, or BAC, of 0.08% or higher. Utah is the only state that has set a lower threshold at 0.05%. Its unique approach has shown promise in lowering drunk driving deaths, but other states have been reluctant to follow its lead. People convicted of drunk driving are also required to use an alcohol interlock in most states to prevent them from using their vehicles while intoxicated.

But the approach outlined by NHTSA in its 99-page notice Tuesday would be slightly different. In the 2021 infrastructure law, Congress instructed the agency to require “advanced drunk and impaired driving prevention technology” by 2024 if the technology could passively and accurately determine if a driver was impaired.

The agency said it is exploring options to do so, but the technology doesn’t appear to be ready for widespread use yet. “Several technologies show promise for detecting various states of impairment, which for the purposes of this notice are alcohol, drowsiness and distraction,” it noted. “However, technological challenges, such as distinguishing between different impairment states, avoiding false positives, and determining appropriate prevention countermeasures, remain.”

Still, Jonathan Adkins, the CEO of the Governors Highway Safety Association (GHSA), which represents state traffic safety agencies, said exploring those technologies could have a big impact.

“Of the many critical safety provisions of the [2021 infrastructure law], this requirement for alcohol detection technology has the potential to save the most lives on our roads,” he said in a statement. The notice “is overdue, cannot be finalized soon enough and should remain a top roadway safety priority.”

As NHTSA noted, its focus with developing new technologies also includes exploring options to reduce drowsy driving and distracted driving. The size of the safety problem for distracted driving in particular is “immense,” NHTSA explained.

The agency left open the details of how the detection systems would work, but said the same technologies could be used to monitor alcohol intoxication, drowsy driving and distracted driving. One possibility would be a touch pad with sensors that use infrared light to collect information about the chemical properties of a user’s skin, including the concentration of alcohol present. That touch pad could be embedded in something the driver would otherwise have to touch, like an ignition switch, steering wheel or gear shift selector.

The cars would likely use the 0.08% threshold for blood alcohol content that the federal government has set as a standard for states. But NHTSA cautioned that alcohol can play a factor in fatal crashes at even lower levels.

Another option would be breath detectors that could analyze naturally exhaled air to determine the blood alcohol content of the driver’s breath, although current systems are not “passive” as required by the infrastructure law, because they require users to actively breathe onto a sensor.

“Nearly two-thirds of all alcohol-impaired fatalities involve high blood alcohol levels with a BAC level at or greater than 0.15%,” the agency explained. “Yet even a small amount of alcohol can affect an individual’s driving ability. In 2020, there were 2,041 people killed in alcohol-related crashes where a driver had a BAC level of .01 to .07.”

So instead of relying on BAC, the agency could determine intoxication by measuring vehicle or driver movements to determine if the driver is impaired by alcohol, distracted or drowsy. The vehicles could determine whether the driver’s eyes are looking forward at the road and whether their hands are on the steering wheel. Those systems can also monitor whether the driver is taking appropriate steering, braking or accelerating action.

But some problems remain with that method because drivers can show different signs of impairment from one another and because drowsy drivers are sometimes falsely identified as being impaired by alcohol.

The infrastructure law does allow NHTSA to use a combination of detection systems.

The agency also noted that many automakers—including Hyundai, Nissan, Toyota and Volvo—have already started developing technologies that could immobilize a car if a driver was too drunk to operate it safely.