Booze and belts: New tech could handle a spike in highway deaths

Something historic, unprecedented and surprising happened in 2020. No, not that: A marked increase in highway fatalities attributed to drunk driving and reduced seat belt usage. The preliminary 2020 numbers are out and they aren’t good: We drove 13% less in 2020 than to 2019 yet total fatalities went up 7% year over year to 38,680, a setback of roughly a decade’s worth of progress. Here are two major new technologies that may arrive just in time to not only bend the curve back but maybe increase the pace of highway fatality reduction.

Alcohol interlocks for all?

If we could build cars that elegantly prevent operation by a drunk driver, why wouldn’t we? That’s an era we may soon enter thanks to a lesser-known provision of the $1.2 trillion Bipartisan Infrastructure Framework bill. It would require that we hit these milestones:

  • Within three years, regulators must set safety standards for universal alcohol detection tech in new cars sold in the US. 
  • Two years after that, automakers would have to develop the technology for deployment.
  • No longer than 10 years later, all new cars sold in the US must have alcohol interlock technology.

“Elegantly prevent” is the key to success here: Technology that looks nothing like the clunky, stigmatizing interlocks that courts typically mandate for serious DUI offenders. I recently took a look at some of the more elegant technologies that are out there, and they are many.

Cooley blows into alcohol interlock

Here’s what isn’t coming: The kind of interlock that courts mandate. These are too clunky, invasive to use, and stigma-inducing.


A coalition of major automakers called the Automotive Coalition for Traffic Safety in conjunction with a federal program called DADDSS — or Drive Alcohol Detection System for Safety — has just announced that a passive alcohol interlock system will be ready for installation on commercial vehicles later this year under an open-source license. It requires the driver blow a puff of air toward a sensor in the cabin that’s calibrated at a zero blood alcohol level. 

It will be 2024 before a version is ready for personal vehicles due to two challenging technical changes: Dispensing with the need to blow into a sensor and allowing calibration at 0.08 blood alcohol level (or whatever other level might be in force in a given jurisdiction). Both of those nuances make the device harder to engineer but automakers won’t foist them on the car-buying public until they’re ready. 

Seat belt interlocks return?

We’ve heard about increased risk-taking during the pandemic and that may explain reduced seat belt use in 2020: More than half of the people who died in a car accident that year weren’t belted in and succumbed to either impact injuries inside the car or from being ejected.

You may not know that all new 1974 model year cars sold in the US had an interlock that required the occupant of any front seat  position fasten their belt before the car would start. Motorist outrage was huge due to a sense of nanny state intrusion and the unreliability of a technology that could be fooled by something like an unbelted grocery bag on the front seat. It remains one of the few automotive safety laws ever rescinded by Congress.

1974 Chrysler seal belt interlock logic

Even Chrysler repair technicians needed an animated tutorial on the tortured logic of the 1974 seat belt ignition interlock in their company’s cars.


Today’s car buyers have a different view of safety, expressing satisfaction with new car technology that focuses on it, according to recent surveys by JD Power. That could mean the stage is set for the return of the seat belt interlock if it’s done right. 

GM is already on it: Little-noticed as the pandemic closed in was GM’s 2020 introduction of Buckle to Drive technology. It’s more nuanced than the old ’70s interlocks, which disabled the car. Buckle to Drive will allow a car to start and run, but not shift into Drive for up to 20 annoying seconds if you’re not belted. The technology has to be switched on as part of Teen Driver Mode, rather than being active at all times, but it sets the stage for more comprehensive technology that might come.  

Another tack is the graduated seat belt warning chime on late-model Subarus. The chime increases in volume the faster the car goes when occupants aren’t belted in.

Subaru seatbelt warning chimes

Seat belt chimes aren’t simple any more: Subaru’s latest ones have an escalating scale that alert you more urgently as the vehicle speed increases.


Building on these efforts, future seat belt interlocks could trade on any number of carrots and sticks, like limiting the speed a car can be driven and disabling the audio system or Bluetooth connections. They could also make verbal requests to buckle up, which are perhaps harder to ignore than a generic chime. Occupant sensing has come a long way as well, with modern airbag sensors already providing data about who’s seated where and what they weigh. In the offing are even more sophisticated cabin-monitoring technologies, which promise to make both seat belt compliance and drunk driving prevention more surgical.

Even if fatalities hadn’t recently spiked, these technologies seem inevitable. Air bags, electronic stability control, anti lock brakes and automatic emergency braking have done their part, yet fatalities stubbornly linger in the 30,000s per year. The next big drop in highway fatalities will almost certainly come from electronic enforcement of seatbelt use and sober driving.

Katherine E. Ackerman

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