It’s a bit strange that all the world has cracked down on drunken driving while ignoring drowsy driving. Maybe it’s because drunkenness is a vice or because it’s so easy to measure the concentration of alcohol in the blood.
But if you just want to improve your own driving safety, you don’t need a law—just a car that can tell when you’re getting tired. Some of today’s cars can do that, but they mostly look for severe fatigue—the kind that can be handled only by pulling over to the side of the road right away. Maybe that’s putting things off until it’s too late.
Now researchers at the University of Washington, in Spokane, have developed a way to detect incipient sleepiness. Their system uses movements of the steering wheel, the one variable out of the dozens they studied that best captures the key information. And unlike systems that train cameras on the road to detect departures from the lane, this method works day and night, in any kind of weather.
“You can detect fatigue even without gross discursion into the next lane,” says the project leader, Hans P.A. Van Dongen, who heads the university’s Human Sleep and Cognition Laboratory.
He says this system would be cheap and easily integrated into existing lane-departure warning systems, covering their bad-weather blind spots. It might also complement systems that monitor the driver’s eyes, or randomly prompt him do something and then measure how long it takes him to do it. And when several of these systems work together, the car can detect a driver's fatigue with more subtlety.
Subtlety matters, because fatigue isn’t a cut-and-dried thing (as drunkenness clearly is). “A fatigued brain is impaired, but not all the time,” Van Dongen says. “Most of the time, it’s actually working fine, but in an unpredictable manner. That makes it different and perhaps even more dangerous.”
Van Dongen and Pia Forsman, a post-doctoral student, have patented their method, which involves putting a sensor in the steering wheel and feeding the output to a processor that filters the data for telltale signs of fatigue. Because it can be installed in existing systems, it doesn’t need an interface of its own to tell the driver, "You are getting sleepy… S-L-E-E-P-Y."
In countries where drunken driving is fully under control, drowsy driving looks to be the biggest remaining causes of driver error. In Sweden, for instance, it accounts for 20 percent of all road accidents. That makes it ripe for the kind of law enforcement that can work only if the car itself becomes the policeman.