Will self-driving cars understand the finer points of traffic etiquette?
There are many unwritten rules of the road drivers and pedestrians have been expected to follow for decades. How will autonomous vehicles change the equation?
You're about to cross the street, but a car is coming.
Will the driver stop?
You make eye contact, the driver nods and you walk across.
These kind of interactions – "You go." "No, you go." – happen all the time. But what if there's no driver?
"As soon as you lose a driver in the front seat, you're going to lose that eye-to-eye contact and gesturing that occurs in right-of-way conflicts where somebody doesn't know who's going," said Andy Schaudt, project director with the Center for Automated Vehicle Systems at Virginia Tech. "Is this a problem? And could we find some sort of communication that makes it easier to navigate these situations?"
So, what's the equivalent of eye contact and a nod for an autonomous car? Nissan and Toyota have concept cars that display text to indicate whether a car is in autonomous mode and what it might be doing next.
"We considered text, but then you could have language issues," Schaudt said in an interview at CES in Las Vegas last month. "We considered symbols, but with symbols the recognition rate is really low. People think they're great, but they're not."
Instead, Schaudt's group, working with Ford, decided to test a light bar at the top of the windshield.
After testing on simulators, the researchers needed to see how pedestrians would react to a driverless car – and to the signal bar – on city streets.
A solid white light shows the vehicle is in full autonomous mode, a blinking white light shows acceleration and a pair of white lights moving side to side signals slowing and stopping.
But since driverless cars aren't capable of driving in cities entirely on their own yet, they took a normal Ford Transit and disguised the driver with a hood that looked like the back of the seat.
"We had to take a Wizard of Oz approach," Schaudt said. "We didn't tint the windows – we wanted people to look in and confirm that nobody was there."
They drove the fake driverless car around Arlington, Va., last summer and watched how people reacted.
"We were worried people might jump in front of it," Schaudt said. "But that didn't happen."
In total, the car drove 2,900 kilometres – half the time with the signals on. Mostly, people didn't react at all.
"We're still analyzing the data – but only 19 per cent of pedestrians ever looked up at the vehicle, whether the signals were on or not," Schaudt said. "I thought it would be higher than that, but it's really not. People are looking at their phones or they're having conversations."
Signals not essential?
Since driverless cars will follow the rules of the road, they won't be confused as to who has the right of way at an intersection. And if pedestrians go anyway, the cars will stop. That means the winks and nods might not be essential to safety.
"There's nothing in the driver's manual that tells you that you have to do anything with your eyes and hands to instruct pedestrians," said Paul Godsmark, chief technology officer with the Canadian Automated Vehicles Centre of Excellence. "Whenever pedestrians and motorists come together at the moment, we don't have this great system where a nod always means the same thing. If it was a big problem, it would be in the current vehicle regulations."
In fact, in the United States in 2016, pedestrian fatalities went up 11 per cent to nearly 6,000, the biggest single-year increase yet – and that's without fully autonomous cars.
Godsmark says some set of signals to show what a driverless car is doing, beyond just the signal and brake lights we have now, might be useful, but it's not a make-or-break problem.
"I think there's value in the car telling pedestrians what it's going to do, as long as we come up with a national standard," Godsmark said.
Instead of just letting pedestrians know what the car is going to do, developers are trying to allow the cars to predict what pedestrians are going to do. For instance, the car would decide that a pedestrian walking toward the road – or standing on the edge of the sidewalk looking across – might be about to cross.
"It's an intelligent system that can check on the intention of the pedestrian," said Fakhri Karray, director of the Centre for Pattern Analysis and Machine Intelligence at the University of Waterloo. "We want to provide as many lines of defence as possible."
Still, Karray thinks it will be important to let people know that a car is autonomous so they can be extra-cautious, especially in the first days of fully autonomous vehicles.
"People could have an app on their smartphone to warn them that the car coming is a driverless car," Karray said.
If there are visual signals, they'll need to be universal, he said. "How people will decipher these signals will be extremely difficult," Karray said, "They'll have to learn what these lights mean."
Virginia Tech's Schaudt said more research is needed to determine whether visual signals will actually make the cars safer on the road. But, whatever signals are decided on, he thinks people will be able to figure them out.
"In virtual-reality studies with the signals, it takes people two to three times to see them with the car in motion before they get it," Schaudt said. "How did you learn that green means go and red means stop? You learned it at one point in your life and now it seems intuitive."
The writer was a guest of Ford Motor Co. of Canada at CES. Content was not subject to approval.