In cities and countries around the world, drivers use a range of hand signals to communicate with other drivers. Lightspring/Shutterstock.com
Recently, while on my way to the University of Pittsburgh’s campus, I made a quick “Pittsburgh left” – taking a left turn just as the light turns green – while facing a driverless car.
Instead of jolting forward or honking – as some human drivers would be tempted to do – the car allowed me to go. In this case, the interaction was pleasant. (How polite of the car to let me cut it off!)
But as a sociolinguist who studies human-computer interaction, I started thinking about how self-driving cars will communicate with the human drivers they encounter on the road. Driving can involve a range of social signals and unspoken rules, some of which vary by country – even by region or city. How will driverless cars be able to navigate this complexity? Can they ever be programmed to do so?
Here in Pittsburgh, Uber has tested self-driving cars with a backup driver behind the wheel; in Phoenix, Waymo’s cars operate in a limited part of the city without any backup driver at all.
We know the driverless cars are equipped with a technology called LIDAR, which creates a 360-degree image of the car’s surroundings. Image sensors can interpret signs, lights and lane markings. A separate radar detects objects, while a computer incorporates all of this information along with mapping data to guide the car.
Although ideally autonomous vehicles will be able to “talk” to one another in order to allow smoother navigation and reduce crashes, this technology is still in the early stages.
But any autonomous vehicle will also need to be able to interact with traditional cars and their drivers, as well as pedestrians, bikes and unforeseen events like lane closures, disabled stop lights, emergency vehicles and accidents.
This is where things can get murky.
For example, if you’re driving and pass a speed trap, you might flash your headlights at drivers coming in the other direction to let them know. But flashing headlights can also mean “your high beams are too bright,” “you forgot to put your headlights on” or “go ahead” in situations where it’s unclear who has the right of way. In order to interpret the meaning, a person will consider the context: the time of day, the type of road, the weather. But how would an autonomous vehicle react?
There are other forms of communication to help us navigate, ranging from honks and sirens, to hand signals and even bumper stickers.
Of course, humans use all sorts of hand gestures – waving a car in front of them, indicating that another driver needs to slow, and even giving the finger when angry. Sounds can communicate love, anger, arrivals, departures, warnings and more. Drivers can express total disapproval with a hard, extended hit of the horn. Of course, emergency sirens encourage drivers to make way.
But specific meaning can vary by region or country. For example, a few years ago, Public Radio International ran a story about the language of honking in Cairo, Egypt, which is “spoken” primarily by men. These honks can have complex constructions; for example, four short honks followed by a long one mean “open your eyes” to warn someone who is not paying attention.
Traffic moves through Tahrir Square, in Cairo, Egypt. AP Photo/Hassan Ammar
In Pittsburgh, people tend to honk before going through a short, narrow or curvy tunnel. In Morocco, where I’m originally from, drivers perform varied honks when passing; they’ll honk once before passing to secure cooperation, again as they pass (to signal progress), and lastly after they pass to say, “thank you.” Yet this might be confusing – or even perceived as rude – to drivers in the U.S.