Making pedestrians safe in driverless cars
There are currently two safe ways to cross a street
The number of pedestrians killed on U.S. highways has increased by 25 percent from 2010 to over 5,000 people in 2015.
Since we were children, we have learned that it is important to maintain eye contact when approaching cars. This is not possible with autonomous vehicles. Even if someone is sitting in the driver’s position, they will still be a passenger with little or no control over the vehicle’s behavior. This passenger could be doing work, watching movies, or even dozing off while oblivious to the road ahead.
There will be other ways for cars and people to communicate. There is no widely accepted method to do this. My research and that of a few technology companies, automobile manufacturers, and startups are exploring different types of visual signaling – such as a driver waving someone across the street or flashing their car’s lights to indicate they yield the right of the way. Doing this is quite complex.
Nissan has developed a system that communicates with pedestrians.
The problem is that people react differently when they see an autonomous vehicle approaching. Scholars from Virginia Tech Transportation Institute and the University of California San Diego made headlines by driving vehicles on public roads using drivers who were carefully disguised to make the cars appear driverless. The Humans and Autonomy Lab at Duke University is investigating how driverless cars will communicate with pedestrians.
A standard U.S. “Don’t Walk” signal. S Rock/Shutterstock.com
Despite federal guidelines on stationary pedestrian traffic signals in today’s transportation world, there are no standards for vehicle-to-pedestrian communications at the moment. It is important to establish them: Common crossing signals are needed at intersections across the country. This makes both pedestrians, and drivers, safer. We don’t know which methods work best.
What would the sign say? It could be on the roof, the bumper, or anywhere in between. It would need to be able to communicate in different languages. Or should everyone agree on a nontext symbol like the ones in airports so that anyone can understand it? Would the car play music or speak? All age groups, levels of education and geographical locations must understand the signal.
What should the signs look like
It may be possible to use a text phrase such as ” safe crossing ” for a pedestrian crossing in front a car on a road with two lanes. There are more complex scenarios. Does “safe to pass” mean that a car won’t be approaching the next lane when crossing a 4-lane road? Which pedestrian is being directed by the “safe to cross message” when multiple pedestrians are crossing the street from opposite directions?
It is important that these signs look good. The letters must be six inches tall to make it possible to read a message such as “safe to cross.” This is the standard distance for the stationary crossing signals. This would mean putting the notes on a display nearly four feet wide. The messages on moving vehicles would need to be larger.
A sign is worthless if no one looks at it. A study we conducted last year raised this concern. We compared the different types of displays that were placed on the front of vans disguised so they looked like there was no driver. Only 12 percent of pedestrians relied on the displays to decide when to cross. The majority of people used their old strategies for crossing, such as assessing the speed and distance between oncoming cars to ensure they had enough time to cross.
Labs such as ours, and those in Virginia, California, and elsewhere, will continue to study how pedestrians react, so that we can ensure the safety of everyone. These efforts will likely lead to more people seeing a car being driven by a scientist in a car seat.