Autonomy 101: Teachable Accidents

On the first day of a year-long pilot program in Las Vegas, a Navya driverless shuttle bus was hit by a delivery truck. The accident was a minor fender bender caused by human error, providing immediate feedback about how self-driving vehicles perform in real world conditions—and underscoring the need for improvement.

The driver of the truck was ticketed, no one was hurt and the bus was back in service the next day. By most accounts the bus did what it was programmed to do, and the accident probably never would have happened if the truck was equipped with the same advanced sensors and control algorithms.

But that’s not how it works. As semi- and fully autonomous cars are tested and introduced they will have to learn how to share the road and communicate with driver-operated vehicles, pedestrians and bicyclists. To be effective, they will have to expect the unexpected, adapt their behavior and, in some cases, act more like humans.

In the Las Vegas program, the Navya bus shuttles passengers along a 0.6-mile loop in the city’s new downtown Innovation District. There are three pre-set stops along the route, all users are required to wear seatbelts and an attendant rides along to observe the operation, answer questions and help put passengers at ease.

The 12-person shuttle is equipped with an array of sensors, GPS and other safety features. To further improve safety and traffic flow, the bus is linked with surrounding traffic lights—a first for autonomous vehicles on public roads in the U.S. Powered by a 33-kWh battery, the electric bus has a top speed of 25 mph and takes about eight hours to be fully charged.  

The shuttle’s inauguration ceremony earlier this month was highlighted by an appearance by race car driver Danica Patrick. Passengers were eager to try the free service, which is sponsored by AAA, and the day proceeded smoothly—at least for the first hour of operation. That’s when the bus encountered the delivery truck, which was stopped in front of it. Sensing the truck’s movements, the bus also came to a stop a safe distance away.

The driver of the articulated truck then started backing up to swing the truck’s trailer into a side alley. With his focus on maneuvering the trailer, the driver didn’t notice the bus on the other side and grazed the front fender with the tire of the truck cab.

Watching the truck slowly back into them, the shuttle’s occupants note that the accident could easily have been avoided. In addition to the truck driver being more attentive to his surroundings, the shuttle bus also could have benefited from having a human driver. Passengers say there was plenty of room behind the shuttle for it to back up once it became clear what the truck was doing. Another option: honking the horn to alert the truck driver to the bus’ position.

But the bus isn’t programmed to automatically reverse as a potential evasive maneuver. An automated horn—or one for the attendant to use—also would have come in handy. These are little things that can be easily corrected as autonomous vehicles are tested on public roads and exposed to the multitude of scenarios humans routinely encounter every day.  

While the overwhelming bulk (more than 90%) of all accidents are blamed on human error, people also have the ability to improvise and avoid accidents. As with the best drivers, self-driving cars need to learn from their mistakes—and share the results with others. To this end, a team from the National Transportation Safety Board went to Las Vegas to assess the accident. Navya and its partners also regularly download  and analyze video footage and sensor information from the shuttle bus to look for ways to improve its operation. In addition, AAA is surveying riders and other people who encounter the bus about their experiences. Navya, traditional automakers, suppliers and tech companies also are conducting similar tests—and accumulating data—in cities around the world.

As the Las Vegas incident demonstrated, self-driving vehicles aren’t perfect. This isn’t the first such accident, and it won’t be the last. But it’s important that what happened in Vegas, doesn’t stay there. Class is in session.