In a typical minor traffic accident, drivers exchange insurance information and get on with their day.

But tap the bumper of an autonomous vehicle and the feds are on the case.

That's what happened following a minor collision in Las Vegas in 2017 between a truck-tractor combination vehicle and an autonomous shuttle carrying seven passengers and an attendant.

In an accident investigation report released in July, the National Transportation Safety Board (NTSB) said the truck driver’s actions and the autonomous vehicle attendant’s lack of easy access to a manual controller were the probable cause for the collision.

The accident caused minor damage to the lower left front of the shuttle’s body and a minor abrasion to the truck’s tire.

“The NTSB would normally not investigate a minor collision, but the involvement of a highly automated vehicle warranted having our investigators examine the circumstances surrounding the collision,” said Kris Poland, deputy director of the NTSB’s Office of Highway Safety. The NTSB said it wanted to examine the process of introducing an autonomous shuttle onto public roads as well as the role of the operator, the vehicle manufacturer and the city. The safety board also examined the technology and safety considerations that were in place at that time.

Accident scene. Source: NTSBAccident scene. Source: NTSBShuttle specs

The autonomous shuttle was a two-axle, battery-powered test vehicle designed primarily for autonomous operation. It did not have a steering wheel, brake pedal or accelerator pedal. Instead, the shuttle allowed for manual operation using a hand-held controller. It could operate autonomously only on a predetermined route that had been fully mapped.

The NTSB said the route was planned by Keolis (a public transportation service operator), Navya (the shuttle manufacturer) and motor club AAA (sponsor of the shuttle) with input from the city. Navya and Keolis had the required state and federal approval to test autonomous shuttle operations on public roads, the NTSB said.

The collision happened after the shuttle turned from Carson Avenue onto South 6th Street, where the truck was backing into an alley. The truck driver said he saw the shuttle turn onto 6th Street and assumed it would stop a “reasonable” distance from the truck.

Waving arms and a crunch

According to Navya’s incident report, the shuttle’s sensor system detected the truck at 147.6 ft and tracked it continuously as the truck backed up. Programmed to stop 9.8 ft from any obstacle, the shuttle began to decelerate when it was 98.4 ft from the truck. When the shuttle was 10.2 ft from the truck and nearly stopped, the attendant pressed one of the emergency stop buttons. The NTSB said the attendant and passengers waved to gain the truck driver’s attention. However, 11 seconds after the shuttle stopped, the right front tire of the slow-moving truck struck the shuttle.

The NTSB said that the shuttle was equipped with numerous sensing devices that provided a 360-degree view of the environment with hazard detection capabilities. Sensing devices included eight light detection and ranging (lidar) sensors, two stereoscopic cameras and a differential global positioning system. The shuttle was also equipped with a dedicated short-range communication system and a long-term evolution antenna that communicated with traffic signals along the route.

Sensing equipment as identified by federal accident investigators. Source: NTSBSensing equipment as identified by federal accident investigators. Source: NTSBNavya could monitor the shuttle’s performance in real time from its control center in Lyon, France. The shuttle was equipped with a Lytx DriveCam monitoring and recording device that tracked driving metrics and recorded telematic and visual information triggered by critical events.

Prior to the collision, the hand-held controller for manual operation was stored in an enclosed space at one end of the passenger compartment. The NTSB said the attendant did not retrieve the controller during the event. Since the accident, Keolis implemented a new policy to make the controller more accessible, allowing attendants to remove it from storage at the start of a trip and keep the controller available throughout a trip.

Test programs

The NTSB said that the year-long pilot program in Las Vegas was the first in the country to operate an autonomous shuttle in live traffic and open to the public. According to AAA, the shuttle operated for 1,515 hours and carried 32,827 riders in total during the program.

Las Vegas is planning another pilot program involving autonomous shuttles, the GoMed project, which would operate four autonomous shuttles on a fixed route from the downtown transit center to the Las Vegas Medical District.

Autonomous shuttles are also operating on an experimental basis in several other U.S. cities. For example, in April 2018, a Navya shuttle carried passengers on test rides around the campus of the University of Wisconsin at Madison. In 2016, Local Motors demonstrated its autonomous shuttle Olli, made up of 3D-printed parts, on private roads around National Harbor, Maryland. In January 2019, the company received permission from the state for Olli to begin carrying passengers on public roads in the same area.

And officials in Washington, D.C., are seeking a company to run a pilot program using an autonomous shuttle to connect the Smithsonian museums to the nearby Potomac waterfront.