Even with advanced automated driving technology, transit vehicles including public transit buses and vans are “highly likely” to require the presence of a qualified human operator, according to a report issued Thursday by Traffic21, a transportation research institute at Carnegie Mellon University.
Human operators will likely be required in part because transit buses operate in a complex, ever-changing urban environment alongside pedestrians, bicyclists and other road users, the report says. Transit operators also interact with passengers and are responsible for their safety on board the vehicle.
While advanced driver assistance systems such as lane-centering and pedestrian warnings can improve safety, higher levels of automation can create their own safety issues, the report said.
When an automated driving system faces a situation it can’t resolve, it turns control over to the operator, and that’s when “the human is taking over in a very stressful, complex situation,” said Nikolas Martelaro, CMU assistant professor and an author of the report.
The act of driving, which he described as both a cognitive and physical activity, is “where people are pretty good at operating.” But, “When you're just watching something, it can become quite tiring,” Martelaro explained. Simply put, if a driver isn’t fully alert to the situation around the vehicle they are operating, but suddenly needs to take over at a critical moment, they may not be ready.
There are other common situations that can boggle the mind of an autonomous vehicle. The study points to some occurrences that drivers encounter every day: other drivers and cyclists using hand signals to communicate; police using hand signals to direct traffic; and eye contact between drivers to resolve intent. “There is no parallel mechanism to communicate between autonomous vehicles and the rest of the world,” the study stated.
Meanwhile, some autonomous vans, buses and shuttles have already been put into limited service. Just this month, a 27-foot, 22-seat self-driving bus began operating along a 2.5-mile route between the Michigan State University campus and a commuter parking lot. A licensed bus driver and technician are onboard at all times.
EasyMile’s 12-passenger shuttles are also in use within a few business parks and residential communities. Though the EasyMile shuttles did experience a setback in 2020 when the National Highway Traffic Safety Administration suspended service following an incident in Columbus, Ohio, when a woman fell from her seat in one of the vehicles.
The TWU is praising new, independent research from @CarnegieMellon that urges the use of human operators onboard vehicles as public #transit agencies consider integration of automated technologies including #autonomousVehicles (AV) into their operations. @TwuSamuelsen pic.twitter.com/PetCLQtuJJ— TWU (@transportworker) May 19, 2022
Martelaro also referenced another transportation mode where automation has been commonplace: commercial airliners. “Aviation has been automated for a very long time and those systems have made planes safer,” he said. “However, they've also introduced a number of complex situations that pilots have to manage.”
When US Airways flight 1549 struck a flock of geese that shut down both engines just minutes after taking off from New York’s LaGuardia airport, veteran pilot Captain Chesley Sullenberger took control of the aircraft, landed it safely in the Hudson River, and saved the lives of 150 passengers and five crew members.
“There's a reason why we still require qualified pilots because that's the safest way to operate an aircraft,” said Greg Regan, president of the Transportation Trades Department, AFL-CIO.
“Technology can be really helpful in improving safety, but it needs to be along the lines of improving the operator’s ability to do their job in a safe manner.”
There are 162,850 transit operators currently employed in the United States, many of them represented by TTD member unions. Regan said unions have not been “anti-technology.” Rather, he explained, “We want to make sure that as technologies are integrated into our system, that it is done in the safest possible way.”
There are certain challenges that only an operator can handle effectively, he noted. He also said that he’s asked transit agencies to engage unions early in discussions around automation, adding that “we need strong federal rules” to govern this technology.
As local leaders continue to navigate the complexities of adopting AV technology, the CMU report makes five policy recommendations:
- Further research by the U.S. Department of Transportation on the stresses and demands placed on operators from automation;
- Research on systems that can improve a transit operator’s ability to maintain safety;
- New oversight measures to ensure that safety isn’t reduced by autonomous buses operated without a human on board;
- A hazard analysis of higher-level autonomous driving systems;
- And DOT investments in data collection, data sharing among agencies and oversight of automated transit operations.
Regan suggested taking the big picture into account. “These are complex questions that will have a lot of ramifications,” he said. "We cannot view these issues simply … it has to be about how this is going to benefit our society as a whole."
Funding for the CMU report came from the U.S. Department of Transportation and the Hillman Family Foundation.