Last Friday, Tesla drivers first reported receiving a software update that included “Traffic Light and Stop Sign Control,” which is designed to slowdown and stop the vehicle for visible traffic lights or stop signs.
A visual prompt appears on the dashboard as the car approaches an intersection that reads, “Stopping for traffic control in 300 ft. Use accelerator or cruise stalk to continue.” The number of feet in the message appears to change depending on how close the vehicle is to the stop sign or traffic signal.
“This feature will be conservative, slowdown often at first, and will not attempt to turn through intersections,” Tesla says in a statement shown in the console screen of Tesla owners’ vehicles after the update is installed.
Slowing when it shouldn’t isn’t the only problem. Tesla warns Autopilot may not stop the car when it should.
“This feature may not stop for all traffic controls,” Tesla cautions in the statement. Drivers are reminded that they must continue to pay attention and be ready to take immediate action.
Missy Cummings, a Duke University professor who studies autonomous systems, cautioned that the feature may lead to traffic crashes, especially as other drivers may not expect a Tesla in front of them to slow at a green light.
“There’s no upside to this software,” Cummings said. “There’s a capability being released to the general public that’s known to have significant defects.”
“They’ve released software that they know can be wrong, they tell you it’s wrong, and yet you still accept it and you pay extra for [full self-driving],” Cummings said. “I’d want my money back.”
Tesla did not immediately respond to a request for comment.
Paul Godsmark, chief technology officer of CAVCOE, the Canadian Automated Vehicles Centre of Excellence, said he’s concerned the new Tesla feature will lull drivers into a sense of complacency, and lead to crashes, as the system’s flaws must surface when drivers least expect it.
“I think it’s a recipe for disaster, ” Godsmark said. “If it’s going to stop at 9,999 lights and kill you at number 10,000, how are you going to keep your concentration?”