Highway Accident Brief 20/01 details the NTSB’s investigation of the collision of a 2018 Tesla Model 3 car with a 2019 International semi-tractor trailer on U.S. Highway 441 in Delray Beach, in which the 50-year-old driver of the car died. The 45-year-old truck driver was uninjured.
The crash happened as the truck was attempting to cross the southbound lanes of U.S. 441 and turn left into the northbound lanes. As the truck approached the stop sign at the intersection, it slowed but did not come to a full stop before beginning to cross the southbound lanes of the highway. The car driver, traveling southbound at a recorded speed of 69 mph, did not apply the brakes nor take any other evasive action to avoid the truck crossing in front of him. The Tesla hit the left side of the trailer just aft of its midpoint. The roof of the car was sheared off as the car struck the trailer, traveled under it, and continued south before coasting to a stop in the median about 1,680 feet from the point of impact.
System performance data from the Tesla showed the driver was operating with the “Autopilot” engaged at the time of the collision. Data from the vehicle indicated the Tesla was traveling in the right lane of U.S. 441 when the driver activated the Traffic-Aware Cruise Control at a cruise speed of 69 mph – 12.3 seconds before impact. The driver engaged “Autosteer” 2.4 seconds later, which activated the “Autopilot” partial automation driving system. The system did not detect steering wheel torque for the final 7.7 seconds before the collision. The car’s forward collision warning and automatic emergency braking systems did not activate before the crash and there was no evidence of system- or driver-applied braking or steering before impact. NTSB investigators noted in the report that the Delray Beach highway operating environment, like the cross-traffic conditions found in a 2016 Williston, Florida, crash, was clearly outside the “Autopilot” system’s operational design domain in that the highway did not have limited access (it had 34 intersection roadways and private driveways in the 5-mile region encompassing the crash location).
Tesla informed the NTSB that the installed forward collision warning and automatic emergency braking systems on the Model 3 Tesla in the Delray Beach crash were not designed to activate for crossing traffic or to prevent crashes at high speeds and therefore, according to Tesla, the “Autopilot” vision system did not consistently detect and track the truck as an object or threat as it crossed the path of the car.
The NTSB determined the probable cause of the fatal crash to be the truck driver’s failure to yield the right of way to the car, combined with the car driver’s inattention due to overreliance on automation, which resulted in the car driver’s failure to react to the presence of the truck. Contributing to the crash was the operational design of Tesla’s partial automation system, which permitted disengagement by the driver, and the company’s failure to limit the use of the system to the conditions for which it was designed. The failure of the National Highway Traffic Safety Administration to develop a method of verifying manufacturers’ incorporation of acceptable system safeguards for vehicles with Level 2 automation further contributed to the crash.
“The Delray Beach investigation marks the third, fatal, vehicle crash we have investigated where a driver’s overreliance on Tesla’s “Autopilot” and the operational design of Tesla’s “Autopilot” have led to tragic consequences,” said NTSB Chairman Robert Sumwalt. “In the Mountain View crash, that overreliance was coupled with the equally deadly menace of distraction, demonstrating the insidious nature of the threat and the lack of policy and technology to eliminate it,” said Sumwalt.
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