In the March 2018 crash, the driver of a Tesla Model X was traveling on southbound Highway 101 with the vehicle's "Autopilot" function on. The vehicle reportedly veered left and entered the paved divider between Highway 101 and the Highway 85 exit ramp, where it struck the median at about 71 miles per hour. The crash breached its high-voltage battery, causing the vehicle to catch fire.
A bystander pulled out the driver shortly before the Tesla was engulfed in flames. The driver, later identified as 38-year-old San Mateo resident Wei Huang, was taken to a hospital and later died of his injuries.
The NTSB investigation found that the carpool flyover divider was supposed to have what's called a crash attenuator, a long device with a hydraulic cylinder and cable assembly designed to "telescope" and absorb impact when a vehicle hits it at high speeds. Attenuators are meant to slow down a vehicle and reduce injuries.
On the day of the crash, however, the attenuator was damaged to the point of being "nonoperational," the report found. It had been smashed in by a Prius in a solo-vehicle crash 11 days prior and had yet to be replaced. In that incident, the Prius struck the attenuator at 75 miles per hour, and the driver survived with injuries that included a fractured finger and a tear in the "intimal layer" of the aorta.
NTSB investigators found that the crash location on Highway 101 has a history of problems, with the attenuator needing to be repaired and replaced more frequently than any other left-exit crash attenuator in the region and more than twice as often as any other location. In the three years leading up to the March 2018 crash, drivers struck the attenuator at least five times, including one fatal accident. It was hit again on May 20, 2018, two months after the fatal Tesla crash.
Although Caltrans' official policy requires the replacement of crash attenuators and other safety hardware within one week, the agency has a history of missing the mark, the NTSB report found. In a fatal crash at the same location in November 2015, Caltrans had not replaced a damaged attenuator in 45 days. In another location, an attenuator damaged in January 2017 was not repaired until April that year.
"Safety remains Caltrans' top priority, we are in the process of reviewing today's report in conjunction with the California State Transportation Agency to determine the next steps," said Matt Rocco, Caltrans' spokesman, via email.
In the weeks leading up to the Tesla crash, NTSB investigators found that the CHP had responded to the solo-vehicle crash involving the Prius on March 12 but did not notify Caltrans that the attenuator had been damaged — a violation of policy and interagency operational agreements. Caltrans maintenance staffers discovered the attenuator was damaged on March 20, three days before the fatal collision, took pictures and forwarded it to their supervisor, according to the report.
No date was scheduled to fix the attenuator in the lead up to the crash, due in part to staffing shortages and the challenges of finding a replacement attenuator. The safety hardware was finally replaced on March 26 — 14 days after the initial damage and three days after the fatality.
The 9-page report recommends that a "correction action plan" be put in place that guarantees the timely repair of traffic safety devices, including attenuators, and better tracking of compliance with required timelines of the roadway repairs.
The report released Monday is part of an ongoing investigation and is not the final report. It was released to give formal recommendations to Caltrans in order to hasten policy changes that could improve traffic safety.
"Rather than wait to complete all facets of this crash investigation, we have moved ahead with issuing this safety recommendation report in the interest of motorists' safety," Robert Molloy, director of NTSB's Office of Highway Safety, said in a statement Monday.
NTSB released an earlier preliminary report stating that the Tesla's Autopilot function was on in the moments leading up to the crash, and that the vehicle increased to 70.8 miles per hour before striking the damaged attenuator. Huang's widow filed a wrongful death lawsuit against Tesla in May, arguing that the company's Autopilot function and emergency braking system were defective. The suit also accuses Caltrans of failing to maintain safe conditions at the location of the crash, arguing the attenuator was not replaced in a timely manner and that the state agency's actions were "negligent and careless."
Tesla was assisting in the NTSB investigation for one month, but was booted in April 2018. The agency accused Tesla of releasing incomplete information on the crash that speculated on the cause of the accident, strongly suggesting that Huang was at fault.
The Monday report does not reveal additional details on the Autopilot function and its potential involvement in the crash.
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