NTSB criticizes Caltrans for slow repairs following fatal Tesla crash in Mountain View

Ongoing investigation also says CHP failed to inform Caltrans that earlier accident damaged crash attenuator on state Highway 85 carpool flyover lane

A new report found that Caltrans failed to promptly fix damaged traffic safety equipment on U.S. Highway 101, including a barrier involved in a fatal Tesla crash in Mountain View last year.

The report by the National Transportation Safety Board (NTSB) released Monday, part of an ongoing investigation into the crash on March 23, 2018, found that Caltrans had "systemic problems" that prevented the swift repair of safety hardware on state roadways — particularly where the state Highway 85 carpool flyover splits from Highway 101 in Mountain View.

Safety repairs that are supposed to be done within a week can take as long as three months to complete, according to the report.

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 Toyota 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, more than twice as often as any other location. In the three years leading up to the March 2018 collision, 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 collision 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 in March last year, 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 nine-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 in order 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.

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 collision, strongly suggesting that Huang was at fault.

Monday's report does not include additional details on the Autopilot function and its potential involvement in the crash. A full report on the battery fire and whether Tesla's driver assistance system had a role in the collision is tentatively scheduled for release in the first or second quarter of 2020.


Follow the Palo Alto Weekly/Palo Alto Online on Twitter @PaloAltoWeekly and Facebook for breaking news, local events, photos, videos and more.

Kevin Forestieri writes for the Mountain View Voice, the sister publication of

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7 people like this
Posted by Chris C.
a resident of Community Center
on Sep 9, 2019 at 6:35 pm

I wonder if the NTSB considered the angle of the sun and the paint used on the road. Really. I recall from my commute that when the sun is at just the right angle along that stretch the road markings disappear in the glare.

Like this comment
Posted by That MV Guy
a resident of Mountain View
on Sep 9, 2019 at 7:53 pm

Chris C., that does sound like a possibility. The sun would have been in front of the car that time of morning with the roadway headed roughly southeast. That might confuse camera-like optical sensors.

But I would think the laser scanner would have detected the unprotected barrier wall and avoided. Perhaps it's range/power is not adequate for that at high speeds.

If any Tesla employees who live around here have some info to offer without getting in trouble from the company, we're listening.

6 people like this
Posted by Nearby resident
a resident of Duveneck/St. Francis
on Sep 10, 2019 at 12:26 am

5 accidents in the same spot in relatively short time is not incidental, seems like a hwy design fault. Please put some serious thought into it.

8 people like this
Posted by Kristen
a resident of Mountain View
on Sep 10, 2019 at 5:46 am

This is a bad highway design. I live here. The left lane is an exit to another highway. Some people either don't pay attention or push the envelope and merge at the last second. They should put up 500 feet of white plastic dividers splitting the two lanes ahead of time. They installed these same 4' tall dividers on the Old Middlefield exit that is effective preventing people from changing lanes last minute.

10 people like this
Posted by Nayeli
a resident of Midtown
on Sep 10, 2019 at 12:32 pm

I agree, Kristen. Each time that we drive south on 101, there are vehicles that switch lanes at the last second. Most assume that the far-left HOV lane will continue going straight under the assumption that the the left-exit is optional.

The only other place that is confusing like this is the entrance to 101 going east from the Oregon Expressway. Every day, there are people who switch at the last possible moment. This has the added caveat of causing traffic issues.

In terms of this exit on 101: It would be nice if Caltrans could mark this particular stretch with very visible "must exit" signage and/or lane markers far enough away from the actual exit to give drivers (particularly those not familiar with this exit) time to be in the proper lane.

2 people like this
Posted by SouthPA3
a resident of St. Claire Gardens
on Sep 10, 2019 at 3:50 pm

This was a tragic accident. I was driving this stretch of 101 every weekday in this time period and recall noticing that the paint markings on this split in the road at the barrier being completely worn out or missing at the time of the accident and then suddenly repainted after the accident and barrier repair. Driving a Tesla now has shown me how much the autopilot feature utilizes this sort of marking for lane keeping. I suspect a simple paint strip would have helped to potentially save a life in this particular case if the vehicle was indeed under autopilot control.
What a shame. Condolences to Wei Huang's family.

3 people like this
Posted by Resident
a resident of Another Palo Alto neighborhood
on Sep 10, 2019 at 3:58 pm

Driving 101 SB from Marsh, it is very evident that the road surface is potmarked with the striping from the previous construction. These scratches are almost more pronounced than the actual lane marking stripes. As these stripes start to fade, I reckon the scratched old potmarks will be more visible in some conditions than the fading lane markings.

It is not acceptable for the road surface to be this bad and Caltrans should not allow such a busy highway have such poor safety markings.

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