No one knows yet exactly why a Tesla Model X crashed last Friday on U.S. 101 in Mountain View, killing its 38-year-old driver.
But both the carmaker and federal and state investigators are looking at a range of factors surrounding the crash and its aftermath, including whether the electric vehicle's Autopilot system was engaged, the apparent absence of a safety barrier that may have made the crash impact more severe and the fact local firefighters needed to call Tesla for help in controlling the battery fire that followed the crash.
The crash occurred just before 9:30 a.m. Friday, when the Model X struck a concrete highway divider along southbound U.S. 101. The CHP reported the crash occurred "at freeway speeds," and witnesses said the Model X burst into flames immediately.
Authorities identified the driver as Wei Huang, 38, of Mountain View, though he was known to family, friends and associates as Walter Huang. He died at Stanford University Medical Center several hours after the crash.
Huang was a longtime software engineer at Electronic Arts before taking an engineering job at Apple last November. Huang was lived in Foster City and was married with two children.
The CHP confirmed Thursday that Huang's family has told investigators he had reported problems with his Model X's Autopilot system at the same spot where he crashed Friday.
Report: Vehicle 'Would Swivel Toward Barrier'
ABC7 on Wednesday night quoted Huang's brother as saying Walter Huang had told family members of multiple occasions when the Model X "would swivel toward that same exact barrier during auto-pilot."
Will Huang told ABC7 that his brother brought the car into a dealership to have the problem checked out, but technicians could not duplicate the issue.
In response to the report, Tesla said it had no records of a service visit specifically related to the car's Autopilot system.
The company said in a statement late Tuesday that because of severe damage to the SUV, it has been unable so far to recover data from the car's onboard computer. The data could show whether the car's semi-autonomous Autopilot system was engaged at the time of the crash, whether the vehicle's brakes were applied before the collision and other information.
Tesla's statement highlighted the role of a missing safety barrier -- called a crash attenuator -- at the crash site.
The crash occurred at a point where the left lane of southbound 101 exits onto a flyover ramp that carries traffic to southbound Highway 85. As traffic moves toward the ramp, it's separated from the flow of southbound 101 by a concrete divider.
Google Streetview images show that since 2011, Caltrans has replaced a simple guardrail at the site and installed a crash attenuator -- in this case, a steel framework designed to collapse upon impact to dissipate the energy of a crash -- to reduce the danger to motorists who may hit the concrete wall.
Tesla's statement compares a Streetview image from November to a picture captured by a passing vehicle's dashboard camera last Thursday and says the images prove the crash attenuator was not in place. The company makes a further claim, too: that the absence of the safety barrier was primarily responsible for the devastating damage the crash caused to the company's vehicle.
"The reason this crash was so severe is that the crash attenuator, a highway safety barrier which is designed to reduce the impact into a concrete lane divider, had either been removed or crushed in a prior accident without being replaced," Tesla said. "... We have never seen this level of damage to a Model X in any other crash."
The National Transportation Safety Board told the Washington Post the agency is "looking at the damaged attenuator and looking at an undamaged one and looking at if it had an effect."
The California Highway Patrol reported Thursday that the crash attenuator had been damaged in a crash March 12.
Caltrans said in a statement late Wednesday afternoon that the agency is "reviewing the facts and circumstances of this incident and are cooperating with the National Transportation Safety Board's ongoing investigation. Safety is our top priority and Caltrans will carefully evaluate the investigation's findings and take appropriate action."
Previous Damage Visible in Online Images
A review of Google Streetview images over the last seven years shows the crash barrier was installed between May 2011 and December 2013. Images from 2014 through 2016 depict it intact, but it's absent in pictures captured in January and February 2017, apparently after a crash at the site. The attenuator was back in place by late last fall.
Tesla's statement came after the National Transportation Safety Board announced it has dispatched two investigators to look into the post-crash fire and the steps that firefighters and Tesla technicians had to take to make the Model X safe to remove from the crash scene.
Fires are a well-known hazard for conventional gasoline-fueled vehicles. But both manufacturers and emergency responders are facing unique fire hazards posed by battery-powered vehicles like the Model X involved in Friday's crash. California has about 350,000 electric vehicles on the road -- and hundreds of thousands of hybrids and plug-in hybrids that use similar battery technology.
The high-voltage batteries used by Tesla and other electric carmakers -- actually a collection of modules containing hundreds of small lithium ion cells -- are known to pose a fire risk if the battery compartment is breached.
Tesla and other manufacturers publish emergency guides for first responders with special instructions on how to deal with the risk.
"If the high voltage battery catches fire, is exposed to high heat, or is bent, twisted, cracked, or breached in any way, use large amounts of water to cool the battery," Tesla's 2016 emergency response guide for the Model X warns. "DO NOT extinguish with a small amount of water. Always establish or request an additional water supply."
The guide adds that the batteries can burn for 24 hours and that responders should use thermal imaging equipment to ensure that a fire is actually out.
Firefighters Turned to Tesla for Help
Mountain View Fire Chief Juan Diaz told reporters Friday that his firefighters had only a limited amount of water to try to douse the battery fire that broke out after the Model X crash. That led the Fire Department to seek outside expertise -- from Tesla itself.
Diaz said the department was put in a difficult situation. Fire crews had 500 gallons of water at the scene, but getting any more would have required running 2,000 feet of thick fire hose across Highway 101, which would have been catastrophic for traffic in both directions, Diaz said. But letting the car continue to burn on a busy highway, destroying the battery, would have been a bad choice as well, he said.
"In the middle of the Highway 101 freeway, that's not something we want to do," he said. "And it's not good for the environment with the byproducts of combustion."
Fire crews used the available supply of water and contacted the manufacturer of the vehicle, Palo Alto-based Tesla, to assist in getting the battery's temperature under control. Diaz said the engineers essentially disassembled a portion of the car battery on the spot, and that subsequent thermal imaging showed that the battery was no longer unstable.
It took about 5½ hours after the crash before the vehicle was considered stable enough to move. Diaz said crews monitored the wreckage at an impound yard because of the possibility of reignition.
Tesla's share price has fallen nearly $50 -- from $304 at the open of trading Tuesday to $257 late Wednesday -- partly in response to news of the NTSB probe into the Friday crash. Analysts say investors are also selling Tesla shares because of a credit downgrade announced Tuesday night.
<a id="update" Updates:
5 p.m. Wednesday, to include response from Caltrans.
1 p.m. Thursday, to include new details about victim Walter Huang and claims that he had complained about his Tesla Model X's Autopilot system.