WASHINGTON (Reuters) - California state transportation officials failed to repair a highway safety device seriously damaged in a high-speed crash 11 days before a fatal collision in March 2018 involving a Tesla in Autopilot mode, the National Transportation Safety Board (NTSB) said Monday.

FILE PHOTO - The logo of Tesla is seen on Model X electric car at showroom in Taipei, Taiwan August 11, 2017. REUTERS/Tyrone Siu

In the first crash, the NTSB said the driver of a 2010 Toyota Prius was traveling in excess of 75 miles per hour (121 km per hour) when the car struck a crash attenuator, which is designed to absorb crash forces before a vehicle hits a concrete median barrier. The driver survived with no major injuries.

In the second crash 11 days later, the driver of a 2017 Tesla Model X was going 71 mph (114 kph) when he struck the same attenuator on US-101 in Mountain View, California. The front of the Tesla separated from the rear and then collided with two other vehicles. The crash killed the driver of the Tesla, 38-year-old Apple engineer Walter Huang.

“The safety benefits of a functioning crash attenuator were demonstrated by the differences between the level of driver injuries in the two March 2018 crashes that took place at this location,” the NTSB said.

The agency is still investigating the crash. Tesla and California did not immediately comment. The NTSB is investigating a number of crashes of Tesla vehicles in which the driver assistance system was in use. The system allows people to keep their hands off the wheel for extended periods.

The report said that after the March 11 crash the California Highway Patrol did not notify the California Department of Transportation of the damage to the attenuator as required.

The NTSB found “systemic problems within the California Department of Transportation (Caltrans) that negatively affect the timely repair of traffic safety hardware.”

State workers discovered the damaged attenuator on March 20 but no date for replacement of the attenuator was scheduled. It was finally replaced three days after the fatal Tesla crash.

The NTSB said in the three years before the Tesla crash, the attenuator was struck at least five times, including one crash that resulted in fatal injuries and was struck again in May 2018.

The NTSB previously found problems with Caltrans maintenance after reviewing a 2016 fatal crash involving a motorcoach that collided with an attenuator on US-101 in San Jose. In that case, the NTSB determined the attenuator had been damaged 44 days before the crash.