Inadequate highway markings caused a fatal Greyhound bus crash in California last year that killed two people and injured 13 others, including the driver, federal officials said Tuesday.
The National Transportation Safety Board report said that the lack of reflective warning markers on U.S. Highway 101 made the bus driver think he was in the connector lane when he was actually heading straight into a concrete barrier on that dark, rainy morning.
The California Department of Transportation, or Caltrans, did not properly mark the area separating the two lanes, the board said.
Caltrans didn't immediately return a call seeking comment.
"This crash did not have to happen because the barrier that the bus hit should have been visible, even in the bad weather, but it was not," said NTSB Acting Chairman Bella Dinh-Zarr.
The bus was on an overnight trip from Los Angeles to San Jose when it plowed into safety barrels and flipped on its side on the rain-soaked highway early on Jan. 19, 2016.
Passengers described hearing a bang and a loud scraping sound for about 10 seconds as the bus see-sawed along the asphalt.
The driver, who was one of those sent to the hospital, stopped for a caffeine jolt at the last stop before the wreck, about 30 miles south in Gilroy, the California Highway Patrol said at the time of the accident. But federal officials didn't mention fatigue as a factor.
Dinh-Zarr said that even though the bus had seat belts only two of the 21 passengers were wearing them and that contributed to the severity of the injuries.
"The crash would probably have resulted in fewer deaths and injuries if the occupants had worn their seat belts," she said.
The NTSB recommended that Caltrans add road markers and improve exit signage. It also said Greyhound should brief its passengers on the importance of wearing seat belts.