HIGHLAND, Ill. – The National Transportation Safety Board said Tuesday a tired bus driver was the primary cause of the deadly Greyhound bus crash in July 2023 along Interstate 70 in Highland, Illinois.

The NTSB report said it found the bus driver was awake for more than 17 hours before the crash, the majority of which was spent on duty. Authorities revealed the driver worked highly irregular shifts that likely disrupted his sleep. They said he also has obstructive sleep apnea and diabetes that increased his risk of fatigue.

“I want to take a moment on behalf of the entire National Transportation Safety Board and offer our deepest condolences to those who lost loved ones or were injured in this tragic crash,” Jennifer Homendy, chair of the National Transportation Safety Board, said.

Three passengers were killed, and a dozen others were injured, including the driver, when the bus collided with three tractor trailers parked along the shoulder of an exit ramp near the Silver Lake rest area on westbound I-70 on July 12, 2023.

“In summary, staff found that the passenger’s statements, the failure of the driver to negotiate the roadway geometry and the crash dynamics point to driver fatigue as the primary cause of this crash,” Rafael Marshall of the NTSB said.

The NTSB said internal records from Greyhound show the driver was in four other crashes prior to the July 2023 crash in Highland. One of those crash reports listed the driver as being “fatigued” and “driving at an unsafe speed for traffic conditions.” In May 2023, the NTSB found the driver was included in a Greyhound report that tracks and ranks drivers who display the riskiest behaviors each month.

“Greyhound lacked a policy to remove drivers who repeatedly violated company safety polices,” Michael Fox of the NTSB said.

“This was a terrible tragedy. I hope the folks at Greyhound will take the lessons learned seriously and move forward in, frankly, a much more responsible way in terms of addressing these safety areas we’ve identified in this investigation,” NTSB member Thomas Chapman said.

The NTSB also found probable cause that showed the tractor trailers parked illegally on the shoulder of the exit ramp impeded any chance for the bus to stop or safely return to the roadway. Investigators found the trucks stopped there because of limited parking at the Silver Lake rest area.

“Therefore, staff is proposing a recommendation to the USDOT to pursue available options to increase commercial vehicle parking capacity on highways,” Dan Walsh of the NTSB said.

In a statement, Greyhound told FOX 2 News that it’s “fully cooperated with the NTSB since the beginning of the investigation. As litigation is ongoing, we are unable to comment further at this time.”