PALM SPRINGS, Calif. - The National Transportation Safety Board called Tuesday for federal transportation officials to examine regulations regarding sleep-deprived drivers who work for commercial carriers.
The announcement follows recent determinations that driver fatigue contributed to a Palm Springs freeway crash that killed 13 people and another bus crash in Central California.
The NTSB said the Federal Motor Carrier Safety Administration should reexamine regulations regarding the hours of sleep drivers must have before departing on long trips.
The NTSB's statement was released in conjunction with the board's determination on the cause of an Aug. 2, 2016, crash in which a bus veered off state Route 99 and into a signpost, killing four and injuring 20.
As with the Oct. 23, 2016, Palm Springs crash, NTSB investigators concluded the Livingston crash involved a sleep-deprived driver, who investigators say had slept less than five hours in the previous 40, leaving him in a state of "acute sleep loss."
The NTSB's report on the crash noted similarities to two other fatal bus accidents from 2011, one in New York City that killed 15 and one in Doswell, Virginia, that claimed four lives.
"Here's yet another fatal crash involving both a motorcoach carrier with a starkly evident history of safety problems and a severely fatigued driver," NTSB Chairman Robert L. Sumwalt said. "It's time that the Federal Motor Carrier Safety Administration move more aggressively to keep these unsafe carriers off American roadways."
The NTSB recommended that the FMCSA review its safety rating system for carriers so that more serious sanctions are issued for carriers that commit safety violations. The NTSB argued the FMCSA does not give proper weight to vehicle and driver performance-based data when determining whether a carrier is fit for service.
Under the current system, the bus carrier involved in the Livingston crash, Autobuses Coordinados, received "satisfactory" ratings, despite providing "only the minimum safety management required by the FMCSA to keep its operating authority."
The report did not reference the Palm Springs crash, which the NTSB has said was caused by trucker Bruce Guilford falling asleep at the wheel on Interstate 10, and bus driver Teodulo Elias Vides also likely being sleep-deprived when he crashed into the rear of Guilford's truck at 76 mph.
Vides, who investigators say slept about four hours in the 35 hours preceding the crash, was killed along with a dozen bus passengers.
On the day of the crash, Guilford, 51, was on his second round trip from Eufaula, Alabama, to Salinas within two weeks, according to an arrest warrant declaration. He had previously driven the route from Oct. 8 to Oct. 18, then departed again on a second trip starting Oct. 19.
The nearly nonstop driving Guilford allegedly undertook between Oct. 8 and the Oct. 23 crash "resulted in acute sleep deprivation," according to a declaration prepared by California Highway Patrol Officer Scott Parent.
Of the Palm Springs crash, Sumwalt previously said, "In this crash, not one but two commercial vehicle drivers -- people who drive for a living -- were unable to respond appropriately to cues that other motorists did act on."
Guilford is to be transported to Riverside County from his home state of Georgia to faces more than 40 felony and misdemeanor counts of vehicular manslaughter and reckless driving stemming from the crash.
The bus driver in the Livingston crash, Mario David Vasquez, 58, also faces vehicular manslaughter charges in Merced County.