Train personnel survey the New Jersey Transit train that crashed into the platform at the Hoboken Terminal on Sept. 29, 2016, in Hoboken, N.J. (Pancho Bernasconi/Getty Images)

Two New York-area commuter rail crashes were caused by fatigued engineers suffering from undiagnosed severe sleep apnea, federal safety officials said Tuesday.

A lack of adequate screening for the sleep disorder was cited by the National Transportation Safety Board in its determination of probable cause for the two serious wrecks, and the safety panel renewed its call for the Federal Railroad Administration to make such testing mandatory.

On Sept. 29, 2016, a New Jersey Transit train crashed into the platform at the Hoboken Terminal, killing one person on the platform and injuring 110. The crash also severely damaged the terminal.

On Jan. 4, 2017, a Long Island Rail Road train crashed in the Atlantic Terminal in Brooklyn, injuring more than 100 people.

In both incidents, the trains struck end-of-track bumping posts and ran into stations.

If both railroads had had effective sleep apnea testing programs, “it would have been unlikely that these employees would have been operating trains with undiagnosed and untreated obstructive sleep apnea,” the NTSB report said.

The FRA last year abandoned a proposal that would have required railroad engineers to be tested for the disorder that can cause people to fall asleep on the job. Advocates of the testing, including the NTSB, denounced the decision, which was part of President Trump’s effort to reduce federal regulations.

“The failure of the Federal Railroad Administration to adequately address the issue of employee fatigue due to obstructive sleep apnea and other sleep disorders, most recently evidenced by the August 2017 withdrawal of the advance notice of proposed rulemaking, jeopardizes public safety,” the NTSB said in the report released Tuesday as part of its findings in the New York-area rail crashes.

“The traveling public deserves alert operators,” NTSB Chairman Robert L. Sumwalt said in a statement. “That is not too much to ask.”

An FRA spokeswoman said in a emailed statement that the agency “continues to work closely with the National Transportation Safety Board (NTSB) and will review their recommendations thoroughly.”

The NTSB also recommended the use of technology, such as the automatic braking system known as positive train control (PTC), in terminal stations and improving the effectiveness of system safety program plans to improve terminal operations.

PTC was originally mandated to be in place by the end of 2015, but after a push by the railroad industry, Congress postponed the deadline until the end of this year, with the possibility that it could be extended to the end of 2020.

More than 25 million Americans are estimated to suffer from undiagnosed sleep apnea. The disorder results in the reduction or cessation of breathing during sleep.

The NTSB says sleep apnea has been the probable cause of 10 highway and rail crashes in the past 17 years, including a December 2013 commuter rail crash in New York that killed four people and injured 70.  The NTSB concluded that the engineer fell asleep just before taking a 30-mph curve at 82 mph.

The agency faulted New Jersey Transit for not following its sleep apnea guidelines and blamed the Long Island Rail Road for not having testing in place before the crashes. Investigators also said the safety programs at both rail systems were ineffective in identifying operations hazards in terminal tracks.

NJ Transit had a sleep apnea screening program at the time of the Hoboken crash, but engineer Thomas Gallagher’s most recent available screening form was from 2013, and he wasn’t referred for a sleep study despite displaying some of the necessary criteria, according to testimony in Tuesday’s NTSB report.

The LIRR, operated by the Metropolitan Transportation Authority, embraced its screening program after the crash. Nearly 10,000 employees have been screened, more than 2,000 have been referred for sleep studies and about 1,185 have been diagnosed with sleep apnea and are in treatment, a spokesman said.

“The MTA has an established and aggressive sleep apnea screening and treatment program for all train and bus operators and locomotive engineers in line with the NTSB’s recommendations and we are moving forward with this program, even in the absence of a federal mandate,” MTA spokesman Aaron Donovan said Tuesday.

NTSB’s complete report on the crashes will be available in several weeks.