Angela Greiling Keane
Bloomberg News

Investigators’ conclusion that both operators of a Burlington Northern Santa Fe freight train fell asleep before a fatal wreck last year revived concerns that led to rules restricting hours of airline pilots and truck drivers.

“Once again, this investigation draws attention to the dangers of human fatigue,” National Transportation Safety Board Chairman Deborah Hersman said in a statement.

Both operators of a coal train that struck the back of another Burlington Northern train that was stopped near Red Oak, Iowa, on April 17, 2011, fell asleep and missed signals to slow and stop, the safety board found. The tracks didn’t have crash-avoidance technology that U.S. railroads must install by 2015 under a U.S. rule, it said.

Officials at Burlington Northern could not be reached for comment.

About one in four pilots and rail workers surveyed by the National Sleep Foundation reported that sleepiness affects their job performance at least once a week, compared with one in six nontransportation workers, according to a report issued last month.

The U.S. introduced pilot-scheduling regulations designed to limit fatigue that take effect in December 2013. The rules reduce hours passenger-airline pilots can work late at night, after crossing numerous time zones or making numerous landings and takeoffs.

The Department of Transportation in December backed off proposed rules that would have reduced the maximum driving day for truckers to 10 hours, from 11, while requiring a 34-hour rest period each week that would require drivers to be off two consecutive nights.

The trucking industry has challenged the rule in court.