Denver International Airport trains were back running normally by noon Friday after a suspected software glitch snarled train operations for more than four hours, delaying planes and causing some passengers to miss flights.
Security screening-line waits, which reached an hour at one point, were back to 10 minutes by 12:09 p.m., and the airport was back to normal, DIA officials said on Twitter.
"Thank you, travelers, for your patience this morning," DIA tweeted.
Problems began at 7:30 a.m. when the trains, which transport passengers to concourses, stopped running for about 35 minutes, said DIA spokeswoman Laura Cole said. Passengers were able to safely exit the stalled trains.
The trains had to be run manually, which slowed operations and reduced train capacity, Cole said.
For a while, train problems forced DIA officials to funnel passengers from the larger terminal screening area to Concourse A screening and then bus passengers to the B and C concourses.
But the terminal screening area reopened about 10:40 a.m. and the bus bridge was dropped.
Cole said some passengers missed connecting flights and some flight departures were delayed .
Cole urged passengers to arrive early at the airport and call their airlines see if their flight is delayed.
Officials are investigating the cause of the train problem, but a software glitch is suspected, she said.