DENVER (CBS4) – People will have some terrible travel stories to tell at the dinner table this Thanksgiving.

The concourse trains that run underground malfunctioned at Denver International Airport two different times Wednesday morning. A sensor fault meant the trains couldn’t operate on certain sections of the track. Airport officials said it was the first time a malfunction like this has happened, and it just happened to be on one of year’s busiest travel days.

“We’ve identified what happened and so they’re going to be troubleshooting why that happened and how they can prevent it from happening again,” said DIA spokesman Heath Montgomery. “We’ve never had this particular issue with the train system before, so it’s something new that happened this morning.”

As a result of the problem, technicians had to switch to a manual bypass mode so the trains could go around where the sensor fault areas were. The Transportation Safety Administration also had to shut down all but one or two their security lines because of the congestion.

One traveler told CBS4 she waited 20 minutes for the train to arrive, then she waited for 10 minutes at every stop.

Most of the passengers who were running late to their departure gates were able to make their flights because a lot of airlines delayed departure times to accommodate them.

RELATED: Concourse Trains Issue Just One Of Several Morning Travel Issues

Officials warned that travelers should plan to arrive at the airport at least two hours ahead of their flight time to assure they will get out on time during this busy holiday travel period.