A glitch in a sensor stalled automatic movement on a track carrying passengers from Denver International Airport’s terminal to concourses, resulting in short delays for passengers Saturday and Sunday, Heath Montgomery, DIA spokesman, said Sunday.

The glitch first caused problems on the trains that run to and from three concourses on the day before Thanksgiving, leading the airport to slow lines going through security for about 40 minutes to prevent backups on platforms, Montgomery said.

The sensor malfunctions Saturday and Sunday had less impact on travelers, Montgomery said, with the problems being at least temporarily fixed in 15 to 20 minutes.

“My understanding is we continue to have a sensor malfunction. They are working on a repair. Engineers are trying to figure out why it continues to fail,” he said.

On the day before Thanksgiving, human drivers had to take over trains after a sensor glitch twice stalled automatic movement on one track.

A team of technicians made a temporary fix, and trains that connect the airport’s Jeppesen Terminal to concourses, A, B and C went back into automatic mode.

Later that same morning the problem arose again, and drivers were brought in once more, Montgomery said.

Travelers arriving at Denver International Airport reported massive lines on the platforms. Some got off the train on the A concourse and walked over the skybridge to baggage claim to avoid the crowds exiting the trains in Jeppesen terminal.