By Raetta Holdman

DENVER (CBS4) – A failed hub in a wheel on one of the underground trains at Denver International Airport caused the massive disruption that affected thousands of travelers last month. It happened just after midnight on Aug. 20 and ultimately led to extremely long security lines and flight delays.

(credit: Denver International Airport)

The airport on Thursday sent out pictures of the damaged wheel and the damage it did to the tracks. The failure tripped a circuit breaker which led to power issues.

(credit: Denver International Airport)

Approximately 200 people were on the train at the time of the failure and walked out of the tunnels to get to their location.

(credit: Denver International Airport)

(credit: Marcus Simmons)

The train car involved had been in service for 20 years but was inspected 2 months before.

When the hub failed, the wheel was locked in place even though the train was still running. That wore the rubber off the wheel while the train was running which in turn damaged about 100 feet of track that had to be replaced between Concourse A and the terminal.

(credit: Denver International Airport)

It took crews about 11 hours to get the trains back online. That led to hundreds of missed flight connections.

DIA officials say a full inspection of the rest of the underground trains is taking place. After August’s failure, they said they’re “committed to exploring options to provide alternate ways to move passengers between the terminal” and the concourses.

Raetta Holdman