On the busiest travel days of the year, there used to be only one way to get to Denver International Airport: You had to hit the road.

Most people still do, but this year, an option was the A Line: The trusty Train to the Plane.

Like the roads, the rails were crowded Wednesday.

A spokesman for RTD says the trains were running on time all day.

It's too early to know how many people opted to take the train, but RTD did say it's been busier than normal at Union Station and DIA.

They did suggest passengers allow extra time just in case.

Passengers 9NEWS caught up with at the airport said the A-line was more convenient and cheaper than driving and parking at the airport.