Navigating Denver International Airport means dealing with two completely different transit networks that people constantly confuse: the underground Automated Guideway Transit System moving passengers between the Jeppesen Terminal and Concourses A, B, and C, and the regional RTD A Line commuter train connecting downtown Denver to the airport grounds. Knowing how both operate saves you from missing a flight or waiting unnecessarily on a platform.
The underground airport terminal train runs continuously 24 hours a day, requiring no fixed timetable because cars arrive every couple of minutes. Meanwhile, the commuter rail line from Union Station operates on a scheduled timetable ranging from every 15 minutes during peak hours to every 30 minutes late at night.
Understanding the Underground Terminal Train
The subterranean underground train system is the only way to reach Concourses B and C unless you use pedestrian walkways, which only connect select points. You don't need a schedule for this service.
Frequency and Operating Hours
- Peak hours: Trains cycle continuously with a wait time of under two minutes between arrivals.
- Mid-day and evening: Frequency stays high, rarely exceeding three to four minutes of waiting time.
- Late-night hours: Service scales back to a single shuttle train configuration running back and forth through the tunnels, though it never truly stops.
Route and Stops
The transit system connects four distinct primary stations:
- Jeppesen Terminal (Main Processing): Where you clear security and check bags.
- Concourse A: Accessible via train or the pedestrian skybridge.
- Concourse B: Main hub for major domestic carriers.
- Concourse C: Serves several domestic and international carriers.
If you hear the iconic chime followed by the famous automated voice saying "Please hold on, please," you're experiencing one of the airport's most recognized audio trademarks. Allow boarding passengers to exit completely before pushing onto the car, as crowding the doors creates massive bottlenecks.
Riding the RTD A Line Commuter Train
If you're trying to get from downtown Denver to the airport terminal without dealing with parking fees, the RTD A Line commuter train is your best option. It runs from Denver Union Station straight to the DEN Transit Center, located just outside the main terminal.
Schedule and Timetable
- Peak frequency: Trains depart every 15 minutes from early morning until mid-evening.
- Off-peak and overnight frequency: Trains shift to every 30 minutes outside of peak windows.
- Travel duration: The full trip takes approximately 37 minutes from end to end, making it immune to highway traffic jams on Pena Boulevard.
You can check real-time departures directly through the Regional Transportation District website or transit apps before heading to the platform.
Ticketing and Fares
You can't pay cash on board the train. You must purchase a ticket before stepping onto the platform using ticket vending machines, the RTD Mobile Tickets app, or by tapping a valid contactless credit card or smartphone wallet at the station validators. A standard airport pass covers your entire journey between Union Station and the airport, including any transfers to local light rail lines.
Common Mistakes to Avoid
Travelers often run into preventable issues because they mix up the two transit systems or misjudge timing.
- Mistaking the commuter train for the terminal train: If you are already inside the secure zone looking for your boarding gate, you need the underground terminal train, not the RTD A Line outside.
- Cutting security timelines too close: While the A Line takes precisely 37 minutes, factor in your walk from the platform through the transit center, up into the Jeppesen Terminal, and through security checkpoints, which experience heavy backups during peak holiday rushes.
- Ignoring luggage space: Both trains feature dedicated overhead racks and open floor areas near the doors. Don't block narrow aisles with oversized suitcases.
Frequently Asked Questions
Does the underground airport train run all night?
Yes. The underground transit system operates 24 hours a day, 7 days a week, though it reduces the number of active cars during overnight hours.
How much does the A Line commuter train cost?
A standard one-way ticket between Denver Union Station and the airport costs a flat fee. Check current fare structures on the official Denver International Airport Ground Transportation portal before you travel.
Where do I catch the A Line at the airport?
The station is located on the commuter rail platform directly adjacent to the main Jeppesen Terminal. Follow the overhead signs marked "Transit Center" once you clear baggage claim.
Are pets allowed on the trains?
Pets are welcome on both the RTD A Line and the underground terminal train as long as they stay securely inside approved airline-grade carriers. Service animals are permitted under standard accessibility guidelines.
