What Is the RTD A-Line (University of Colorado A-Line)?
The RTD University of Colorado A-Line— commonly called the DEN A-Line or simply the airport train — is a commuter rail line operated by the Regional Transportation District (RTD) of Denver. It opened in April 2016 and was the first rail connection between downtown Denver and Denver International Airport.
The A-Line runs 23 miles from Denver Union Station in LoDo to Denver International Airport (DEN), making five stops in between. The full trip takes approximately 37 minutes and the train runs nearly 24 hours a day.
A-Line Stations & Schedule
| Station | Travel Time from Union Station | Parking Available | Notes |
|---|---|---|---|
| Denver Union Station | 0 min (start) | Paid garages nearby | LoDo hub; Amtrak, RTD buses, free 16th St Mall shuttle |
| 40th & Colorado | ~7 min | Limited street parking | RiNo / Cole neighborhood connection |
| Central Park | ~12 min | Free park-and-ride lot | Stapleton / Central Park neighborhood |
| Peoria | ~18 min | Free park-and-ride lot | Connection to R, W light rail lines |
| 61st & Peña | ~30 min | $8/day park-and-ride | Closest station to DIA; best for airport parking |
| Denver Airport (DEN) | ~37 min (end) | On-airport parking | Terminal Level 4–5 connection |
Frequency: Every 15 minutes during peak weekday hours (roughly 5 AM–9 PM); every 30 minutesnights and weekends. First departure from Union Station is around 3:00 AM; last departure is around 2:00 AM — covering virtually all flight times.
61st & Peña Station: The Cheapest DIA Parking Hack
The 61st & Peña RTD station is located just 7 minutes from Denver Airport by train and offers a large park-and-ride lot at approximately $8 per day. This makes it the cheapest parking near DIA — less than DIA's Pikes Peak/Longs Peak shuttle lots ($10/day) and dramatically less than the Covered Garage ($35/day, effective May 14, 2025). Source: flydenver.com
The strategy works like this:
- Drive to the 61st & Peña station park-and-ride lot.
- Park your car in the RTD-managed lot (pay at the kiosk or via the MyRTD app).
- Board the A-Line train heading toward Denver Airport (DEN).
- Arrive at the airport terminal in approximately 7 minutes.
- On return: board the A-Line at the airport station, ride back to 61st & Peña, and retrieve your car.
Total door-to-door time from the 61st & Peña lot to the airport terminal is roughly 15–20 minutes including boarding and the train ride — comparable to an off-airport shuttle lot.
Cost Comparison: Driving + Parking vs. Train + Parking
| Option | 1 Night | 3 Nights | 7 Nights | Notes |
|---|---|---|---|---|
| 61st & Peña + A-Line RT | $8 + $21 = $29 | $24 + $21 = $45 | $56 + $21 = $77 | Train fare is always $21 RT regardless of days |
| Off-Airport Lot (Canopy) | $9 | $27 | $63 | Free shuttle; no train ticket needed |
| Off-Airport Lot (Park2Jet) | $9.99 | $29.97 | $69.93 | Free shuttle; no train ticket needed |
| DIA Pikes Peak/Longs Peak (shuttle lot) | $10 | $30 | $70 | Free shuttle; walk-in only; no reservation |
| DIA Covered Garage | $35 | $105 | $245 | Walk to terminal; reservations available |
| A-Line from Union Station RT | $21 train only | $21 train only | $21 train only | For those without a car; add downtown parking/transit |
Bottom line:For 1–2 night trips, the $21 round-trip A-Line ticket erodes the savings from the $8/day parking. For trips of 3+ nights, 61st & Peña parking plus the A-Line becomes competitive with off-airport lots. For trips of 5+ nights, it's often the cheapest option of all.
When to Use the A-Line vs. an Off-Airport Shuttle Lot
- Use the A-Line when: You live near a station (40th & Colorado, Central Park, Peoria), you're traveling from downtown, or you prefer a no-shuttle rail experience with predictable timing.
- Use an off-airport shuttle lot when: You have heavy luggage, you're traveling with children or mobility-limited passengers, or your departure time is very early/late and you want on-demand shuttle rather than a fixed train schedule.
- Use 61st & Peña when: You want the lowest possible parking cost for a multi-night trip and are comfortable with a short 7-minute train connection to the airport.
Luggage Tips for the A-Line
- The A-Line cars have no formal luggage racks but offer generous floor space at the ends of each car — large roller bags store easily.
- During peak hours, trains can be crowded. If you have multiple large bags, board at the front or rear doors where there is more standing room.
- The train platform at Denver Airport connects directly to Level 4–5 of the Jeppesen Terminal via elevator and escalator.
- Allow an extra 5–10 minutes at the airport end to navigate from the train platform to your airline's check-in counter.
- On return, the train platform is accessible from Level 4 (Ground Transportation) — follow “Train to Downtown” signs after exiting baggage claim.
Buying A-Line Tickets
RTD A-Line tickets can be purchased at:
- Station kiosks — Touchscreen machines at every A-Line station accept credit/debit cards and cash.
- MyRTD app — Purchase mobile tickets before you board. Show the active ticket on your phone to fare inspectors.
- RTD.com — Purchase in advance; print or download to your phone.
Note: Unlike some airport trains, the A-Line does nothave a turnstile gate system. Fare inspectors board periodically and check tickets. Always have a valid ticket — fines for fare evasion are $100+.
Frequently Asked Questions
How long does the A-Line train take from Denver Airport to Union Station?
Approximately 37 minutes non-stop end-to-end, or up to 45 minutes with all intermediate stops included in your boarding and alighting time.
How much does the A-Line train cost from DIA?
$10.50 one-way; $21.00 round trip. The fare is the same regardless of which station you board at. An RTD day pass also costs $10.50 and covers unlimited RTD travel for the day.
How much is parking at 61st & Peña station?
Approximately $8 per day. Pay at the station kiosk or via the MyRTD app when you park. Permits are enforced; do not leave your car without paying.
How often does the A-Line train run to Denver Airport?
Every 15 minutes during peak weekday hours; every 30 minutes nights and weekends. The train operates from approximately 3:00 AM to 2:00 AM daily.
Can I bring luggage on the A-Line train?
Yes, no restrictions on luggage size or quantity. Large roller bags fit in the floor spaces at the car ends. Plan for slightly more travel time navigating between the train platform and the terminal.