Facts & Stats: Everything You Should Know About Denver’s Airport Train

A passenger prepares to board an RTD A-Line train at Union Station on January 30. Streetsblog file photo by Andy Bosselman.
A passenger prepares to board an RTD A-Line train at Union Station on January 30. Streetsblog file photo by Andy Bosselman.

Facts & Stats is a new Streetsblog Denver series that looks at walking, biking and transit through the lens of data and statistics.

Correction: This article has been corrected to reflect correct ridership numbers from 2016 and 2017, which shows a steady increase in A-Line ridership, not a decrease. The error was due to incorrect information provided by RTD.  

In this story, we look at the cost, route, ridership numbers, vehicles, station design and other issues related to the Regional Transportation District’s second-newest railroad, the train between Union Station and Denver International Airport.

Of the many data points collected here, a sharp decline in ridership stands out: In 2016, the A-Line carried 35% more passengers during its first eight months of operation than it did in all of 2018.

RTD is the source of information, unless otherwise noted.  

University of Colorado A-Line to DIA


  • 7 million: Boardings in 2018 (6% increase)
  • 6.6 million: Boardings in 2017
  • 4.1 million: Boardings in 2016 (service started April 22)


  • $1.2 billion: Construction cost (Denver Post)
  • $52 million: Cost per mile ($32 million cost per km) (Streetsblog)
  • $62,202: Capital cost per passenger (based on 2018 daily boardings) (Streetsblog)
  • $10.50: Regular adult fare
  • $5 million: Amount the University of Colorado paid to name the line after itself, even though the route does not come near any of its four campuses. (Denver Post)
  • Yes: Voter-approved FasTracks project
A map of RTD's University of Colorado A-Line route.
A map of RTD’s University of Colorado A-Line route.


  • 23 miles (37 km): Length
  • 7: Stations
  • 4,329: Parking spaces at stations along the line with another 4,371 planned


  • 37 minutes: Time it takes to get between Union Station and DIA
  • 15 minutes: Frequency of service 7 days per week
  • 30 minutes: Frequency of service for early morning and late evening trips
  • 97%: On-time performance rate (Denver7)


  • 170: Maximum passengers per car
  • 79 mph: Maximum speed
  • Rolling stock: Hyundai Rotem Silverliner V (Wikipedia)
  • AC electric overhead wire: Vehicle power source
  • Standard: Rail gage
A rendering of the Denver Airport Station by architect Santiago Calatrava. Calatrava abandoned the project in 2011.
A rendering of the Denver Airport Station by architect Santiago Calatrava. Calatrava abandoned the project in 2011.

Station design

  • Denver commissioned Santiago Calatrava, a Spanish architect known for creating stellar bridges and rail stations around the world, to design Denver Airport Station. Calatrava withdrew from the project in 2011, citing a lack of funding and an unrealistic schedule (Denver Post). Gensler completed the project, along with the adjoining Westin hotel (Gensler). Calatrava was one of several high-profile architects whose projects failed to materialize under the leadership of then-mayor John Hickenlooper (Streetsblog).
  • At Union Station, the global architecture firm SOM designed the open-air Train Hall, Light Rail Terminal and 22-gate underground Bus Concourse (SOM).
  • The local firm Tryba Architects oversaw Union Station’s renovation (Tryba Architects).

Commuter vs. light rail

Commuter rail is relatively new to RTD, with its first route, the A-Line to the Denver International Airport, opening in April 2016, and its second, the B-Line from Union Station to Westminster, opening in July of that year.

RTD operates two types of trains. The familiar light rail vehicles, which have run in the city since 1994, and commuter rail vehicles, which are heavier, carry more passengers, can travel at higher speeds and generally go longer distances between stops.

Crossing gate problems

In November, the Federal Railroad Administration threatened to shut down the A-Line over crossing arms that fail to lower and raise at precise times before and after trains cross intersections (CPR), a problem that has existed since the line first opened. RTD employed human flaggers instead. 

The RTD A, B, G and N-Lines are the first newly constructed rail lines in the U.S. to integrate Positive Train Control systems, which use GPS and other technologies to monitor vehicles. The system can slow or stop trains to prevent wrecks — and it triggers the crossing signals.

RTD and its private partner have struggled to get the crossing arms to work properly. In December RTD scrambled to come up with a plan to fix the crossing gate issue by 2020. RTD presented the plan to the FRA that month and FRA allowed the A-Line to continue operating. Soon after, the FRA allowed RTD to stop using flaggers (Denver Post). Earlier this month, RTD showed another sign of progress when it announced that the FRA would stop requiring A-Line trains to blow its horns at every intersection within Denver.

Eagle P3 Public Private Partnership

FasTracks A and G-Lines and first segment of the B-Line are part of a public-private partnership called Eagle P3. The private entity, known as Denver Transit Partners, provided some money to fund the projects in exchange for RTD paying it to run and maintain the lines over 34 years.

DTP and RTD are suing each other over delays, withheld payments, and the cost of paying human flaggers (CPR).

Are their local transportation Facts & Stats you’d like to know? E-mail andy@streetsblog.org.

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