A Line (RTD)

The A Line,[1] officially called the University of Colorado A Line for sponsorship reasons,[6] is a Regional Transportation District (RTD) commuter rail line serving Denver and Aurora, Colorado, operating between Downtown Denver and Denver International Airport (DIA).[7] During planning and construction the A Line was also known as the East Rail Line, which it is now infrequently called. Most locals refer to it as simply the A Line.[8] Despite its official title, the line does not serve the campuses of the University of Colorado.

A Line
A Line logo.svg
Denver Airport Station, 4028, 16-04-23.jpg
A Line train at the Denver Airport station
OwnerRegional Transportation District
LocaleDenver metropolitan area
TerminiUnion Station
Denver Airport
WebsiteOfficial website
TypeCommuter rail
SystemRegional Transportation District
Operator(s)Denver Transit Partners[2]
Rolling stockHyundai Rotem Silverliner V
Daily ridership20,600 (2019)[3]
Ridership7,042,000 (2018, annual)[4]
OpenedApril 22, 2016 (2016-04-22)
Line length23.5 mi (37.82 km)
Track gauge4 ft 8 12 in (1,435 mm) standard gauge
ElectrificationOverhead lines, 25 kV AC[5] 60 Hz
Route diagram

Denver Airport Denver International Airport
Fare Zone Boundary
61st & Peña
40th Ave & Airport Blvd–Gateway Park
Fare Zone Boundary
Central Park
Fare Zone Boundary
SH 2 (Colorado Boulevard)
40th & Colorado
38th & Blake
 L  (TBD)
 B  G  N 
Union Station
Amtrak  B  G  N 
 C  E  W 


Mass transit has been under consideration for the corridor between Downtown Denver and Denver International Airport since the latter was proposed in the 1980s. The project gathered momentum in 1997 when a Major Investment Study was completed for the corridor, encouraging fixed-guideway mass transit (light rail or commuter rail), highway widening and general improvements. The project was approved as part of the FasTracks transit expansion package in November 2004, went through regulatory processes and was approved by the Federal Transit Administration in November 2009.[9] In July 2007, it was decided to use electric instead of diesel propulsion over speed and air pollution concerns.[10]

RTD designated the line with the letter “A”, denoting service to the airport and Aurora. Groundbreaking for the A Line was held on August 26, 2010.[11] As the second line of RTD’s FasTracks expansion plan, the East Corridor was constructed and operated under the Eagle P3 public–private partnership.[2] The first electric multiple unit railcars were pulled along the route on April 3, 2015, commencing testing and commissioning of the line.[12]

Revenue service began on April 22, 2016.[7][13] A software problem in the equipment closing the crossing gates has resulted in the use of traffic guards and frequent delays since the opening,[14] earning the project a slot on Westword's 2016 Colorado Hall of Shame.[15]

Operational issuesEdit

Since the A line's opening in April 2016, it has had a number of operational issues. The main issue is with the crossing gate technology. Crossing arms have been coming down too early and staying down too long, causing traffic backups. Today, RTD is making progress in fixing the crossing gate timing system along the A line. The A line shares crossings with Union Pacific tracks. This adds complexity to the crossing gate programs and technology.

In June 2018, the FRA approved a plan to remove the flaggers monitoring the crossing gates along the A line. This approval also allows local jurisdictions to submit requests to the FRA to establish "quiet zones", removing the need for trains crossing through the gates to blow their horns.[16]


The A Line route follows and remains within a mile of Interstate 25, Interstate 70, and the airport access highway (Peña Boulevard). The line makes use of a preexisting Union Pacific Railroad right-of-way along the portion of the route from downtown Denver heading east, then deviates to the north along Peña Boulevard in newly created right-of-way. Peña Boulevard was designed with an extra wide median between its inbound and outbound lanes that could have been used for rail transit, though ultimately the East Rail Corridor alignment was offset from the highway right-of-way.

Leaving Union Station the line follows the Union Pacific corridor past Coors Field to reach a station at 38th and Blake Streets shared with the future Central Corridor expansion. From there the line turns east alongside 40th Avenue past the Denver Union Pacific Intermodal Yard. Just east of Josephine Street the corridor turns two blocks north then east again to stay along the Union Pacific corridor to reach the 40th Avenue and Colorado Boulevard station. After passing under Colorado Boulevard the line parallels Smith Road, with a station at Central Park Boulevard in the redevelopment area of the decommissioned Stapleton International Airport. Shortly after entering Aurora, the line reaches a station at Peoria Street, which will be shared with the new R Line. Continuing east, alongside Smith Road, the line passes under Peoria Street and then Interstate 225. Just west of Airport Boulevard, the line rises on a viaduct curving north over the Union Pacific tracks, Airport Boulevard, 32nd Avenue, and Interstate 70. Having left the Union Pacific corridor, the viaduct then descends to a station at the existing Park and Ride at 40th Avenue and Airport Boulevard. From there the line reenters Denver, following the east side of Peña Boulevard. North of 56th Avenue it enters an added to the line construction[17] Peña Boulevard[1] station at 61st Avenue.[18][19] The line continues north and east, parallel to Peña Boulevard and crossing over E-470. Turning north, the line crosses over Peña Boulevard adjacent to DIA runway 7/25 and then runs east between the airport secure area and 78th Avenue. The line then crosses over the south/west terminal exit lanes of Peña Boulevard ending at a station on the south side of the DIA Hotel and Transit Center, itself at the south end of the DIA Jeppesen Terminal.[20][21]


Name Opening Year Interchange Municipality Park & Ride
A Line (Union Station – Denver Airport)
Union Station 2014  B ,  G  &  N  Lines
 C ,  E , &  W  Lines
FREE MallRide (16th St)
Denver No
38th & Blake 2016 Proposed  L  Line Denver Yes (200)
40th & Colorado 2016 None Denver Yes (200)
Fare Zone Boundary
Central Park 2016 None Denver Yes (1,500)
Peoria 2016  R  Line Aurora Yes (550)
Fare Zone Boundary
40th Ave & Airport Blvd–Gateway Park 2016 None Aurora Yes (1,079)
61st & Peña[23][24] 2016[1] None Denver Yes (800; private lot)
Fare Zone Boundary
Denver Airport 2016 None Denver No


  1. ^ a b c d "RTD - A Line". RTD - A Line. Regional Transportation District. Retrieved June 21, 2015.
  2. ^ a b "Eagle P3 Commuter Rail Project, Denver, USA". Railway Technology. Archived from the original on September 12, 2011. Retrieved September 1, 2011.
  3. ^ Aguilar, John (May 2, 2019). "A-Line marks 20 million passengers since train to Denver International Airport opened in 2016". Denver Post. Retrieved August 27, 2019.
  4. ^ "RTD Monthly Financial Report" (PDF). RTD. December 30, 2018. Retrieved March 23, 2019.
  5. ^ "Commuter train testing begins on G Line". RTD FasTracks. Regional Transportation District of Denver. Retrieved July 25, 2016.
  6. ^ Harden, Mark (August 19, 2015). "The A line goes to college: CU pays $5 million for RTD airport-rail naming rights". Denver Business Journal. Retrieved February 29, 2016.
  7. ^ a b "RTD - East Rail Line". Regional Transportation District. Retrieved April 29, 2015.
  8. ^ "Stories Along the Line: East Rail to roll on historical ground". www.rtd-fastracks.com. Retrieved May 3, 2017.
  9. ^ "Fastracks - East Corridor". Regional Transportation District. Retrieved April 29, 2010.
  10. ^ "Electric Multiple Unit" (PDF). East Corridor Environmental Impact Statement. Archived from the original (PDF) on November 20, 2008. Retrieved July 23, 2014.
  11. ^ "East Corridor Groundbreaking!". Denver Infill Blog. Archived from the original on September 12, 2011. Retrieved July 26, 2010.
  12. ^ "Denver's new EMUs take "maiden voyage"". Railway Age. Retrieved April 7, 2015.
  13. ^ "RTD service from Union Station to DIA scheduled to start April 22". The Denver Channel. Archived from the original on October 24, 2015. Retrieved October 22, 2015.
  14. ^ "Feds give RTD another 90 days fix A-Line crossing problems – The Denver Post". Retrieved February 6, 2017.
  15. ^ http://www.westword.com/news/the-eight-inductees-into-the-2016-colorado-hall-of-shame-8622104
  16. ^ "A-Line's noisy train horns' days are numbered, as RTD plans to pull flaggers back from six crossings starting Friday". The Denver Post. Retrieved July 19, 2018.
  17. ^ "New train station part of East Rail". rtd-fastracks.com. Regional Transportation District. Retrieved August 20, 2015.
  18. ^ Hodes, David. "Colorado Experiences Phenomenal Success (with Photo)". Business Xpansion Journal. Retrieved June 15, 2015.
  19. ^ "Eagle P3 Project update", Fast Tracks Monitor Committee, May 13, 2014
  20. ^ "Hotel and Transit Center". FlyDenver.com. Archived from the original on July 2, 2015. Retrieved May 31, 2010.
  21. ^ "Appendix A Preferred Alternate Maps" (PDF). East Corridor Environmental Impact Statement. Retrieved April 29, 2010.[dead link]
  22. ^ "University of Colorado A Line Stations & Parking". RTD. Retrieved April 23, 2016.
  23. ^ "Peña Station Rail Stop", Flydenver.com, 2015
  24. ^ "61st & Peña Station Area Plan" Archived June 21, 2015, at the Wayback Machine, City and County of Denver, January 13, 2014

External linksEdit

Route map:

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