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A Line
A Line train at the Denver Airport station
Overview
OwnerRegional Transportation District
LocaleDenver metropolitan area
Termini
Stations8
WebsiteOfficial website
Service
TypeCommuter rail
SystemRTD Rail
Operator(s)Denver Transit Partners[1]
Rolling stockHyundai Rotem Silverliner V
Daily ridership20,600 (2019)[2]
Ridership6,184,000 (FY2023, annual)[3]
History
OpenedApril 22, 2016; 9 years ago (2016-04-22)
Technical
Line length23.5 mi (37.82 km)
Track gauge4 ft 8+1⁄2 in (1,435 mm) standard gauge
ElectrificationOverhead line, 25 kV 60 Hz AC[4]
Route map
Map
A Line highlighted in blue
Legend
 Denver Airport Denver International Airport
E470.svg E-470
Fare Zone Boundary
 61st & Peña
40th Ave & Airport Blvd–Gateway Park
I-70.svg I-70
I-225.svg I-225
 Peoria
to Lincoln
 Central Park
Colorado 2.svg
SH 2
Colorado Boulevard
 40th & Colorado
38th & Blake
Amtrak Amtrak California Zephyr
 Union Station
Amtrak
This diagram:

The A Line (formerly the University of Colorado A Line for sponsorship reasons)[5] is a Regional Transportation District (RTD) commuter rail line serving Denver and Aurora, Colorado, operating between downtown Denver and Denver International Airport (DIA).[6] During planning and construction, it was also known as the East Rail Line, but most locals refer to it as the A Line.[7] Despite its former title, the line does not serve the campuses of the University of Colorado.

History

[edit]

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.[8] In July 2007, it was decided to use electric instead of diesel propulsion over speed and air pollution concerns.[9]

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.[10] As the second line of RTD's FasTracks expansion plan, the East Corridor was constructed and operated under the Eagle P3 public–private partnership.[1] The first electric multiple unit railcars were pulled along the route on April 3, 2015, commencing testing and commissioning of the line.[11]

Revenue service began on April 22, 2016.[6][12]

From the A line's opening in April 2016 and until mid-2018, there have been operational issues with the crossing gates due to software problems, resulting in frequent delays. Crossing arms have been coming down too early and staying down for too long, and did not react dynamically to variance in arrival and departing times.[13] Westword listed the project on its 2016 Colorado Hall of Shame.[14] The A Line shares crossings with Union Pacific tracks, adding to the complexity to the crossing gates.

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.[15] As of February 2019, approval for "quiet zones" at nine of the line's crossings has been granted, to be in effect on March 1, 2019; see Normal Whistle Codes.[16]

Route

[edit]

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 a 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 Peoria station, which is shared with the 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[18] station at 61st Avenue.[19][20] 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.[21][22]

Stations

[edit]
Fare
zone 		Station Municipality Opened Major connections & notes
Local Union Station Denver April 22, 2016
California Zephyr
Bus interchange MallRide
38th & Blake Park and ride: 200 spaces
40th & Colorado Park and ride: 200 spaces
Central Park Park and ride: 1,500 spaces
Peoria Aurora
Park and ride: 550 spaces
40th Ave & Airport Blvd–Gateway Park Park and ride: 1,079 spaces
61st & Peña[23][24] Denver Parking: 800 (paid)
Airport Denver Airport Airport interchange Denver International Airport

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

A Line (RTD)

View on Grokipedia
from Grokipedia
The A Line is an electrified line operated by the (RTD) in the of , , connecting Denver Union Station in to Denver International Airport over a distance of 23 miles with eight stations and a typical end-to-end travel time of 37 minutes. It serves primarily the cities of and Aurora, offering direct airport access as a key component of the region's public transit network, and carried approximately 5.9 million passengers in 2024. Planning for the A Line began in 1997 as part of RTD's broader rail expansion efforts, but it was formalized under the voter-approved program in 2004, which aimed to build 122 miles of new rail lines across the metro area. The line's development proceeded through the Eagle P3 public-private partnership, which included a $1.03 billion grant from the in 2011 to fund construction. Construction faced delays due to coordination with airport infrastructure and safety enhancements, but the line officially opened to the public on April 22, 2016, marking the completion of the first FasTracks rail corridor. Often described as the "jewel in the crown" of the RTD system, it utilizes Hyundai Rotem Silverliner V two-car trainsets powered by 25 kV 60 Hz AC overhead , with each train accommodating up to 300 seated passengers and 100 standing. The route runs northeast from Union Station along the and through industrial and residential areas, stopping at 38th & Blake Station, 40th & Colorado Station, Central Park Station, Peoria Station, 40th Avenue & Airport Boulevard/Gateway Park Station, and 61st & Peña Station before reaching terminal. Service operates daily from approximately 3:00 a.m. to 12:30 a.m., with headways of 15 minutes during peak hours (4:30 a.m. to 6:30 p.m.) and 30 minutes otherwise, extending to a 1:00 a.m. round trip on Fridays and Saturdays; trains may run longer consists for special events. The line integrates with RTD's broader network at Union Station, providing seamless transfers to other rail lines (such as B, D, E, G, N, , and ), light rail, and bus routes, while offering 4,500 parking spaces across its stations to support commuter access. Notable features include the establishment of quiet zones at all eight stations in 2019 to reduce train horn usage in residential areas, contributing to high on-time performance of 93.3% and service availability of 98.1% in 2024. Ridership has grown steadily post-opening, peaking at 7.87 million in 2019 before declining during the to 3.77 million in 2020, and recovering to 6.18 million by 2023. As a critical link for travelers and regional commuters, the A Line enhances connectivity in the area, reducing reliance on roadways like Peña Boulevard and supporting around its stations.

Overview

Description and purpose

The A Line is a 23-mile electric line operated by the that runs from Union Station in to the . This service forms a key component of RTD's rail network, offering a direct link between the urban core and one of the nation's busiest airports. The primary purpose of the A Line is to facilitate efficient airport access for commuters, travelers, and regional visitors, while contributing to broader efforts to reduce road congestion on major corridors such as Peña Boulevard and by providing a reliable public transit alternative. As part of the voter-approved expansion program initiated in 2004, the line aims to enhance overall mobility in the , promoting sustainable transportation options and integrating with the growing demands of and urban development. The A Line opened on , 2016, marking a significant milestone in the initiative. It operates daily from approximately 3:00 a.m. to 12:30 a.m., with frequent service including 15-minute headways during peak hours from 4:30 a.m. to 6:30 p.m. and 30 minutes otherwise, extending to a 1:00 a.m. round trip on Fridays and Saturdays, completing the end-to-end journey in approximately 37 minutes. At Union Station, it seamlessly connects with other RTD rail lines, such as the B, D, E, F, G, L, N, R, and W lines, enabling easy transfers and supporting integrated regional transit.

Specifications

The A Line spans a total route length of 23 miles from Denver Union Station to Denver International Airport. It features eight stations along its path, providing key connectivity points for commuters and airport travelers. The infrastructure adheres to standard gauge track measuring 4 ft 8 + 1⁄2 in (1,435 mm), consistent with American commuter rail standards. Electrification is supplied via 25 kV 60 Hz AC overhead catenary, enabling efficient electric operation across the line. The maximum operating speed reaches 79 mph, supporting a typical end-to-end travel time of approximately 37 minutes. The line's profile includes a maximum grade of 3.6% as it approaches the airport, within the design limits for dedicated commuter rail track allowing up to 4% absolute maximum. Stations collectively offer about 4,500 parking spaces to accommodate park-and-ride users. The consists of (EMU) vehicles, specifically Hyundai Rotem V cars operating in married pairs or consists of up to four cars, each with 91 seats and a total capacity of 170 passengers including standees.
SpecificationDetails
Route Length23 miles
Number of Stations8
Maximum Speed79 mph
Electrification25 kV 60 Hz AC overhead catenary
Track Gauge4 ft 8 + 1⁄2 in (1,435 mm)
Maximum Grade3.6% (approaching DIA)
Parking Capacity~4,500 spaces
Vehicle TypeElectric multiple units (EMU)

History

Planning and funding

The planning for a rail connection between and (DIA) originated in the 1980s, as the (RTD) and the City and County of Denver conducted studies amid regional economic challenges from the 1983 oil bust and air quality issues associated with the "Brown Cloud" pollution. These early efforts focused on regional and options, identifying Union Station as a potential multimodal hub and proposing service to the then-proposed DIA to address growing transportation needs. The project gained momentum through inclusion in RTD's FasTracks program, a comprehensive transit expansion initiative placed on the ballot in 2004. Voters in the eight-county RTD district approved the measure on November 2, 2004, by a 58% to 42% margin, authorizing a 0.4% increase in the regional sales and —from 0.6% to 1.0%—to generate dedicated funding for FasTracks, originally estimated at $4.7 billion. This tax increase was projected to raise approximately $6.5 billion over 12 years to support 122 miles of new rail, including the 23-mile East Corridor line to DIA, which would become the A Line. Funding for the A Line specifically drew from multiple sources within the framework, including approximately $450 million in bonds backed by revenues, a $90 million federal New Starts grant awarded in 2009, and direct RTD contributions from existing reserves and tax collections. These resources covered the project's estimated $453 million , with the federal grant supporting design and environmental compliance while bonds and RTD funds handled construction and right-of-way acquisition. The program as a whole supplemented local revenues with over $1 billion in federal grants and loans by 2010, though the A Line's allocation emphasized its role as a high-priority link. Between 2005 and 2008, RTD and the () prepared environmental impact statements (EIS) for the East Corridor, evaluating multiple alignments amid debates over community impacts, freight compatibility, and cost efficiency. Stakeholders, including local governments and environmental groups, contested options such as highway-adjacent paths versus rail corridors, ultimately selecting the (UP) corridor for its existing infrastructure and lower disruption potential; the Draft EIS was released in 2008, with the Final EIS approved by the RTD Board in May 2008. This decision facilitated shared use of the UP right-of-way while addressing concerns like , , and wetland preservation through measures. To secure access, RTD negotiated a partnership with Union Pacific, culminating in a 2009 agreement to purchase approximately 19 miles of right-of-way along the corridor, granting perpetual for passenger rail operations alongside freight traffic. This deal, finalized after earlier stalled talks over pricing and additional land needs, resolved key access barriers and enabled the project's advancement under oversight.

Construction and opening

Construction of the A Line, officially known as the , commenced with a groundbreaking ceremony on August 26, 2010, led by the (RTD) and its design-build-operate-maintain contractor, Denver Transit Partners, under the Eagle P3 public-private partnership. The project encompassed approximately 23 miles of dedicated track from Union Station in to , including the construction of seven new stations, electrification infrastructure, and integration with the existing rail network along the Union Pacific corridor. Last rail was laid in 2014, marking the completion of major trackwork. The timeline faced significant delays due to the complexities of implementing Positive Train Control (PTC), a federally mandated safety system designed to prevent collisions and overspeed incidents, which extended the projected opening from an initial target of late to April 2016. Testing and commissioning, including safety certification for PTC, began in , with initial low-speed runs in and progression to full-speed trials at up to 79 mph by . Full revenue service launched on April 22, 2016, providing 15-minute peak-hour frequencies between the airport and downtown. Early operations encountered challenges, particularly with grade crossing gate timing at shared Union Pacific intersections, necessitating flaggers at several locations from May 2016 onward to ensure safety. These issues were resolved by 2018, allowing RTD to remove flaggers from six key crossings after Federal Railroad Administration approval of improved signal synchronization. Persistent horn usage at crossings due to gate malfunctions led to resident complaints, prompting the establishment of quiet zones along the corridor effective March 1, , following FRA waivers that permitted reduced horn sounding at compliant intersections. Ridership initially ramped up gradually amid these teething issues, with on-time performance improving from 87 percent in the first nine months to over 90 percent by 2017 as reliability stabilized. The total project cost for the East Corridor reached approximately $1.2 billion, incorporating infrastructure upgrades, vehicle procurement, and PTC installation, financed through a $1.03 billion federal Full Funding Grant Agreement awarded in 2011, supplemented by local revenues from the program.

Route and infrastructure

Alignment and path

The A Line originates at Union Station in and proceeds northeast along the corridor through urban and industrial neighborhoods to the vicinity of 38th Street and Blake Street. This initial segment utilizes existing rail corridors in a densely developed area, transitioning from city streets to dedicated rail alignment near the 40th Street and Boulevard station. From there, the route shifts eastward, following the freight corridor parallel to through the suburbs of and Aurora, before turning north toward (DIA). This middle portion, which constitutes the majority of the 23-mile route, operates on tracks built within the preexisting Union Pacific right-of-way, with new adding and double-tracking to support passenger service. The alignment remains largely flat but includes gradual elevation gains typical of the Denver plains. The final segment diverges from the freight corridor onto a dedicated right-of-way along Peña Boulevard, providing a direct approach to the DIA terminals. This approximately 5-mile extension features new trackage designed exclusively for , ensuring seamless integration with infrastructure. The entire route employs a double-track configuration to enable 15-minute headways, with elevation rising from approximately 5,187 feet at Union Station to 5,434 feet at DIA.

Signals and grade crossings

The A Line employs (PTC), a federally mandated system designed to enhance operational security on shared corridors. Implemented as one of the first new PTC installations in the United States upon the line's 2016 opening, the system utilizes GPS and wireless technology to monitor train locations in real time, automatically enforcing speed restrictions and preventing collisions by alerting operators or initiating emergency stops if hazards are detected. PTC on the A Line also protects against derailments from excessive speeds, unauthorized movements into occupied sections, and incursions into maintenance zones, with the capability to automatically slow or halt trains after an 8-second operator response window. While primarily focused on train-to-train interactions and route protection, the system's integration with wireless grade crossing warnings supports broader trespasser detection by flagging potential intrusions along the right-of-way. The A Line features 12 at-grade crossings, concentrated in its urban segments between Union Station and Station, where street-level intersections with vehicle and pedestrian traffic necessitate robust warning infrastructure. These crossings were upgraded in 2018 to address early operational issues, including unreliable gate activation that had prompted constant horn use; improvements included the installation of four-quadrant at select locations to fully block all approach and prevent vehicles from bypassing lowered arms. Pedestrian safety enhancements at these sites incorporated swing , channelized fencing to direct foot traffic to designated crosswalks, and barriers such as medians and gate arms to deter unauthorized pathfinding, aligning with (FRA) standards for supplementary safety measures. By March 2019, all 12 crossings qualified as quiet zones under FRA exemptions to the routine horn rule, allowing trains to operate without sounding horns except in emergencies, thereby reducing noise impacts in adjacent residential areas while maintaining safety through the upgraded gates and barriers. These designations followed diagnostic testing and FRA approvals, with initial certifications for nine crossings in early 2019 and the remainder shortly thereafter. The A Line shares trackage rights with (UP) freight operations along much of its route, necessitating close coordination through RTD's Rail Operations Control Center and UP dispatchers to sequence movements and avoid conflicts. This integration ensures real-time communication for track access, signal prioritization, and emergency response, complying with interstate commerce regulations for mixed-use corridors. In response to a November 5, 2025, incident at Peoria Station where a trespassing was struck by an A Line train and hospitalized, RTD reinforced ongoing safety protocols, including heightened monitoring via PTC-linked sensors and expanded fencing along vulnerable right-of-way segments to prevent similar unauthorized access. These measures build on RTD's broader investments in surveillance cameras, patrols, and public awareness campaigns to mitigate pedestrian risks on the line.

Stations

Station list

The A Line operates eight stations along its 23-mile route from to , all of which opened for service on April 22, 2016, except for Union Station, which serves as a multi-modal hub since 2014. The stations are listed below in sequence from west to east (Union Station to Denver Airport Station) for eastbound service.
Station NameLocationOpening Date
Union Station2014 (multi-modal hub; A Line service 2016)
38th & Blake StationNear Five Points neighborhood, 2016
40th & Colorado StationGlobeville area, 2016
Central Park StationNear commercial area, 2016
Peoria StationPeoria Street area, Aurora2016
40th Ave & Airport Blvd StationNear Gateway Park, Aurora2016
61st & Peña StationPark-and-ride facility near Peña Boulevard, 2016
Denver Airport StationUnderground at DIA concourse level2016

Facilities and connections

The A Line stations feature a range of passenger amenities designed to enhance and convenience, including ticket vending machines available at all rail platforms for purchasing fares such as 3-hour passes and day passes. Platforms are equipped with shelters for weather protection, and bike racks are provided at select locations to support multimodal trips, while bike lockers are available at key park-and-ride sites. All stations comply with ADA standards, offering elevators, ramps, and accessible pathways to ensure usability for passengers with disabilities. Union Station serves as a major multi-modal transportation hub in , integrating A Line with intercity services, RTD lines (including the E, F, and H Lines), and over 20 bus gates for local and regional RTD bus routes. It lacks dedicated parking facilities due to its urban location but provides seamless connections to taxis, rideshares, and the shuttle for broader access. At the Airport Station, passengers access the underground platform via escalators and elevators from the Denver International Airport's Terminal on Level 5, facilitating direct links to baggage claim, check-in counters, and security screening areas. The station emphasizes accessibility with ADA-compliant features, including wide platforms and , and connects to airport shuttles and RTD SkyRide buses at the adjacent DEN Transit Center. Park-and-ride lots support the A Line with a total of 4,500 spaces across its stations, enabling commuters to drive, , and transfer to rail. The largest facility is at 61st & Peña station, offering 800 paid spaces managed by , with daily rates of $10 and EV charging options available. at other A Line lots, such as those at Peoria and , is generally free for the first 24 hours for in-district vehicles, promoting extended use for airport travel. Transit connections extend beyond rail, with RTD bus routes serving every A Line station for local feeder service. Light rail integrations occur at Union Station and Central Park station, where passengers can transfer to the E Line for northeast corridor access, and at Peoria Station to the R Line. At the airport end, additional shuttles and ground transportation options link to rental cars and off-site parking, streamlining arrivals and departures.

Operations

Service patterns and schedule

The A Line operates daily from approximately 3:00 a.m. to 1:07 a.m., providing service seven days a week with schedules aligned to accommodate early morning and late-night airport flights at . First trains depart Union Station around 3:00 a.m. and the Denver Airport Station around 3:37 a.m. (eastbound), while last trains depart around 12:30 a.m. and arrive at their destinations around 1:07 a.m., with extended service on Fridays and Saturdays. Service follows an all-stop pattern, with trains making scheduled stops at all eight stations along the 23-mile route between Union Station and the Airport Station. Headways are 15 minutes from 3:00 a.m. to 9:37 p.m. on weekdays (–), transitioning to varied intervals thereafter; weekends follow similar patterns with potential adjustments. This frequency supports consistent connectivity to the line's stations. End-to-end travel time is approximately 37 minutes under normal operating conditions, covering the full route without intermediate delays. On major holidays including New Year's Day, Memorial Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day, the A Line follows a reduced Sunday/holiday schedule with adjusted frequencies and potentially fewer trips. Fares for the A Line are integrated into the Regional Transportation District (RTD) system, with a standard 3-hour pass at $2.75 and a day pass at $5.50 applicable outside the airport fare zone. Travel to or from requires an Airport Day Pass at $10 for full-day access, or an upgrade surcharge of $7.25 added to a 3-hour pass and $4.50 to a day pass; discount fares for eligible riders (seniors, people with disabilities, Medicare cardholders) and monthly passes include airport travel at no extra cost.

Rolling stock

The A Line operates using a fleet of V () railcars, with 66 in total serving the Regional Transportation District's network, including the A, B, G, and N lines. These single-level operate in married pairs, where each pair consists of an "A" (positioned at the Union Station end) and a "B" (equipped with a for collecting power from the overhead system). On the A Line, trains typically consist of four (two married pairs) to accommodate demand, particularly for travel. Procurement of the Silverliner V cars was part of the Eagle P3 public-private partnership, with the contract awarded to Denver Transit Partners in 2010 for , , financing, operation, and maintenance of the system. The order for 66 cars, valued at approximately $300 million, was placed with , whose body shells were manufactured in , , and final assembly occurred in . The first cars arrived in on December 3, 2014, with full delivery completed by 2016, enabling revenue service to begin on the A Line in April 2016. Designed specifically for the A Line's service, the cars include features such as oversized vertical luggage racks, overhead bins, and dedicated storage areas for suitcases, strollers, and carry-on items to handle passenger baggage needs. Additional amenities encompass two ADA-compliant spaces per car, accommodations for four bicycles, and wider aisles for improved accessibility and flow. Each Silverliner V car provides 91 seated positions, with a total capacity of 170 passengers including standees, resulting in approximately 300 seated and 100 standing passengers per four-car A Line trainset under peak conditions. The cars measure 85 feet in length, 10 feet 6 inches in width, and 14 feet 8 inches in height, with a curb weight of 146,600 pounds and a top speed of 79 mph. Powered by a 25 kV 60 Hz AC overhead system and a 620-horsepower motor per car, the EMUs support efficient, quiet operation without the need for separate locomotives. Maintenance for the A Line fleet is conducted at the Commuter Rail Maintenance Facility (CRMF) located at 5151 Fox Street in Denver's Globeville neighborhood, which includes service tracks, inspection bays, a truing machine, and storage for the entire fleet. This facility, completed in 2015 as part of the program, handles routine inspections, repairs, cleaning, and heavy overhauls to ensure 98.1% service availability as of 2024. As of November 2025, the average age of the Silverliner V fleet is approximately 9.5 years, reflecting deliveries between 2014 and 2016. The Silverliner V cars are equipped with (PTC) integration, a safety system deployed across the A Line to prevent collisions, derailments, and incursions into work zones, making RTD the first U.S. transit agency to implement PTC from the ground up on a new rail line. As electric vehicles drawing power from , they produce zero tailpipe emissions and comply with U.S. Agency standards for rail transit, contributing to reduced greenhouse gases compared to diesel alternatives.

Ridership and impact

Usage statistics

The A Line reached its pre-COVID peak ridership in , averaging 23,800 weekday boardings. This marked significant growth from its early years, with cumulative boardings exceeding 4.5 million in the first 10 months of operation through January 2017. Annual ridership stood at 6.184 million in fiscal year 2023, reflecting a partial recovery from lows. By 2024, boardings totaled approximately 5.9 million, with monthly figures reaching 650,000 in August 2025—the second-highest in five years—indicating about 80% recovery to pre- levels as of late 2025. Ridership trends show steady pre-pandemic expansion driven by airport connectivity and urban commuting, followed by sharp declines of over 50% in 2020–2022 due to COVID-19 restrictions. Post-2022 rebound has been influenced by shifts toward hybrid work reducing peak-hour commutes, alongside resumed air travel; monthly averages from RTD financial reports post-2023 highlight this stabilization, with commuter rail like the A Line leading national recovery rates. Peak usage occurs during morning and evening rush hours for work commutes, supplemented by consistent airport-bound travel, which accounts for a substantial share of overall trips. are drawn from RTD's annual boardings reports and monthly financial statements.

Economic and environmental effects

The A Line contributes to the regional economy by reducing travel times and vehicle miles traveled, thereby generating substantial benefits estimated at a $6 return in local economic activity for every $1 invested in the program of which it is a part. This impact includes support for approximately construction-related jobs at the program's peak between 2011 and 2012, with ongoing employment opportunities in operations such as train conductors and maintenance roles. Near its stations, the line bolsters local job markets, particularly in areas like Aurora and Commerce City, where has spurred commercial and residential growth. By providing direct connectivity to , the A Line diverts single-occupancy vehicle trips from the heavily congested Peña Boulevard, aligning with regional goals to reduce drive-alone airport employee trips by 10% through options. This shift helps alleviate traffic pressure on the roadway, potentially yielding savings in fuel costs and accident-related expenses, as part of broader efforts to enhance safety and multimodal access to the airport. Environmentally, the A Line's electric-powered operations significantly lower compared to equivalent automobile , with public transit overall producing 84% less per passenger than single-occupancy vehicles. As part of RTD's sustainability initiatives, the line supports air quality improvements in the metro area by offering a low-emission alternative for commuters and regional , contributing to reduced regional transportation sector emissions. Future enhancements, such as expanded across RTD's network, are under study to further minimize the system's . In communities along its route, the A Line fosters economic development in Aurora, where it creates corridors for mixed-use projects and transit-oriented neighborhoods, and in Commerce City, where station-area promotes diverse and commercial hubs to attract . It also advances transportation equity by improving access for low-income residents through programs like RTD's LiVE, which provides discounted fares on the line and other services, enabling better connectivity to employment and essential destinations. Despite these gains, the A Line faces challenges including ongoing funding requirements for maintenance and potential expansions within the framework, compounded by ridership fluctuations observed in 2025 amid post-pandemic recovery and economic shifts.

References

  1. https://www.rtd-denver.com/open-records/reports-and-policies/facts-and-figures/a-line
  2. https://www.greaterdenvertransit.com/rtd-aline/
  3. https://www.rtd-denver.com/routes-services/rail
  4. https://www.rtd-denver.com/fastracks
  5. https://cdn.rtd-denver.com/image/upload/v1694642686/RTD%20Web/Doing%20Business/Construction%20Engineering/RTD-Commuter-Rail-Design-Criteria-Revised-040109_vduzxh.pdf
  6. https://www.rtd-denver.com/open-records/reports-and-policies/facts-and-figures/commuter-rail-vehicle
  7. https://www.greaterdenvertransit.com/rtdcomrailvehicles/
  8. https://www.politico.com/magazine/story/2016/05/what-works-denver-rail-system-growth-213905/
  9. https://www.denvergov.org/content/dam/denvergov/Portals/646/documents/planning/Plans/Denver_Union_Station_Master_Plan.pdf
  10. https://coloradonewsline.com/2021/02/08/rtd-betrayed-taxpayers-on-fastracks/
  11. https://rosap.ntl.bts.gov/view/dot/39729/dot_39729_DS1.pdf
  12. https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/150/Final_FTA_ROD.pdf
  13. https://archive.rtd-denver.com/sites/default/files/files/2019-04/2011_04_22_North_Metro_Record_of_Decision.pdf
  14. https://www.dailycamera.com/ci_13106230/
  15. https://www.denverpost.com/2009/07/04/money-woes-could-derail-fastracks-completion/
  16. https://www.railwaygazette.com/eagle-p3-takes-off/35221.article
  17. https://www.rtands.com/passenger/commuter-regional/rtd-begins-a-line-testing/
  18. https://www.railjournal.com/passenger/commuter-rail/denver-rtd-begins-a-line-testing/
  19. https://www.cbsnews.com/colorado/news/timeline-of-rtds-a-line/
  20. https://www.denverpost.com/2018/06/19/rtd-a-line-flaggers/
  21. https://www.bizjournals.com/denver/news/2019/02/08/rtd-a-line-quiet-zones.html
  22. https://www.westword.com/news/a-line-train-to-denver-international-airport-96-percent-reliable-10326846/
  23. https://www.transit.dot.gov/sites/fta.dot.gov/files/docs/funding/grant-programs/capital-investments/130316/co-denver-eagle-commuter-rail-profile.pdf
  24. https://cdn.rtd-denver.com/image/upload/v1745265269/A_l7mlek.pdf
  25. https://cdn.rtd-denver.com/image/upload/v1758826528/Finishing-FasTracks-Report_2025_Appendix_09-26-2025_A_xebiof.pdf
  26. https://www.rtd-denver.com/doing-business-with-rtd/construction-engineering/railroad-safety
  27. http://airnav.com/airport/kden
  28. https://frontporchne.com/a-line-first-new-positive-train-control-system-in-u-s/
  29. https://www.9news.com/article/news/local/next/answers-to-your-a-line-questions/73-c02d9882-65e3-481a-83ca-415a980f3b2e
  30. https://www.rtd-denver.com/trainhorns
  31. https://www.denverpost.com/2018/12/17/rtd-denver-commuter-rail-g-line-plan/
  32. https://frontporchne.com/rtd-says-line-crossing-problems-solved/
  33. https://cdn.rtd-denver.com/image/upload/v1739488151/2024_LRT_Design_Criteria_v43yhf.pdf
  34. https://www.rtd-denver.com/about-rtd/projects/quiet-zones
  35. https://www.denverpost.com/2019/04/04/rtd-quiet-zones-a-line-denver/
  36. https://www.up.com/news/service/tr030921-how-does-train-dispatching-work
  37. https://www.denverpost.com/2025/11/05/rtd-train-pedestrian-crash-aurora/
  38. https://denverite.com/2025/11/05/rtd-a-line-reopens-pedestrian-hit/
  39. https://www.rtd-denver.com/yoursafety
  40. https://www.rtd-denver.com/fastracks/a-line
  41. https://www.rtd-denver.com/how-to-ride/bus-rail-system/ticket-vending
  42. https://app.rtd-denver.com/facilities
  43. https://www.rtd-denver.com/how-to-ride/bus-rail-system/commuter-rail
  44. https://www.denverunionstation.com/transportation/
  45. https://www.denverunionstation.com/transportation/rail-and-bus/
  46. https://www.flydenver.com/parking-and-transportation/to-and-from/public-bus-or-train-rtd/
  47. https://app.rtd-denver.com/facilities/61st-pena-station
  48. https://www.rtd-denver.com/how-to-ride/parking
  49. https://www.flydenver.com/parking-and-transportation/
  50. https://schedule-pdfs.rtd-denver.com/api/file/current/A/Eastbound/4
  51. https://app.rtd-denver.com/route/A/schedule
  52. https://www.rtd-denver.com/fares-passes/fares
  53. https://www.rtd-denver.com/about-rtd/projects/commuter-rail-maintenance-facility
  54. https://denver.streetsblog.org/2019/04/23/with-g-line-opening-has-rtd-figured-out-positive-train-control/
  55. https://cdn.rtd-denver.com/image/upload/v1696451445/Quality-of-Life_Sustainability-Report_2020_0_mqeto4.pdf
  56. https://www.denverpost.com/2017/04/09/denver-airport-train-one-year-in/
  57. https://cdn.rtd-denver.com/image/upload/v1709053451/2023_Boardings_Ridership_Report_aenadp.pdf
  58. https://www.rtd-denver.com/community/news/rtd-leads-commuter-rail-ridership-recovery-nationally-from-pre-pandemic-levels
  59. https://www.rtd-denver.com/community/news/rtd-doubles-down-on-efforts-to-improve-service-and-enhance-the-customer-experience
  60. https://cdn.rtd-denver.com/image/upload/v1755274276/RTD_0625_Financial_Summary_zy8agi.pdf
  61. https://www.fhwa.dot.gov/livability/case_studies/guidebook/appendix/app06.cfm
  62. https://www.bizjournals.com/denver/news/2025/03/20/denver-airport-pe-a-boulevard-study-city-council.html
  63. https://www.flydenver.com/about-den/projects-and-infrastructure/pena-master-plan/
  64. https://www.rtd-denver.com/zero-fare
  65. https://www.rtd-denver.com/performance-dashboard/environmental-impact
  66. https://cdn.rtd-denver.com/image/upload/v1711123574/RTD_Climate_Action_Plan_jq8whk.pdf
  67. https://www.auroragov.org/business_services/planning/projects__plans___studies/transportation_planning/rail_information
  68. https://www.c3gov.com/Government/Urban-Renewal/72nd-and-Colorado-Station-Area
  69. https://www.rtd-denver.com/community/news/live-program-growth-expands-affordable-transit-access
  70. https://www.rtd-denver.com/about-rtd/financial-outlook
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