Denver International Airport Considers Public Transit Expansion to Alleviate Traffic Congestion
Denver International Airport officials are exploring new strategies to address the growing traffic congestion along Peña Boulevard. In addition to road widening, they are now looking into enhancing public transit options as a viable solution.
This shift in approach could mean improved train and bus services for travelers heading to and from DIA in the future. The decision to consider expanding public transit came as a mandatory federal review process commenced for the Peña Boulevard project, which aims to address the issues on the two-lane freeway connecting Denver with the airport and the rapidly developing northeastern suburbs. However, securing funding for the project, which is estimated to cost hundreds of millions of dollars, remains a challenge.
Several advocacy groups, including Green Latinos, Greater Denver Transit, and the Southwest Energy Efficiency Project, have been vocal in opposing highway expansion projects in the Denver metro area, citing concerns about increased air pollution. They argue that widening roads only offers a temporary fix and ultimately leads to more traffic congestion in the long run.
“Are we going to continue expanding roads for vehicles without considering the impact on air quality?” questioned Ean Tafoya, director of Green Latinos.
The airport planners are now looking at boosting the frequency of the Regional Transportation District A Line trains by adding tracks, a proposal that was initially excluded from the Peña Master Plan. Additionally, the construction of bus-only lanes to improve bus access is being evaluated as a core alternative to alleviate traffic congestion, according to a report in the Denver Post.
“Rail expansion and other transit alternatives are being considered as part of the evaluation process,” stated DIA project manager Danielle Yearsley in response to inquiries. “A comprehensive range of alternatives is being assessed through the National Environmental Policy Act review, including options that were previously ruled out by the Peña Master Plan.”
The NEPA planning process mandates a thorough evaluation of the environmental impact of various alternatives to be eligible for federal funding. The final decision by DIA will require approval from the Federal Aviation Administration.
The worsening traffic congestion on Peña Boulevard has become a major concern for both air travelers and local residents. The road, spanning 11 miles from Interstate 70 to DIA’s main terminal, now experiences significant delays, with the average drive time increasing from eight minutes to 24 minutes. Unpredictable traffic jams and accidents further exacerbate the situation, causing delays of over half an hour at times.
During peak travel periods, the RTD operates trains along the A Line at the highest possible frequency, with services running every 15 minutes. However, the frequency decreases to around every half an hour during evenings and early mornings, while buses to and from DIA often run only once an hour.
The A Line commuter trains, which can accommodate over 300 passengers, have seen a decline in average daily ridership from 24,000 in 2019 to approximately 20,600. Despite the potential capacity to transport 60,000 passengers daily, the trains carried 650,000 riders in August 2025, down from 744,000 in August 2019. In contrast, Peña Boulevard handles an average of 187,000 vehicles per day.
Denver councilman Kevin Flynn expressed skepticism about rail expansion as a feasible solution, highlighting the underutilization of the A Line and accessibility concerns for some metro residents.
“Transit enhancements catering to the entire metro area should be a key consideration in the Peña Boulevard study, and introducing express bus services from areas not served by the A Line could effectively utilize expanded managed lanes,” Flynn suggested. “Expanding the A Line may not be financially viable given the current underutilization of the trains.”
When Denver initially constructed the airport and Peña Boulevard in the early 1990s, the FAA provided grant funding to support land acquisition in 1989 and 1996. By accepting these funds, Denver agreed to adhere to FAA regulations regarding the permissible uses of airport revenue.
Over the decades, Denver and Aurora encouraged residential, commercial, and industrial development in the vicinity, leading to increased traffic on Peña Boulevard and complicating access to the airport.
Denver Mayor Michael Johnston’s administration reaffirmed its commitment to fostering development around Denver International Airport, with a focus on exploring public transit improvements. Given the airport’s significant economic impact on the region, Mayor Johnston’s office emphasized the importance of ensuring that any changes to Peña Boulevard align with both present and future needs.
FAA officials have clarified that while they will not finance any part of the Peña Boulevard project, the airport can utilize its revenue to fund a portion of the expansion.
However, the specific allocation of funds for the project is yet to be determined.
Advocates from Greater Denver Transit, Green Latinos, the Sierra Club, Denver Bicycle Lobby, and SWEEP have proposed the establishment of a large parking lot near RTD’s 40th & Airport station, close to the I-70 interchange where Peña Boulevard begins. This setup would enable airport travelers to park their vehicles and take the A Line for the final leg of their journey to DIA.
Public transit supporters have also urged RTD to introduce new bus routes along the E-470 beltway connecting Highlands Ranch and Parker with DIA, similar to the Flatiron Flyer service linking DIA with Boulder.
“Nationwide evidence indicates that expanding roads does not offer a sustainable solution to traffic congestion,” noted James Flattum, co-founder of Greater Denver Transit. “By increasing the frequency of the A Line, we can eliminate the inefficiency of waiting for shuttles in parking lots and provide a more competitive transit option for airport travelers compared to driving.”
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