Denver airport to add underground passenger walkways between concourses – Image for illustrative purposes only (Image credits: Unsplash)
Denver International Airport is preparing to turn sections of its long-idle underground baggage tunnels into pedestrian walkways that will link the main terminal with Concourse A and provide backup routes between concourses. The move addresses recurring disruptions on the airport’s aging train system while drawing on infrastructure built for a baggage-handling project that never worked as planned. Construction could begin as early as 2027 once final designs are complete.
Persistent Train Disruptions Drive the Need for Alternatives
The airport’s Automated Guideway Transit System has long been the sole connection between concourses A, B and C, and it remains the only option for passengers moving between those facilities. Mechanical issues, though infrequent, have forced the use of shuttle buses on multiple occasions, including a notable outage in May 2026. Even brief stoppages create platform crowding and missed connections because of the high volume of travelers passing through the facility each day. Officials note that the trains operate without incident more than 99 percent of the time, yet the consequences of any downtime are magnified by the airport’s growth. A $75 million modernization program is already underway, adding new cars and replacing aging components as part of a broader plan to handle up to 100 million passengers annually. Still, planners concluded that a parallel pedestrian option would improve reliability.
Repurposing Infrastructure From a Failed 1990s Project
The tunnels in question were constructed for an automated baggage system whose repeated failures delayed the airport’s original 1993 opening by 16 months. Large portions of the network have sat largely unused for decades, leaving behind concrete corridors that are wide enough for two-way foot traffic. Removing leftover equipment and installing proper flooring, walls, ventilation and lighting will be required before passengers can use them. Vertical circulation – moving travelers from concourse level down to the tunnels and back up again – remains one of the more complex engineering tasks. Bridges between concourses were considered but rejected on cost and schedule grounds, while more unconventional ideas such as ziplines were dismissed as impractical. The tunnel approach emerged as the most feasible during planning sessions involving airport staff and airline representatives.
Estimated Cost and Construction Timeline
Early projections place the total cost between $300 million and $700 million, a wide range that reflects the current conceptual stage of the work. Once detailed engineering is finished, crews could start construction in 2027. The project forms part of the airport’s “Vision 100” strategy and has received support from Denver’s largest carriers. United Airlines, American Airlines and Southwest Airlines have all endorsed the plan. United’s vice president of airport operations, Jonna McGrath, described the walkways as a significant investment that will give customers more options during connections. Southwest’s vice president of customer experience and innovation, Lisa Hingson, called the addition a tremendous enhancement to recent operational improvements. American’s vice president of corporate real estate, Amanda Zhang, noted that the walkways will increase flexibility and operational resilience.
Local Leadership and Lingering Airport Lore
Denver Mayor Mike Johnston welcomed the announcement as a clear benefit for travelers. He also acknowledged the airport’s long-standing reputation for underground mysteries, suggesting that passengers using the new walkways might finally get a closer look at the tunnels and decide for themselves what is fact and what is fiction. The airport has previously leaned into those stories with public exhibits rather than outright denial. The pedestrian routes will not replace the train system but will serve as a practical backup and an alternative for shorter segments, such as the walk from the terminal to Concourse A. By transforming decades-old infrastructure into everyday use, the airport is addressing a long-standing pain point for connecting passengers while giving new purpose to space that has remained largely empty since the 1990s.
