Denver International Airport is turning a long-dormant underground tunnel into a continuous pedestrian walkway that will link every concourse, airport officials say. The idea is to give travelers a quicker, cheaper backup when the people-mover trains go down, and connections start looking dicey.
According to The Denver Post, design work is scheduled to start in 2026, with construction planned for 2027 and the walkways opening in 2028. The paths are expected to be about 17 feet wide, and airport leaders estimate the tunnel conversion will run between $300 million and $700 million. The money would come from airlines and airport revenues, not local taxes. The Post also notes that building new concourse bridges would be far more expensive, with officials putting that option at $2 billion to $3 billion, which is a big reason the tunnel plan is getting the nod.
New Train Cars and a Modernization Push
DEN is already in the middle of a major refresh of its automated people-mover system as part of a broader reliability effort. In a press release, DEN said an initial order of 26 Innovia APM R cars cost about $78.85 million, and that new lightweight aluminum vehicles have been phased in to boost capacity and cut wait times. The modernization effort also includes upgrades to signaling, power distribution, and maintenance facilities.
Costs, Breakdowns and Why Now
The tunnel proposal follows a run of short train outages that highlighted the lack of any second route between the terminal and the concourses. Airport records reviewed by The Denver Post show the people-mover broke down 262 times over the past two years, with each stoppage averaging around four minutes. Airport spokespeople also pointed out that the system still operated about 99.9% of the time over the last 12 months. The Post reports that the broader modernization work, including signal and control upgrades, is part of roughly $148 million in projects meant to expand capacity and reduce waits. Officials told the paper that putting the idle tunnel back to work is the fastest and most affordable fix on the table. “Travelers won’t notice the construction underground,” Mayor Mike Johnston told the Post.
What Travelers Should Expect
Airport leaders say most of the heavy lifting will happen below the terminal, so ticketing counters and curbside areas should see minimal disruption. Previous train stoppages have pushed the airport to “explore other ideas” and weigh the costs and benefits of a backup system, as Denver7 reported, so travelers can expect more outreach and planning updates once the design work ramps up.
Officials say design work begins this year, and the airport will roll out more detailed plans as the project moves into engineering and permitting. The tunnel conversion is meant to give flyers a dependable fallback when the people-mover is out of service and to cut down on high-stress connection times between concourses.
