Denver International Airport is moving toward a major passenger-movement change that could matter far beyond Colorado: new underground pedestrian walkways connecting its concourses, giving travelers a backup to the train system that currently carries passengers to most gates.
The plan, announced May 26 by Denver Mayor Mike Johnston and DEN Chief Executive Officer Phil Washington, would repurpose portions of the airport’s existing underground baggage tunnels to create walkable links between Concourse A and Concourse B, and between Concourse B and Concourse C. Construction is expected to begin in 2027, around the time DEN’s main terminal renovation is expected to finish.
For U.S. travelers, the key point is not that every passenger will suddenly choose to walk across one of the country’s largest airports. It is that DEN, a major hub for United Airlines, Southwest Airlines and Frontier Airlines, would finally have a second airside option when its automated train is crowded, delayed or temporarily out of service.
Why DEN’s train dependency matters
Denver’s layout makes the airport unusually dependent on its underground train. Passengers can already walk from Jeppesen Terminal to Concourse A by bridge, but travelers heading to Concourses B and C generally rely on the train. That makes the train not simply a convenience, but a core part of the airport’s ability to move passengers to and from flights.
Local reports cited airport officials as saying the train serves more than 150,000 riders per day. Washington said the train has strong overall uptime, but acknowledged that when it is not working, the result can be severe crowding and operational stress. Recent train disruptions, including a power-related incident earlier this year, have kept the issue highly visible for travelers and airlines.
The proposed walkways are designed to add redundancy. In airport terms, that word matters: redundancy means passengers and staff have another path through the system when a single piece of infrastructure becomes a bottleneck. At a hub airport, even short interruptions can ripple into missed connections, longer boarding delays, fuller rebooking lines and tighter turnarounds for aircraft.
A hub that is still growing
DEN is not planning this project in a shrinking market. The airport reported a record 82.4 million passengers in 2025, making it the fourth-busiest airport in the United States and the 10th-busiest in the world. DEN’s long-term Vision 100 plan is built around preparing the airport to serve 100 million annual passengers.
That growth has already reshaped the airport. DEN has added 39 gates across its concourses in recent years and is continuing work on the Great Hall renovation in the main terminal. Airlines have also leaned heavily into Denver because of its central geography and strong domestic connecting role. For many travelers, DEN is not the final destination; it is the place where a short connection determines whether they reach the West Coast, Mountain West, Midwest or international gateway flight on time.
That is why the walkway plan is more significant than a standard airport amenity. At a smaller airport, a new pedestrian route might mainly improve comfort. At DEN, it could become part of the reliability toolkit for one of the country’s most important domestic connecting hubs.
What the project would and would not solve
The pedestrian tunnels would not replace the train. Most travelers, especially those with tight connections, mobility limitations, children, heavy bags or long gate distances, will still depend on the automated system. The train will remain central to DEN’s operation, and the airport is separately investing in new train cars and other modernization work.
The walkways would instead create an alternative for passengers who are able and willing to walk when the train is backed up. That could help during peak travel periods, service interruptions, special events or weather days when passenger flows surge and small delays compound quickly.
The project also will not help this summer’s travelers. With construction expected to begin in 2027, passengers flying through Denver in 2026 should still plan around the current train-dependent layout. Travelers with short connections should review terminal maps, keep an eye on airport alerts and avoid assuming that a Denver connection will be simple just because the flights are domestic.
What travelers should do now
For passengers booking through Denver, the practical advice remains straightforward: build more cushion into connections when possible, especially on itineraries that involve separate tickets, late-night arrivals, winter weather, peak holiday periods or flights where the next departure is not until the following day.
Travelers can also reduce stress by checking gate information early and monitoring live flight status before heading to the airport. Odyssey travelers using Denver can review the Denver Airport guide for airport basics and the DEN live flight board for current arrivals and departures. Those ending a trip in Colorado may also want to compare DEN airport transfers and taxis or Denver airport car rental before arrival, since ground-transport decisions can add another time constraint after a long connection.
For travel advisors and corporate travel managers, the DEN announcement is a reminder to treat airport infrastructure as part of itinerary quality. The cheapest fare is not always the best option if it relies on a narrow connection at a hub under construction or operating near peak capacity.
A bigger lesson for U.S. airports
Denver’s walkway plan reflects a broader challenge across U.S. air travel. Passenger volumes have recovered strongly, airlines are concentrating traffic through major hubs, and airports are trying to modernize while staying open at full speed. That combination makes redundancy, passenger flow and terminal design more important than ever.
If the DEN project is delivered as planned, it could give travelers something simple but valuable: a choice. When the train works smoothly, most passengers will keep riding it. When it does not, a walkable airside route could be the difference between waiting helplessly in a crowd and moving toward the next gate.
For one of America’s busiest airports, that backup option may become a meaningful part of the passenger experience as Denver continues its push toward 100 million annual travelers.