Denver International Airport (DIA) experienced a brief disruption on Wednesday after smoke from an ongoing construction project triggered an alarm, prompting officials to temporarily halt underground train service between the terminal and concourses. The pause began just before noon, causing delays and forcing travelers to find alternate routes through the busy airport.
Airport officials initially announced the stoppage on social media, explaining that a smoke alarm had gone off and safety protocols required shutting down the underground train. A little more than two hours later, the airport clarified the source of the problem: smoke from construction activity inside Jeppesen Terminal.
According to the update, the smoke originated on Level 5 of the terminal, where crews are continuing work on the multi-year Great Hall renovation. The airport said, “We thank our passengers for their patience,” as operations gradually resumed.
During the pause, DIA directed passengers to use the A-bridge, a pedestrian walkway connecting the terminal to Concourse A. While the bridge allows foot traffic to continue, it adds significant travel time for passengers with connecting flights or those carrying heavy luggage.
The smoke was linked to the Great Hall Project, DIA’s large-scale effort to modernize and redesign the Jeppesen Terminal. The multi-phase project includes upgraded security checkpoints, expanded ticketing areas, new retail and dining options, and infrastructure improvements throughout the terminal. Construction activity remains ongoing across several zones, which can involve welding, cutting, and other work that may produce smoke or sparks.
Incidents like Wednesday's, where alarms are triggered by construction activity, are not uncommon in major airport renovations, but they can create ripple effects across tight schedules and high traveler volumes. DIA is one of the busiest airports in the nation, and even a brief train pause can cause lines to swell and movement through the terminal to slow dramatically.
Passengers arriving during the midday disruption reported longer walks, packed escalators, and confusion as they navigated alternate pathways. Although the delay lasted only a few hours, it created challenges for travelers trying to catch flights, retrieve bags, or move between concourses.
Airport officials emphasized that safety systems worked as intended, and the pause was a precautionary step to verify that there was no threat beyond the construction-related smoke.
The airport returned to full operations shortly after the source was confirmed and ventilation cleared the affected area.
The Great Hall Project continues to reshape DIA’s main terminal and is projected to enhance passenger flow, increase security efficiency, and modernize the overall travel experience. However, with construction expected to continue into future phases, intermittent disruptions may still occur.
For now, the incident serves as a reminder of the challenges that come with rebuilding a major international airport while keeping daily operations moving.
Originally reported by Jesse Sarles in CBS News.
