It’s hard to believe it has already been about 30 years since the “new” Denver International Airport (DEN) replaced Stapleton International. Since then, traffic has ballooned, stretching the limits of what the terminal can accommodate. As the team at DEN sought solutions for associated pedestrian circulation challenges, it honed in on alleviating a choke point in the center of the terminal. Fixing it required both finesse and brute strength, not to mention careful planning and clear communication.
Analysis showed that travelers boarding and deboarding the passenger trains in Concourse A were getting snarled up at the escalator banks. There was an existing set of eight escalators, four on the north side and four on the south side in a split configuration—on each side, there was one escalator leading up to a landing and on to the next floor, with the same setup going down.
“The previous situation created a bottleneck, and we saw backups when multiple flights hit the concourse at the same time,” explains Matthew Robb, DEN’s senior vice president of technical operations. “That was a pain point for us.”
 facts&figures
Project: Adding New Escalators to Improve Passenger Flow Location: Denver Int’l Airport Scope: Removing 8 existing escalators; installing Construction Cost: $8.96 million Funding: Airport Timeline: Contract awarded Oct. 2021; work completed General Contractor: PCL Construction Services Escalator Removal & Installation: Industrial Constructors/Managers (ICM) Structural Engineering Consultant: Baur Engineering Escalator Manufacturer: Kone Escalators Installed: 16 Weight: About 20,000 lbs. each Maintenance Contractor: ThyssenKrupp Key Benefits: Improving access to in-terminal train; newer, faster escalators move passengers more efficiently |
In 2023, DEN welcomed a record-breaking 77.8 million passengers, which was 12.3% more than in the previous year. Compare that to the 31 million passengers the airport served in 1995 when it opened, and it’s no wonder the escalator banks could feel cramped during busy times. But the escalators weren’t the only equipment targeted for replacement. This was part of a much bigger initiative.
“We’re in the process of systematically replacing 358 conveyances—including power walkways, escalators and elevators,” Robb says. “A lot of those were original to the airport, which means they are now approaching 30 years old and are more difficult to maintain.”
Bracing for the trials ahead, DEN worked closely with familiar partners to devise a plan to solve the logjam.
A Heavyweight Challenge
The airport’s general contractor, PCL Construction Services, brought in Colorado-based Industrial Constructors/Managers (ICM) to help remove the existing eight escalators and replace them with 16 brand-new units manufactured by Kone. ICM combined its expertise in rigging applications with structural engineering support from Baur Engineering. Together, the firms calculated the beam size needed for the new escalators, which each weigh about 20,000 pounds.
Crews extracted the eight existing escalators and hoisted them with cranes through the concourse windows. In general, they worked between 9 p.m. and 5 a.m. because aircraft were operating just outside the windows during the day. Foot traffic was diverted to the opposite side of the terminal from where the work was being completed.
During the planning phase, engineers discovered that the project plans required adjustments to beef up the support structure because the new escalators were so heavy.
“The reason it took us almost an entire year is because we discovered some structural challenges, which caused some complications,” Robb says. “We had to bolster the superstructure to accommodate the weight.”
Crews used a hydraulic gantry system to help lower the new escalators into place. The bridge-like structure that supported the crane from overhead consisted of pistons on a wheeled base that was fixed to a track system and two engineered rigging beams spanning the open space. The pistons were all individually managed by remote-controlled pendants, and crews from ICM received specialized training to ensure the required control.
Delicate Maneuvers
Like the children’s game Operation, which requires a steady hand to extract and re-insert plastic organ pieces into a cartoon patient, DEN’s escalator project required precision and near-perfect execution.
Demolition and steel installation commenced on the north side of Concourse A in February 2022, and crews began installing the new escalators there in August 2022. Preparatory work for the new south escalators commenced January 2023 and was completed in
June 2023.
After the old escalators were removed, PCL cut a large hole into the terminal and buttressed it with structural steel and concrete to underpin the floor. Framing the opening was a steel-reinforced glass railing for visibility and safety. The new escalator units, hoisted by a crane from the outside, were guided carefully through the window. It was a tight space, as the escalators were nearly the same width and height as the window opening.
Once inside, the new escalators were moved to the concourse level and guided into place with the hydraulic gantry system. Kone, PCL and ICM worked together to coordinate the rigging process, which included restricting access to the gate areas and concourse, and clearing walkways before anything moved an inch. In tandem, PCL relocated the temporary construction walls to cordon off the next phase.
Sometimes, the team had to delay work due to changing airline schedules because an aircraft would be near the window where crews needed access.
“Working in an operating facility where there were still pedestrians coming in and out, we had to make sure nothing would compromise safety,” stresses ICM Project Manager Pat Williams. “We did the majority of the work at night, including all of the rigging, while we did some steel work during the day.”
Creating fluidity in the process was key, he adds, because changing conditions and schedules were never going to be 100% predictable.
Safety and Access
With care for the airport and its workers and visitors in mind, ICM submitted a safety plan for each phase of work. Various portions included complex engineering, extremely heavy escalators and working from significant heights. Williams notes that a safety plan for the hydraulic gantry system was particularly important because it had to be aligned and weighted perfectly.
“We also had to be careful to not damage the terrazzo,” Robb adds. “We put down plywood over the flooring, and there was an overhead crane installed at the side.”
Daily safety checks with job safety analysis included inspecting equipment and weld points, as well as identifying potential work hazards that could result in lost work time. ICM coordinated closely with Glazers, the firm that provided the glass railing, to ensure the steel reinforcement was aligned appropriately and safely.
The phased approach presented a challenge as it related to concourse traffic because it required limiting access one piece at a time.
“When we started this project, we had to reduce the number of up and down escalators, first shutting down the north side and then the south side,” Robb says. “That really put a focus on maintaining the uptime of the existing escalators.”
ThyssenKrupp bolstered its preventative maintenance for the existing units to keep them operational and shifted upkeep to overnight hours to minimize impacts to ongoing operations. After the north side installations were complete, the airport’s capacity was back to the level it was before the escalator project began, allowing the team a bit of breathing room as it worked on the south side.
Ultimately, the team removed eight existing escalators and installed 16 new units on schedule and on budget. With careful attention to workplace safety, there were no reportable incidents throughout the various phases.
“I think the key takeaway is [the importance of] coordination with the general contractor and the owners, and planning everything ahead of time cohesively to make it a successful project,” Williams reflects. “Oftentimes, projects are designed to get things going quickly, and some organizations don’t engage their tradespeople early enough to understand what it will take to complete a project. We’ve done this kind of thing over and over, which means we can look at the site conditions and understand how to overcome different obstacles. Overall, this was a smooth project with excellent communication.”
With DEN now ranked as one of the top 10 busiest airports in the world, it’s more important than ever for management to have a clear path forward about how to handle passenger traffic. Its current strategic plan includes two consecutive phases. Vision 100 focuses on readying the terminal to handle 100 million annual passengers within the next eight to 10 years. Operation 2045, named for the airport’s 50th anniversary in the year 2045, is designed to accommodate a projected volume of 120 million annual passengers.
The recent escalator project in Concourse A is easing flow to and from the passenger trains and helping DEN prepare for the next decade or more.
