The opening of nearly three dozen new gates at Denver International Airport this year has its two largest carriers plotting rapid expansions that will test the busy airport’s ability to process millions more passengers and get them to their flights.
DIA has billions of dollars worth of projects underway to accommodate that growth on some fronts. Larger, long-overdue security checkpoints will begin opening by early 2024 as part of its drawn-out $2.1 billion terminal renovation.
But other pinch points could get worse if the airlines stick to their plans — especially on the underground concourse train system and on DIA’s runways, The Denver Post found in a review of airport-commissioned passenger and air traffic forecasts, planning documents and statements by major airlines.
The aggressive growth plans include a nearly 20% increase in daily departures by Southwest Airlines by this fall, and likely much more in coming years. By 2025, United Airlines aims to increase its schedule out of Denver by more than 50%, ramping up to nearly 700 departures on an average day.
While the airport has set plans in motion to increase the train’s capacity, the timing is potentially tight. It’s based on growth projections that are more conservative than those shared with DIA’s planning consultant by the airlines.
DIA leaders express confidence that they’ll keep up with the growth, no matter how fast it comes, as part of initiatives they’re working out under the airport’s “Vision 100” strategic plan. That plan is aimed at accommodating 100 million passengers a year within the next decade — or even sooner, as looks likely based on growing travel to and from Denver as well as expanding connections through DIA.
But they acknowledge that may mean trains linking the terminal with DIA’s three concourses will get more crowded at peak times than they’d prefer, potentially beyond the 50-person capacity per car that they base their calculations on.
A small capacity boost is coming next year when batches of brand new train cars are set to arrive, more than two years behind schedule, enabling the running of an extra train at peak times. But more significant train capacity, including platform modifications to allow the running of longer trains, won’t come until the end of the decade.
“One of the things I would say is we still have a lot of work to do,” CEO Phil Washington said in an interview. “We were disappointed with the delay as far as the supply chains on the train cars that are coming in.”
He added, “I hate to see the trains crowded.”
As for DIA’s plan to build a seventh runway, which is now in the environmental review phase and hasn’t received a formal green light from federal officials, officials hope to eke out more breathing room that would avert planes backing up on taxiways. Projections for aircraft movements now indicate the six-runway airfield will reach capacity by 2027 — a year before the project schedule calls for the new runway’s completion.
But Bill Poole, DIA’s senior vice president of planning and design, said a planned new taxiway would make airplane movements more efficient, boosting the current configuration’s capacity enough to last up to five more years.
“We think we’re right in the sweet spot in terms of timing for the seventh runway,” Washington said.
Still, a separate forecast built by InterVISTAS Consulting for DIA, based on the airlines’ pre-pandemic plans shows the airfield could reach even that higher capacity even before 2027. The Post obtained InterVISTAS’ planning reports and presentations from recent years via a public records request; DIA’s legal office redacted significant portions of one planning document that were based on confidential information provided by the airlines.
Though the forecasts come with higher uncertainty because of the severe pandemic effects on air travel in the last two years, DIA’s traffic this year is expected to recover nearly to its pre-pandemic trajectory — almost as if the pandemic didn’t happen, and a remarkably fast turnaround from two years ago.
DIA is projecting 73 million passengers this year, which would be almost 6% more than 2019’s record-setting 69 million. The airlines’ projections are closer to 75 million, Washington says, though he sees that higher figure as unlikely to be hit after air traffic dipped temporarily at the start of the year during a COVID-19 surge fueled by the omicron variant.
Train is linchpin that keeps DIA running
The train is DIA’s most vital connection — one that requires constant upkeep to keep it running.
The Automated Guideway Transit System, operated remotely from an underground control center, has been DIA’s key people-mover since it opened in 1995, providing the only link between the terminal and concourses B and C. Passengers can reach Concourse A using either the train or a bridge from the terminal.
The AGTS hums reliably nearly every day, but in rare instances it’s failed, including a partial shutdown last August that wreaked havoc for hours, backing up passenger flows, after a wheel assembly broke and caused track damage. That incident highlighted its recurring vulnerability, since DIA lacks a full backup system or walkways between all concourses.
But the system’s 31 train cars, which operate in four-car configurations of up to seven trains, are getting old. The air conditioning frequently breaks down.
During a recent tour of the underground maintenance facility, Shawn Bingham, the operations manager with Alstom, which operates the AGTS, underlined the need for recurring maintenance and inspections to keep the trains running as several have exceeded 1.5 million miles of service.
There’s a push-pull to the operation: They only run all seven trains when it’s necessary; otherwise, they wouldn’t have enough time to perform sufficient maintenance to keep them running. Given the significant variation in passenger demand during the day, which is driven by airlines’ clusters of arriving and departing flights, DIA’s system administrator, Seth Craft, and Bingham’s team opt to run as few as four or five trains during some daytime hours.
A recently installed counter system on the trains has enabled them to drill down further, resulting in the running of five trains at some times they used to run six.
But this spring, the higher crushes returned as spring travel exploded, especially during the early evening hours, Craft said. So they’ve needed all seven trains again at times.
“The schedule is drilled down to the hour,” Bingham said. “We will see some changes (to demand) — on-the-fly changes, due to weather, snow events, late flights, delays from other airports. So we can make the adjustment on the fly to increase the number of trains on the system to accommodate that.”
The long-delayed new vehicles arriving next year will replace about half the aging fleet and add 10 extras, all of them newer models that can’t connect with the remaining older ones. That will allow DIA and Alstom to run eight trains at peak times while keeping more vehicles as backup.
But eight trains is the maximum that will fit on the system. The trains advance to the next station on the loop in unison.
The availability of an eighth train will expand capacity by 13% at the busiest times, to about 7,500 riders per hour in each direction, DIA spokeswoman Stacey Stegman said.
Trains likely to get more crowded during decade
Under DIA’s passenger traffic projections, Washington said, that will be enough to keep up with near-term growth in traffic among passengers for several years. He said it won’t be until traffic exceeds 90 million passengers a year — projected close to 2030 — that the system will need longer trains of at least five cars, accommodating 10,000 riders per hour in each direction.
By then, DIA would need to modify all of the platforms to install more doors, increasing from four to six, and finish replacing its older train cars with newer models.
But even before that point, the train cars are likely to get crowded more frequently.
That much is clear from breakdowns of InterVISTAS’ projections at the busiest hours in a presentation prepared early last year and obtained through a public records request. The consultant zeroed in on the peak passenger flows of people starting or ending their trips at DIA during its busiest hours. That origin and destination traffic is a good proxy for passengers using the train, though some travelers with connections on other concourses must use it, too.
DIA’s recently released $3.1 billion capital plan for the next five years doesn’t yet include the platform modifications, but it does budget a train order with Alstom to replace the 15 remaining older cars. That order hasn’t yet been proposed to the City Council.
The capital plan also includes a feasibility study of alternative ways to move passengers, building on DIA’s recent solicitation of private-sector ideas for underground walkways and other ideas — all likely to be costly and take years to happen. DIA has said it received 18 responses, which haven’t been publicly released.
In seeking those ideas, airport leaders noted that an alternative system, if built, would not only serve as a backup to the train system but also could relieve pressure at busy times.
Another factor is sure to put more pressure on the train system: United, DIA’s largest carrier, has leased nearly two dozen of the new gates added across Concourse B, which it has dominated since DIA opened, as well as on Concourse A, where it’s been expanding its footprint. The increasing use of Concourse A means more connecting passengers must take the train between A and B, jocking at busy times to cram onto nearly full trains.
Steve Jaquith, DIA’s chief operating officer — and a former United executive in Denver — said he was comfortable with DIA’s plans to expand the train’s capacity.
“The capacity capability of those cars is greater than 50, so we’re comfortable that we have enough capacity,” he said. “I think the thing we’re going to really be focused on is that we have the correct service levels.”
Traffic surge at DIA has outpaced other airports
Though DIA saw its growth stall during the pandemic, its recovery has outpaced that of many larger airports. Last year it ranked as the world’s third-busiest airport in terms of passenger traffic, a much higher ranking than its No. 16 placement in pre-pandemic times.
While the runway is still in early planning stages and the train is getting crowded, airport officials’ attention largely has been fixed elsewhere — chiefly on the Great Hall Project in the terminal.
The undertaking hit major turbulence in 2019, when DIA terminated the original contractors over cost and delay disputes. More recently, the rebooted project won city leaders’ blessing for major additions to the scope that have extended the timeline through 2027 or 2028.
“It is a great concern,” Denver City Councilman Kevin Flynn said of the Great Hall project’s dominance of the discussion for so long. “It has put a lot of pressure on the team, obviously, to have the Great Hall go through the disruption that it went through. It’s a lot more staff resources. But we do have a lot of staff to pursue other projects.”
Washington, who took over last summer for retiring leader Kim Day, fought to finish the Great Hall project with many of its original components, along with some new ones, by arguing it would keep up with the airport’s growth.
But he’s acknowledged to council members the other challenges posed by DIA’s return to robust growth, including the increasing strain on the train system.
“What they’re trying to do is anticipate what the airlines are going to do,” said Mike Boyd, an Evergreen-based aviation consultant, about DIA managers’ position.
And that, he said, can be a tricky business, since “you’ve got to plan 10 years in advance for everything.” For now, the airlines are going gangbusters on Denver, which became the largest operational base for both United and Southwest during the pandemic.
By the end of the decade, Washington said, another gate addition could be in the cards if the demand is there. But the next time DIA goes big, likely in the 2030s, it will be time to decide on where to place a new concourse building — and potentially a second terminal, as the existing one maxes out.
Planning studies have indicated that a Concourse D, built past Concourse C, would require at least another train loop to be built, a highly costly prospect. The cheaper option at that point, according to concepts floated in speculative discussions, would be the building of gate wings off the current terminal.
In the shorter term, the airlines have faced turmoil nationally from staffing shortages, resulting in some trimming of flight schedules.
Staffing shortages are among the reasons Washington said he wouldn’t want to base capital expansion decisions solely on the airlines’ long-term plans.
“It’s one of the threats to these forecasts that even the airlines have out there,” Washington said. “So when people say … ‘You guys are being too damn conservative,’ well I don’t think so. I actually think we’re right on.”