DENVER — The record crowds expected at Denver International Airport this holiday season will be required to navigate a partially gutted central terminal that disorients even the most seasoned volunteer airport ambassadors.

Temporary white aluminum walls crisscrossing the Jeppesen Terminal’s fifth floor already stymie travelers hunting for security, baggage claim, bathrooms or an Uber. Exposed steel beams, wires and concrete loom above a terrazzo floor where passengers like Liz Larsen step after ascending an escalator from a train connecting the terminal to concourses.

“This is the worst airport to go to,” said Larsen, a liability bodily injury specialist for Nationwide who arrived recently on a flight from Houston to attend training in a Denver suburb. “I feel like I need a divining rod to get through it.”

Passenger inconvenience reached a tipping point in August when the city and county of Denver terminated a $770 million contract with Great Hall Partners following disagreements over budget, schedules and safety. The demise of the public-private partnership is instructive for other airports as they consider overhauls, analysts said.

As construction in Denver ground to a halt, airport officials issued a plea for volunteers to join the facility’s 300-strong ambassador program. They hope to bring 15 more black-hat-and-checked-vest-wearing envoys on board by Thanksgiving.

With one of the busiest times of the year days away, uncertainty around the stalled project’s timeline puts pressure on the nation’s fifth-busiest airport to retain its reputation for top-notch customer service. Posting record-breaking traffic for 47 out of 48 months, the country’s largest airport by land is bursting at the seams.

“Our airport was built for a maximum of 50 million passengers a year — we think we are going to hit 70 million in 2019,” said Kim Day, the airport’s chief executive. “We may be the nation’s newest airport, but we are almost 25 years old and we are holding elevators and escalators together with bubble gum and duct tape.”

To address this, a huge, $3.5 billion capital improvement program is underway, including the Jeppesen modernization, 39 new gates, and amenities such as outdoor patios and fire pits, along with roadway and airfield improvements.

The multiphase terminal project, which began a year ago, will relocate security screening, consolidate ticket counters, and add concessions as well as new bathrooms and conveyances. The first phase, which includes reworking ticket counters in the center area, was supposed to be finished in May.

Security screening consumes much of the open fifth floor under Jeppesen’s iconic tented roof designed to mimic the snowcapped Rocky Mountains that loom to the west. The snaking lines, screening equipment and conveyor belts were shoehorned into the exposed area after 9/11, Day said, and leave travelers vulnerable to an attack by an active shooter.

Aging airports

Record crowds are taxing outdated infrastructure at scores of airports nationwide. Major hubs including Atlanta, Chicago, Dallas, Los Angeles, Newark, New York (John F. Kennedy and LaGuardia), Salt Lake City, San Diego and others are investing billions in new and modernized terminals.

These projects are designed in part to provide restaurants and shops unique to each region that appeal to a growing number of Americans with above-average incomes who are traveling more as they age. They also try passengers’ patience as they attempt to navigate construction sites in facilities that operate 24/7.

“If airports hope to continue to attract passengers, they need to be improving the quality of the experience,” said Mario Angastiniotis, a director in Fitch Ratings’ global infrastructure group. “This means they will disrupt the passenger flow in the short term, but in the long-term airports are in a position to benefit.”

Perhaps nowhere in the country is this phenomenon more on display than at Denver International — airport code DEN — which at 53 square miles is more than twice the size of Manhattan, with room to grow. Once derided as an economic boondoggle, the facility is now so maxed out that airlines are fiercely competing to lease 39 new gates before the scheduled completion, in 2021, of a $1.5 billion project to expand the airport’s three concourses.

Superlatives describing its growth abound. DEN boasts among the country’s largest domestic flight networks. It hosts the fastest-growing operation in Southwest Airlines’ 52-year history and is United Airlines’ fastest-growing hub. Coloradans travel by air 3.2 times as much as the United States as a whole does.

As the state’s largest economic engine, generating more than $26 billion annually, the facility’s location almost equidistant from either coast and 500 miles from the closest major commercial airport largely shields it from the backlash of inconveniences caused by ongoing construction.

“Denver is the only airport that serves an economically thriving area,” said Earl Heffintrayer, an airports analyst for Moody’s Investors Service. “While operational challenges are going on, they’ve seen growth at about the national average.”

The city’s decision to fire Great Hall Partners, a public-private partnership between Ferrovial Airports, Saunders Construction and JLC Infrastructure, which will require it to pay a penalty to the group, highlights the challenges of using what’s known as a “P3” to complete airport projects. The $1.8 billion contract included the Jeppesen modernization and a 34-year concessions management agreement.

“We’ve seen the most successful P3 projects on greenfield, or new projects, where there is a lot greater ability to design from scratch and where they aren’t relying on trying to incorporate a previously built project,” Heffintrayer said.

The business community along the Front Range at the base of the Rocky Mountains, which posted the fifth-fastest growth in the nation in the first quarter, is anxiously awaiting the restart of construction in the Jeppesen Terminal. The airport’s location 24 miles northeast of the Mile High City’s downtown and its emphasis on increasing the number of international flights is considered a key driver of this growth.

“It would be hard for me to overemphasize how important the airport is to companies doing business here or looking to do business here,” said Kelly Brough, president and chief executive of the Denver Metro Chamber of Commerce. “This is our port — it’s everything to us.”

On Nov. 6, a City Council committee approved a new program manager, design firm and construction manager for the project. On Monday, the City Council approved a new program manager, design firm and contractor for the project.Airport officials hope to begin work again in early 2020 and finish by 2024.

In the meantime, they concede the stalled modernization effort could cause the facility to slip in passenger rankings that earned it a coveted Skytrax award this year for North America’s best regional airport.

“We are expecting we are going to drop in those ratings,” said Day, the airport’s chief executive. “While we don’t like it, we get it, and I guarantee when we get done we are going to come back and come back strong.”

Until then, Denver’s new beer passport and its canine-therapy squad, which includes 115 dogs representing over 45 breeds and one domestic shorthair cat, will be available over the holidays to soothe harried travelers. To help guide travelers, the airport installed signage and brightly colored floor decals that lead to check-in areas, security, and other popular locations.

The trading-card-toting pets will be joined by a phalanx of volunteer ambassadors armed with small white maps that illustrate how passengers can detour around construction in the middle of the Jeppesen.

Among them is Bill Dawson, who recently celebrated his 15th anniversary guiding people around the facility. The retired furniture entrepreneur estimates he helps up to 400 travelers each shift. Yet confusion caused by construction makes it difficult even for him to distinguish his location.

“I’ve done a lot of running,” he said recently as he double-timed it from securing a wheelchair at Delta’s ticket counter on the sixth floor to his position at the bottom of an escalator near baggage claim on the fifth floor.

“With all the temporary walls, when people ask me a question as I’m walking around,” he added, “I have to look for a door number, or a carousel number, to figure out where I am.”