It's 9 a.m. and the parking garages at Denver International Airport are already filled to capacity, as are the economy spaces and the main shuttle lot.
The crowds at the airport's two main security checkpoints curl around the roped cues, spilling into the terminal and snaking past the baggage carousels.
There is little relief on the other side of security.
Lines 20-people deep branch out from concourse restaurants and fast-food stands, and passengers are sprawled on the floors near the packed gate areas.
This was the scene at DIA on a Saturday in August, but it isn't limited to just this one morning.
There have been plenty of days like this in recent months.
Twelve years after handling its first flight, DIA finds itself at a critical juncture, bursting at the seams with passengers, scrambling to keep pace with breakneck growth and edging closer to its maximum capacity.
"I'd say at least once or twice a week we're filling up our parking lots, and we have to open the overflow" shuttle area, said DIA Manager Turner West. "That used to be rare. It's just one example of how the system is stressed. It's not just parking. It's security and roads and gates and concessions."
To address its rapid growth, DIA is undergoing a comprehensive review of its long-range master plan and has launched numerous expansion and improvement projects to ease congestion in the near term. It plans to spend more than $1 billion through 2013 on its concourses, concession areas, security checkpoints, parking lots and baggage system.
But it's a daunting task, especially in a volatile, vulnerable industry fraught with unpredictable swings in demand and financial instability.
The airport's success in keeping up with growth - and keeping a lid on the fees it charges airlines - is vital for the region because it will affect everything from airline service to economic development. It's also of the utmost importance to travelers, many of whom have come to depend on moving through DIA quickly, efficiently and, in recent years, cheaply.
"The risk of doing it wrong is that Denver's future growth will be threatened," said John Kasarda, a management professor at the University of North Carolina at Chapel Hill's business school who has studied airport growth. "The community has to know that the livelihood of the entire state is based on air travel. The airport is the lifeblood of 21st century metropolitan economies."
Surprising growth rate
It wasn't that long ago when DIA felt cavernous.
It rarely was difficult to find a parking space in 2003. Security lines were almost nonexistent. And you easily could find a seat in the gate areas.
So what happened?
The burgeoning passenger numbers caught airport and city officials by surprise.
DIA's original master plan outlined a rough blueprint for growth until the airport hit about 50 million passengers annually, when it would have to consider a major expansion phase.
The airport had posted solid passenger gains throughout the late 1990s, but the 2001 terrorist attacks brought that to a grinding halt.
Traffic and airline operations (takeoffs and landings) at DIA fell to 1997 levels. United Airlines tumbled into bankruptcy, throwing the future of Denver's largest airline into doubt. Demand slumped nationwide, and some observers predicted it would take many years to get back to pre-2001 levels.
DIA had to shelve most of its expansion projects because the uncertainty was too great.
Demand, though, began a steady march upward in 2003, and by the end of the next year DIA was setting passenger records. Homegrown Frontier Airlines fueled much of that growth, gaining market share and adding flights and destinations while its larger competitor United cut back.
Airport officials, though, thought it still would take years to hit the 50-million mark.
That changed late in 2005, when Southwest Airlines announced it would come back to Denver after a 20-year hiatus. The news - coupled with the emergence of United from bankruptcy - set the airport in motion, reviving serious attempts to update the master plan.
"It's very difficult to expand and plan when you don't know how the industry is going to shake out," said Rick Busch, DIA's director of planning. "But United came out of bankruptcy, and demand recovered. When Southwest came in, we said, 'Hey, we gotta get going on this.' "
Southwest transformed the landscape in Denver, making it one of the few cities with three airlines aggressively battling for market share. That led to lower prices, helping draw even more people to the skies. United also added flights and struck a deal to route more passengers through Denver, while Frontier kept growing, as well.
The result: DIA's passenger traffic jumped 9.1 percent last year, tying it for the third-fastest growing airport in the world. The pace has slowed this year. But DIA is expected to come in just shy of that 50-million mark - years ahead of schedule.
There's no doubt the passenger surge has been good news for the airport, particularly from a financial perspective.
DIA's revenues have soared as the airport gleans more money from food and beverage sales, parking fees and other non-airline sources. It's been able to pay down and refinance its debt, saving millions of dollars a year in interest payments. It's been able to lower the fees and rent it charges airlines, which encourages them to expand. Last year it posted a record profit, bolstering its financial strength.
Airline costs per enplaned passenger - a measure of how much carriers pay to operate at the airport - have plummeted to about $11.16 compared with more than $16 a decade ago.
That decrease was a key reason Southwest returned to Denver.
But the spike in passengers is stressing the airport's infrastructure.
Nearly 15 million more people annually are using the airport than just five years ago. On top of that, DIA is attracting more local passengers than connecting ones - the opposite of how it was structured to operate. More local travelers means more people using access roads, ticket counters and security checkpoints.
Take the parking situation.
The airport is having to open its overflow lot, Mount Elbert, more often than in the past because the Pikes Peak shuttle lot increasingly is hitting its capacity. Airport officials say that Mount Elbert will be operating full time by the end of the year.
An even more pressing issue is gates. DIA is running out of available ones, which could limit expansion by current tenants and deter new airlines from coming to Denver. At its recent budget presentation to Denver City Council, DIA officials said that the gate situation is "more constrained" than they originally thought.
It's a growing problem at airports across the country. Demand has been rising nationwide, and other major airports are scrambling to expand as well.
Those airports, though, face huge costs and other challenges because they're already jutting up against neighborhoods and other development.
In that respect, DIA is in an enviable position. Once heavily criticized for being in the middle of nowhere, the airport has plenty of room to grow.
"Overcapacity is a front-burner issue right now," said Pauline Armbrust, publisher of industry trade publication Airport Revenue News. "A lot of airports are bursting, and a lot don't have ways to expand because they are limited by land mass and space. DIA doesn't have those concerns."
DIA has centered much of its focus during the past two years on expansion, spending 25 percent more in 2006 on capital improvement than in the previous year.
To reduce congestion and prepare for future demand, the airport has added two more temporary gates on Concourse C and recently launched a large project to add 10 more gates and a regional jet facility.
It has brought in more train cars to ferry passengers between the terminal and the concourses and is building a new parking garage. It constructed a new $42 million wing on Concourse B for United Express flights and is revamping its concessions program.
The airport has cemented plans for a long-awaited terminal hotel and galvanized retail development on Pena Boulevard.
"I think the leadership in Denver and at the airport have certainly helped position DIA to be able to accommodate 50 million passengers ahead of schedule," said Mary Rose Loney, an industry veteran who heads a public-private organization that works to promote airport issues. "Nobody's been turned away, and that's a good thing."
But the work is just beginning.
"We've taken care of the easy, incremental stuff such as adding a parking garage or a train car," said Busch, DIA's planning director. "We're running out of easy solutions."
So the airport is gearing up for its largest expansion and upgrade phase since opening.
DIA is issuing more than $1 billion in bonds to pay for capital expansion. Projects cover everything from bolstering snow-management plans and improving restrooms to adding more concession and seating areas, enhancing landscaping and constructing a new baggage system.
It's finalizing plans to accommodate a new Regional Transportation District rail station - a project that will cost $57 million - and is preparing to add security screening lanes and more checkpoints in the next few years.
"These are all of our immediate needs, the things we've identified as important, looking just a couple years out," said Sally Covington, DIA's deputy manager of aviation, public relations and marketing.
The airport also is taking a comprehensive look at its long-range plan for the next 20 or 30 years, including determining when it might need a fourth concourse and more runways.
DIA now faces the challenge of keeping up with demand without outpacing - or underestimating - it.
The fallout if DIA miscalculates?
If it grows too quickly and demand doesn't pan out, the airport might have to pass more costs onto airlines. That could lead to higher fares and less service.
If it doesn't grow quickly enough, DIA could become a crowded, congested, inefficient airport, which could deter businesses from setting up shop or expanding here, thus making the travel experience miserable.
"If you don't grow in conjunction with demand, then you have those situations at other airports where the security lines are always horrendous and the concessions aren't up to par and the whole thing starts to break down," said Armbrust of Airport Revenue News.
A lingering question is how DIA will pay down all its new debt.
Some of it will come through higher fees to airlines, which DIA has been aggressively trying to minimize.
The airport estimates that costs per enplaned passenger could rise from $11.16 this year to $15.01 in 2013, according to its bond prospectus. That increase could deter airlines from expanding or coming to DIA in the first place.
For an airline the size of Frontier, a $4 increase per passenger would translate into an additional $40 million this year. The Denver-based carrier called DIA's projected increase "problematic" because the airport already has higher-than-average fees.
"Anytime it becomes more expensive to handle a customer at DIA, it can (stifle) growth," said Chris Collins, Frontier's senior vice president of operations. "If our rates go up, that's bad for all airlines."
Still, other major airports nationwide are facing more severe capacity constraints, and many have embarked on massive expansion plans. Most of those airports don't have any space left, so their construction costs are much higher.
"We're seeing a lot of larger airports moving toward the $10 to $15 range" in cost per enplanement, said Pete Stettler of Fitch Ratings, which has given DIA's bonds strong ratings. "They're having to expand as well. So DIA in the ($15) range is not terribly alarming."
While passengers might think DIA has done too little, too late, Stettler says it's the financially prudent way to grow.
"You want to make sure the momentum is there before you undertake expensive capital projects," Stettler said. "You want to make sure that what you're doing is prudent and can be supported by demand. These things are large, complex and expensive."
Airport officials say they understand the importance of keeping costs down. They've been looking for new ways to bolster non-airline revenue from parking, expanding oil and gas drilling and spurring development of a pet kennel on airport land.
"The old model of 'well, we'll just rate-base these costs back to the airlines' is not going to work," Covington said. "We can't do that anymore because the airlines can't pay it."
The more revenue DIA takes in, the more it can pump into defraying the costs of expansion projects.
Perhaps the most difficult challenge, though, is dealing with volatility, especially considering that it takes years to plan, design and construct expansion facilities and upgrades. Another terrorist attack or an economic downturn or a geopolitical event could impact demand immediately and drastically.
The key, DIA officials say, is being able to adapt to market changes.
"Maintaining flexibility in uncertainty is our biggest challenge," Busch said. "We want to make the best educated move we can to be efficient and to optimize existing facilities before we start building more. It's like playing a game of chess, and we have to figure out the best move to make."
Where will the $1.2 billion go? Denver International Airport plans to issue $1.2 billion in bonds in coming years to fund a variety of projects as it seeks to accommodate growth both inside the airport and out.* Some projects on the agenda:
Involves adding 10 gates onto Concourse C and building a commuter facility that can handle 23 regional jets, similar to the one DIA recently built on Concourse B. Also includes a taxi-lane extension
* Estimated cost: $266 million
* Estimated completion: spring 2010
Involves expanding and adding security lanes and possibly creating another screening area in the main terminal
* Estimated cost: Up to $6.7 million
* Estimated completion: By 2013
Involves building parking garages near the airport's main terminal and a third shuttle lot, adding thousands of new spaces
* Estimated cost: $124 million
* Estimated completion: One new garage should open later this year; other expansions to be completed by 2013. BAGGAGE
Involves building a new system to route outbound and inbound luggage using conventional methods such as conveyor belts. Also involves upgrading baggage sorting and claim carousels and moving explosives detection equipment from Concourse B to the terminal
* Estimated cost: More than $90 million
* Estimated completion: By 2013
Involves upgrading the computer hardware and software that routes the underground trains shuttling passengers between the main terminal and the concourses. Also involves extending the tracks south of the terminal to accommodate more trains
* Estimated cost: $25 million
* Estimated completion: By 2013
Note: *Some Of Dia'S Projects Include Money From Federal Grants. Source: Dia