The biggest airport in the US is getting bigger. With its 16,000-ft. sixth runway-the longest commercial landing strip in the nation-a year old, Denver International is starting on the first terminal expansion of its nine-year life. It will spend about $100 million to build an extension to Concourse A, chiefly for Frontier Airlines, and another $45-$50 million on better facilities for United Airlines' Regional operations at the end of Concourse B.

The United work is part of a deal under which DEN's dominant carrier agreed to retain its leases until at least 2025. Another $15 million is being spent to reconfigure the airline's ticket lobby. The airport also has begun work on an in-line baggage screening system expected to cost some $108 million and hopes to get $71.25 million of that back from the Transportation Security Administration.

Traffic is up more than 15% this year. "If this trend continues and there are no major disruptions," says Vicki F. Braunagel, co-manager of aviation, DEN could log more than 40 million passengers in 2004. In an arrangement unique to Denver, Braunagel shares the airport manager's job with Turner W. West. She is responsible for business and financial matters, West for maintenance and operations. There is no director of aviation.

The airport's record year was 2000, with 38.75 million passengers. The 2003 total of 37.5 million made it the 10th busiest in the world. Its passenger transfer rate is 45%, chiefly by United and Frontier, says Charles Cannon, assistant deputy manager-aviation public affairs. UAL and its Regional partners carry 62% of the airport's total traffic, Frontier and its Regionals 17.5%.

DEN has become a darling of low-cost carriers, with six of the seven officially designated LCCs operating there (Southwest Airlines is the exception). In the past two years, total LCC departures increased 65.3%; between March 2001 and June 2003, average fare dropped 24% to $175.

LCCs are flocking to the airport in spite of its high operating costs. The landing fee is more than $3 per 1,000 lb. of landed weight-which Braunagel notes is a significant decrease from earlier levels-space rentals top $100 per sq. ft. and cost per enplaned passenger is in the $14-$15 range. UAL and Frontier officials interviewed for this article commented on the airport's high costs.

But, Braunagel claims, "It's a very efficient operation" for the airlines. "We certainly have a good market here. There's a higher propensity to travel" than in many other cities. "The airfield provides plenty of capacity for traffic growth, and the airport is well located." And, she notes, "We're getting lower-cost every day." Airline charges are adjusted based on total airport income, and airlines get services such as fueling and terminal maintenance that are not always provided by airports, she points out.

Nearly all of the 89 gates are leased. United's lease is the longest while Frontier's runs until 2010. The airport controls a few gates on Concourse C and will get two of the new A gates when the Frontier expansion is complete.

The new facilities for United at the end of Concourse B will replace a pair of barebones boarding corridors now used by its Regional partners. Passengers are kept in the main holding area until flights are ready, then escorted down escalators and elevators and through a long hallway to outside boarding positions. This ramp can accommodate up to 36 turboprops.

New construction will provide a horseshoe-shaped structure with seating, concessions and restrooms. The legs of the horseshoe will be farther apart than the existing corridors to increase aircraft maneuvering space, and a taxiway will be added. Present planning calls for 38 parking positions and ground-level boarding, although the facility is designed so loading bridges can be used. Providing bridges "hasn't been precluded," Kenneth A. Bostock, UAL's Denver GM-customer services, tells AE&T. They could be in place when the new gates open or fitted later, he says. Construction started in the early summer and will be finished in late 2005 or early 2006, West says.

"As we look forward," Bostock notes, "the main facility changes will be on the RJ side. We expect to be operating more RJs in the future," which will enable the carrier to increase frequencies, supplement existing service and open new markets. United has a total of 43 gates at DEN, 36 on B and six on A. It operates 255 daily mainline flights, including 34 by Ted, and 163 United Express trips flown by Air Wisconsin, SkyWest and Mesa.

Ted is making money, flying with loads above 90%, but the flight total "can't go up until we decide whether to get more aircraft" for the LCC, Bostock explains. United put the Ted operations on the A gates "to create a camaraderie of our employees" working on the new unit.

The airport is spending $15 million to reconfigure UAL's section of the ticket lobby, eliminating flow-through check-in counters to make way for up to 86 self-check units. There will be no fixed agent positions; agents will circulate to help passengers as needed. Dynamic signage will permit designating areas for international, first-class and other groups of passengers. "About 65% of our passengers use alternative check-in procedures," including the Internet and curbside stations, Bostock notes. Curb check-in positions will be added, and "we will actually give some lobby space back to the city." This work is expected to be completed around late March.

The lobby project is tied in with the in-line baggage screening system that eventually will be installed throughout the terminal. In-line screening will "mesh in" with UAL's automated baggage distribution system, with bags going through TSA scanners first, then to the UAL equipment. "The baggage system is a lot better than it used to be" (AE&T, Winter 1998, p. 11), but "it's a monster machine to keep running," Bostock concedes. "We have to make some decisions relatively soon about long-term plans for that system . . . maybe to modify the design." United has upgraded its barcode readers and at least for the time being will continue to use paper luggage routing tags.

Two years ago the airline started using the automated system to transfer outbound baggage between gates. Bostock points out that it was designed to do this, so "we're now getting more utility from it." It never has been used for inbound luggage. "We need to look at replacement and maintenance costs [of the existing equipment] versus replacement of elements of the system. When the city puts in a baggage system for the other airlines, United will look at it."

The Concourse A project is the first expansion of an original DEN concourse and will provide six new gates plus ramp loading positions for Regionals. Cost probably will top $100 million, Braunagel says, and it will open in late fall 2005. Four of the new gates will be used by Frontier, giving the airport's second-largest carrier a total of 18 mainline gates and five Jet Express positions. Frontier now is operating from 16 gates and four ramp Express positions running 106 mainline and 25 Express flights daily.

Tim Thornton, Frontier's director-customer care and service for the Denver hub, looks forward to the expansion to relieve crowding in the concourse. The carrier and the airport spent $5 million to build 200-ft. enclosed walkways from the end of the concourse to two aircraft parking positions on the ramp that otherwise would have to be ground-loaded. These will be used until the new gates are available.

"Frontier will grow here," Thornton predicts. He would like eventually to take over the United gates on Concourse A. Being closest to the main terminal gives the carrier several advantages, he notes: "We have a 30-minute check-in cutoff for passengers. Airlines in Concourse C have a 45-minute cutoff." Frontier passengers can ride the underground train to the concourse or walk through an enclosed connector with views of the ramp and aircraft taxiing under the elevated corridor.

Thornton would like to change the baggage handling system for airlines other than United. When the airport opened and it was decided that the automated system would serve only United, an alternate method was improvised for the other carriers that involved putting bag makeup in the front of the parking garage. Tugs, carts and a lot of employees move the bags around. With in-line screening, bags will be scanned below the check-in counters, then go out to the parking garage for makeup and from there to the gates.

"I hope the solution will be in new technology-a high-speed belt to the concourse," he says. "The city is looking into this." Existing tunnels and tracks could accommodate this equipment, he adds. He thinks it would take at least five years to put into place and knows it would be expensive, but it would produce significant labor and GSE savings over time. A proposed automated baggage handling system to serve Concourse A airlines would cost $20-$25 million, he says.

In-line screening is being added in segments, with the entire $108 million project scheduled for completion late next year, making DEN the first major US airport to handle all outbound luggage this way. The first section serves about 48 agent positions in a new group of check-in counters in the southeast corner of the terminal used by American Airlines and charter carriers. TSA is using this first unit to beta-test various types of explosive detection equipment. The airport absorbed the $13 million cost of the initial module but, as mentioned, hopes to get $71.25 million back from TSA for the whole system. The agency will provide the 50 explosive detectors, expected to cost about $50 million in total.

Denver's master plan always has included a terminal hotel but there are no immediate plans to construct it. "We're going to be very careful about going ahead with it" because the airport would have to take on more debt to build it, Braunagel explains. It would be connected to the terminal by an enclosed corridor with moving walkways and would provide some 500 rooms plus meeting space. The hotel will be owned by the airport and operated by Westin.

DEN also is looking at increasing FIS capacity to accommodate growth in international traffic. Noting that "we need more bag claim space there," Braunagel says the addition would cost $4-$6 million. Current new projects include RJ holdrooms at the east end of Concourse A costing about $1 million and a $5 million firehouse for the new runway, West adds.

No additional construction is anticipated in the short term, but the master plan calls for a second terminal, 12 runways and 300 gates on the 34,000-acre property at full build-out. The airport then would be scaled for 100 million annual passengers. Design capacity of the existing facilities is 50 million.

Bostock and Thornton expect their airlines to continue to thrive at Denver. "We're planning for the future," says Bostock. "We've been set up for success here. We really have a gem here."