A July 7 article on improvements at Dulles International Airport reported incorrectly that mobile lounges have been shuttling passengers between the main building and the midfield terminal since the airport opened in 1962. Although mobile lounges have been used since the airport opened, the first midfield concourse at Dulles opened in 1985. (Published 7/8/04)

The future of Dulles International Airport, which includes a train circling the airport, new runways and gates and a cloud-kissing control tower, looked like little more than piles of dirt and skeletal construction yesterday as the $3 billion project neared the halfway point.

But passengers will start seeing dramatic changes as soon as Thanksgiving, when a 1,000-foot moving sidewalk opens that will connect the airport's main building to concourses A and B. The underground passageway will allow travelers to walk -- or run frantically -- to gates, freeing them from having to take the moon-unit-like mobile lounges that have been shuttling passengers between the main building and the midfield terminal since the airport opened in 1962.

By 2009, an automated, underground train system, similar to ones in the Atlanta and Denver airports, will provide another link between Dulles's main building and the far-off ones where flights begin and end. Those changes will relegate the mobile lounges to a secondary role, although airport officials said they will not disappear entirely.

The construction at Dulles comes at a time when all three Washington area airports are returning to levels not seen since before the terror attacks of Sept. 11, 2001, and Baltimore-Washington International Airport is undergoing a $1.8 billion expansion.

"We're building Dulles for the demand we see in the future," said James E. Bennett, president and chief executive of the Metropolitan Washington Airports Authority, who took the media on a tour of the construction yesterday.

Activity at the airport yesterday included the reconstruction of one of its three runways. The runway has been out of service since April and has contributed to flight delays during the heavy summer season, but airport officials said they plan to have it operating again by mid-August when start-up Independence Air plans hundreds of additional flights each day.

A fourth runway is expected to open in 2008. And a 325-foot control tower -- twice as tall as the existing one -- is slated for completion in 2006.

Expansion projects completed at Dulles include two new parking garages that added 8,500 spaces. The garages have walkways to the terminal. Underway are renovations of ticketing and baggage claim areas and construction of more gates.

Traffic at "Dulles is growing very rapidly," Bennett said.

Airport officials said yesterday that traffic at Dulles increased 17 percent, from 16.8 million to 19.7 million passengers, in the 12 months that ended in June 2004 from the same period a year earlier. They said the number is expected to skyrocket in the next 12 months to 26.3 million passengers, based largely on the impact of Independence.

Increased activity at Reagan National Airport has filled parking lots on some days, and airport officials said the number of passengers is expected to hit the 15 million mark this year -- about where it was before the terrorist attacks.

BWI officials said the airport reached pre-Sept. 11 levels last year and has experienced a double-digit percentage increase in volume since then.

The $1.8 billion expansion of BWI will triple its parking capacity, widen access roads and add more gates, terminals and services. Most of the parking upgrades have been completed, and the terminal improvements are scheduled to be finished by the summer of 2006.

The billions of dollars in improvements underscore the importance of the airports to Virginia and Maryland. Leaders in Virginia have linked the booming economic development of the Dulles corridor directly to the airport, and their counterparts in Maryland have said that expanding BWI is critical to growing the state's business base and competing with the Old Dominion.

Expansion at Dulles began in 2000 and was reassessed after the tremendous decline in air travel that followed the Sept. 11 attacks. Planners decided to put off indefinitely work at concourses C and D and construction of another concourse. They also scrapped plans for a train connection to the international arrivals terminal. A walkway from the main terminal to concourses C and D has also been delayed until they are rebuilt.

Nonetheless, the airport is rife with temporary changes. The airport has moved the docking locations for mobile lounges, as well as screening checkpoints and walkways.

While excited about improvements at Dulles, many passengers are not thrilled about the inconveniences of construction.

"It looks like I'm going through a maze," said Naresh Rangwani, a regular flier who landed on an early afternoon flight from Houston. "I'm going up and down and up and down, and then some steps come back up. I liked it the way it was before."

A pedestrian tunnel connecting the main terminal to Concourse B is one of the changes underway as part of the expansion of Dulles International Airport. The underground rail system now under construction at Dulles will largely replace the airport's mobile lounges.Tom Sullivan, a spokesman for the Metropolitan Washington Airports Authority, holds a rendition of the control tower being built at Dulles.