CHANTILLY, Va. (AP) After nearly eight years of digging and more than a decade of planning, Washington Dulles International Airport unveiled a $1.5 billion train system designed to help travelers reach their gates more quickly.

The new underground train system, called AeroTrain, replaces the airport’s unique, bulky “mobile lounges” that have shuttled passengers from the terminal to the gates since the airport opened in 1962.

While the use of the mobile lounges will be curtailed, they will remain in use for international arrivals and at the airport’s “D” gates for the foreseeable future.

The new train system is designed in anticipation of expanding traffic at Dulles, a United hub and the largest of the three airports that serve the greater Washington region.

The future planning is such that the train station serving the airport’s “C” gates is built at the future site of the those gates, slightly overshooting the building that serves the existing “C” gates. Passengers will use a moving walkway to backtrack to the existing “C” gates.

“This is about the future of Dulles,” Jim Bennett, director of the Metropolitan Washington Airports Authority, which runs Dulles and Reagan National airports, said at a preview tour of the system.

At $1.5 billion, the AeroTrain system is essentially the final piece of a $3 billion-plus capital improvement program at Dulles initiated a decade ago. It includes two new parking garages, a fourth runway, a new control tower and moving walkways that carry passengers from the terminal to the “A” and “B” gates if they opt not to use the trains.

Construction on the AeroTrain system began in 2002.

The capital program began a decade ago, before the Sept. 11 attacks disrupted the airline industry. The airports authority put its construction program on hold for about a year after the attacks, but eventually decided that in the long term demand would continue to increase in this market.

The improvements were paid for by issuing bonds, and the money is recouped by charging fees to the carriers that operate out of Dulles. Despite the extensive improvements, airport manager Christopher Browne said the fees charged by Dulles to the carriers — which are ultimately reflected in the ticket prices paid by travelers — are competitive with those charges by other airports of its size.

The next major expansion will be the construction of a new Midfield Concourse that will eventually be home to the airport’s “C” and “D” gates and will allow the train system to run at maximum efficiency. Bennett said it is too early to know when that concourse will be built because the airport is still negotiating with its largest tenant, United Airlines.

The new underground train network is nearly 4 mi. long and runs 29 cars that travel up to 42 mph. The airport expects the average wait time to be less than two minutes, and it takes the train just more than a minute to travel between stations.

The train cars, built by Mitsubishi Heavy Industries, run on rubber tires and are similar to systems used in Hong Kong and Tokyo.

Use of mobile lounges will be cut roughly in half, and nearly half of the 100 or so mobile lounge drivers opted to take a buyout offered by the airports authority. The AeroTrain system is operated without drivers.

Taking so many mobile lounges out of service also will reduce congestion on taxiways, where the lounges often had to yield to aircraft in making their way from the terminal to the gates.

Today's top stories

TxDOT's $802M I-30 Project in Dallas Area Makes Strides

Trench-Related Fatalities Decrease: Common Ground Alliance Celebrates Progress, Commitment to Safe Digging

New Horizon at Nashville's Airport Showcases Continuing Expansion

Caterpillar Invites World's Most-Skilled Operators to Forge Their Legacies Through Third Global Operator Challenge

VIDEO: Electric Demolition Excavator Gives Robles1 New Edge

After Years of Planning, Construction, New River Bridge Open to Connect Vermont, New Hampshire

Idaho Transportation Department Maintenance Team Prevails at National Snow Roadeo

Skanska Names Trevor Wyckoff VP, GM for Ore., SW Wash.