Washington Dulles International Airport 1980s the original design, featuring mobile lounges to meet each plane, was no longer well-suited to Dulles' role as a hub airport. Instead, midfield concourses were added to allow passengers to walk between connecting flights without visiting the main terminal. Mobile lounges were still used for international flights and to transport passengers between the midfield concourses and the main terminal. An underground tunnel (consisting of a passenger walkway and moving sidewalks) which links the main terminal and Concourse B was opened in 2004. The Metropolitan Washington Airports Authority (MWAA) began a renovation program for the airport including a new security
Washington Dulles International Airport mezzanine with more room for lines. A new train system, dubbed AeroTrain and developed by Mitsubishi, began in 2010 to transport passengers between the concourses and the main terminal. The system, which uses rubber tires and travels along a fixed underground guideway, is similar to the people mover systems at Singapore Changi Airport, Hartsfield–Jackson Atlanta International Airport, and Denver International Airport. The train is intended to replace the mobile lounges, which many passengers found crowded and inconvenient. The initial phase includes the main terminal station, a permanent Concourse A station, a permanent Concourse B station, a permanent midfield concourse station