The pedestrian walkway connecting the Main Terminal to Concourse B is underground. It was constructed by excavating access shafts, then tunneling to connect the shafts. The outline of the future tunnel is visible on this shaft wall. Photo from June 2001.

View looking down from ground level into an access shaft, with pedestrian tunnel visible. After the tunnel is fully constructed this area will be covered up with earth. Photo from June 2001.

From the bottom of the access shaft, the worklights are visible inside the pedestrian tunnel. Photo from June 2001.

This area is where the pedestrian tunnel will join with Concourse B. Concrete walls surround this below-ground structure. Photo from 2001.

Inside the pedestrian tunnel after it was excavated and lined with an outer protective layer between the tunnel and the earth. Photo from June 2001.

Additional layers of lining inside the pedestrian tunnel take shape. Photo from November, 2001.

Working inside the pedestrian tunnel between the Main Terminal and Concourse B. Photo from November, 2001.

Adding interior elements to the tunnel such as a drop ceiling, lighting, walls, and moving sidewalks to the pedestrian tunnel. Photo from 2002.

Managers of Dulles Airport, the Metropolitan Washington Airports Authority, and the Board of Directors cut the ribbon opening the walkway. It connects the Main Terminal to Concourse B. Photo from November 2002.

First day the new pedestrian walkway was in service, looking from Concourse B back towards the Main Terminal. Photo from November 2002.

First day the walkway was in service, looking from Main Terminal towards Concourse B. Photo from November 2002.