ALA provided the development of preliminary structural engineering (30% plans) for a cut and cover tunnel, Metro stations and facilities, a maintenance shop, retaining walls, bridges, wayside buildings, and parking garages for Phase II of the Dulles Corridor Metrorail Extension. Bridge assignments included:

• Dulles Metrorail Extension over Centreville Road: Preliminary design plans for the bridge carrying the Dulles Metrorail over Centreville Road near Dulles Airport. The bridge consists of a single 102 ft steel girder span supported by integral concrete stub abutments on two rows of steel H-piles. MSE retaining walls were utilized in front of the stub abutments and as wingwalls.
• Dulles Metrorail Extension over Horsepen Run: Preliminary design plans for the bridge carrying the Dulles Metrorail over Horsepen Road near Dulles Airport. The bridge consists of a continuous steel beam with 3 spans of 35’-5”, 60’-0”, and 35’-5” supported by full height concrete abutments and 2 solid wall piers. Abutments are on steel H-piles with two rows, and piers are on spread footing.

Further, ALA developed preliminary design plans for the property acquisition (ROW) of the project. Permanent easements were designed on the Airport property, Dulles Toll Road, and Dulles Greenway to meet WMATA’s needs for the operation of the Metrorail Extension.

Other services provided by ALA included the airport alternative alignment study; structural design for the Dulles Airport Station including mezzanine, canopy, and ancillary areas; structural engineering for tunnels including a cut and cover tunnel, drafting mined tunnel and other structural work outside the station; and structural design support for station architecture. The project also includes the preparation of plans for the Design/Build package (bridging documents).