Dulles Metrorail Extension Phase I

ALA provided structural engineering services for at-grade stations at Wiehle Avenue and Tyson’s Central 7.  The structural components include a steel roof vault, canopy, mezzanine level concrete deck supported on structural steel framing, reinforced concrete columns, platform slab in service and non-service areas, foundation and station barrier walls.  Analysis and design of various rail alignment alternatives also were conducted.

Utilities Relocation

Additionally, ALA was responsible for relocation of utilities on the Route 7 and Route 123 Corridors which included relocation of existing water and sanitary sewer lines; plan/profile layout of proposed water lines; plan/profile layout of proposed electrical lines (both for train control and general distribution lines); and plan/profile layout for proposed communication lines.  The utility relocation in the Route 7 and Route 123 corridors were particularly complex due to the large number of existing and proposed underground utilities.

Drainage Systems

The firm also managed a team of drainage engineers responsible for the design of all of the Project’s SWM facilities and drainage systems throughout the 15-mile corridor. The runoff generated in guideways is collected and directed to a series of Infiltration Basins (Rain Gardens) through downspouts located at every pier. ALA used LID SWM measures to control peak discharges by increasing the time of concentration and storing volume to protect the downstream channels as well as provide BMP treatment by allowing this runoff to be filtered and/or infiltrate the ground. This approach achieves the three goals in LID design: reducing peak discharges, providing high pollutant removal and protecting eroding urban streams.

Location: Fairfax County, VA


Services Provided: Structural Engineering, Utilities Relocation, Drainage Design and Stormwater Management/LID/Green Infrastructure Design