Dulles Corridor Metrorail Project

Virginia Department of Rail and Public Transportation and Metropolitan Washington Airports Authority


Metrorail Tunnel and Station Design:

The Dulles Corridor Metrorail is a new 23 mile (37 kilometer) line extending the metro service from an existing line at the East Falls Church Station in Fairfax County to Route 772 in Loudoun County, Virginia. The project will be constructed in two phases with scheduled service for Phase 1 by 2013 and Phase 2 by 2017. The corridor will feature running tunnels at Tysons Corner (Phase 1) and running tunnels and a mined New Austrian Tunneling Method (NATM) underground station at Washington Dulles International Airport (IAD) (Phase 2).

Gall Zeidler Consultants (GZ) provided tunnel and station design services from the conceptual to final engineering stages of the project for Phase 1 and the conceptual design for Phase 2 tunnels and station caverns. This expertise included design drawings, specifications, structural calculations and construction cost estimates. Preliminary design activities included Tunnel Boring Machine (TBM) selection for both soft ground (Earth Pressure Balance Tunnel Boring Machine) and hard rock conditions (mainframe gripper type Tunnel Boring Machine), in addition to one-pass and two-pass tunnel lining designs.

The NATM tunnel at Tysons Corner earned an Excellence in Automation Award from the American Society of Civil Engineers (ASCE) and was a finalist for the International Tunneling Awards in 2011. During construction of the soft ground NATM tunnels at Tysons Corner, GZ provided construction support and inspection services.

Vienna, Virginia
2004 – Present
Metrorail Tunnels at Tysons Corner and Running Tunnels and an Underground Station at Dulles International Airport
Two Single Track Tunnels 1,700 feet (520 meters) Each at Tysons Corner and Two Single Track Tunnels, 1.96 miles (2,800 meters) each at Dulles Airport
21.5 foot (6.5 meter) Diameter Running Tunnels and 40 foot (12.2 meter) Springline Diameter for Mined Station Tunnels at Dulles International Airport
Fill, Residual Soils, Saprolite, Claystone; Balls Bluff Formation (Mudstones and Siltstones)
Approximately $5 Billion
Dulles Transit Partners (DTP), a Joint Venture of Bechtel, Inc. & Washington Group International
The Metropolitan Washington Airports Authority (MWAA)