Dulles Corridor Metrorail project reached a major milestone recently, as excavation of a 2,400-foot tunnel under the busy Tysons Corner area of the Washington, D.C. suburbs began on October 12. This section represents the most complex engineering and construction challenge of the project.
The tunnel will connect two of the future Metro stations: Tysons Central 123 and Tysons Central 7. Construction crews will be using the cut and cover method called the New Austrian Tunneling Method to excavate the two bores of the tunnel. The excavation begun on the east side of the outbound tunnel; after completion of the first 150 feet, the excavation will follow on the inbound tube always keeping the 150-foot distance. Sensor technology will be used to monitor the tunnel and the surrounding area for possible ground movements. The tunnel will be built as the cars are driving above the tunnel through Tysons Corner, and as the businesses and residents are going about their daily routines.
Construction of the project began in March, 2009, with the signing of a $900 million grant from the U.S. Department of Transportation. “This milestone definitely marks a great step in the construction phase of the project. We are proud to be part of the transformation of transportation options in Northern Virginia,” says George Morschauser, the project's executive director. “The project team is focused on delivering this project safely and with the highest quality.”
Phase 1 of the project, currently being constructed by Dulles Transit Partners, led by Bechtel, will include five new Metro stations and 11.5 miles of new track. When Phases 1 and 2 are completed, it will add 23 miles of track to the existing Metropolitan Washington, D.C. area Metro system, and will extend the system to Dulles International Airport and on to Loudoun County. The project is owned and managed by the Metropolitan Washington Airports Authority.
The Washington Post
featured tunnel excavation efforts at Tysons Corner on October 18. Read the full article
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Dulles Transit Partners