Beneath a busy interchange on top of the highest point in Tysons Corner, Va., crews are mining a tunnel that will carry the Dulles Corridor Metrorail tracks from Route 123 to Route 7. Working two 12-hour shifts per day, crews began tunnel construction, using the New Austrian Tunneling Method to mine the first of two tunnels, the outbound segment. Construction will start on the inbound tunnel in the coming months.
The tunnels when completed
will be 2,400-feet long. Construction is not visible to drivers because it is
behind a crew fence along Route 123 near International Drive.
During construction, crews
are using sensor technology to monitor the tunnel and nearby roads for any
movements. Soil in the tunnel area is a combination of gravel, clay and sand.
Businesses and residents of
the Tysons area have been told to expect major traffic pattern changes all
along the one-mile rail construction zone of Route 7 from the Dulles Toll Road
east to Route 123 in the coming weeks. For example the service roads along the
edges of the east and westbound lanes of Route 7 will be closed so that the
edges of Route 7 itself can be pushed out to the edges of the service roads and
beyond to make room for construction of the rail line and stations in the
median of the road bed.
Near the two stations to be
built along Route 7-Tysons Central 7 (near SAIC and Marshalls) and Tysons West
(between Spring Hill and Tyco Roads), the eastbound lanes will balloon out into
the parking areas of some businesses. Also, along the eastbound lanes, crews
will be building retention walls to support the new roadbed as crews must build
up many existing service roads to the levels of Route 7.
work is beginning near all five station sites: four in Tysons and one at Wiehle
Avenue in Reston. Work is most visible near the Wiehle Avenue Station in the
middle of the Dulles International Airport Access Highway between Wiehle Avenue
and Reston Parkway and at the Tysons East Station at Route 123 and Scotts
Crossing Road near Capital One.
Along the Dulles Connector
Road, near I-66, piers and caissons are sprouting up to support a flyover for
the rail line from the Orange line to the Connector Road. Pile driving to
support new bridges at Idylwood and Magarity Roads and Pimmit Run continues.
Rail construction trucks
are using I-66 inside the Capital Beltway during restricted day and night
hours. Up to 74 trucks per day will be allowed to the Lee Highway/Washington
Boulevard exit to turn around and go westbound on I-66.