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Project Profile
U.S. Department of Transportation Headquarters Building – Adjacent Construction Monitoring
Washington Metropolitan Area Transit Authority (WMATA)
Washington, DC
 The
new U.S. Department of Transportation Headquarters Building at the Southeast
Federal Center is within the bounds of the Washington Navy Yard in Washington,
DC. WMATA Green Line tunnels between the Navy Yard Station and the Anacostia
Station lie under the building foot print. The project required an excavation
over the subway tunnels, and FEA provided instrumentation and monitoring services
for the tunnels and associated structures in accordance with the requirements
of WMATA’s Adjacent Construction Design Manual.
FEA provided an instrumentation
program utilizing six robotic theodolites mounted along the tunnel wall that
would sight and locate target prisms around the tunnel cross section at 25-foot
intervals along 2,100 feet of the monitored section of the tunnels. The theodolites,
controlled by two computers placed inside the tunnels, were mathematically linked
to a control network and provided a direct measurement of the change in the tunnel
cross section including the rail bed, making approximately 430 direct measurements
hourly of the tunnel cross section using six instruments. This system reduced
potential measurement errors as well as labor costs compared to normal manual
data collection techniques. The automated system was monitored remotely from
our office with data samplings posted on our website for review. Predetermined
threshold values allowed FEA to alert the contractor and owner of movement trends
during excavation and construction.
Scope Items:
 Design
and install an array of instruments to allow detection of
movement or settlement of tunnel walls and track rails
Automated
remote data collection at FEA office
Real time data sampling
and posting to website for easy access and review by FEA
engineers and the client
Predetermined thresholds for movements
allowing immediate contingency response by contractor to
site conditions
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