Instrumentation & Monitoring
Installation of geotechnical instruments and monitoring of sensor thresholds
Scroll Down
The Challenge
- Monitor movement during excavation
- Enhance safety monitoring to surrounding structures
The East Side Access (ESA) project in New York City connected the Long Island Rail Road’s (LIRR) Main and Port Washington lines in Queens to a new LIRR terminal beneath Grand Central Terminal in Manhattan. Before construction could begin, the project team needed to monitor and measure any movement, settlement, tilt, strain, liquid levels, and induced vibrations from tunneling, excavation, and construction activities at and surrounding the project site.
The Solution
Prior to the start of construction activities, geotechnical instruments were installed above ground and in the subway tunnels to measure movement. Instruments included automated motorized total stations (AMTS) with reflective prismatic targets, manual survey points, inclinometers, extensometers, observation wells, tilt meters, seismographs, dynamic strain gages, and liquid level settlement systems (LLSS). Many of the instruments were designed to be read remotely and automatically, providing alerts about unacceptable movement during construction.
Geocomp also managed the geotechnical instrumentation data on the Manhattan Approach Tunnels and Queens Open-Cut Excavation. Tunnel boring machine (TBM) equipment was used to bore four TBM drives from the existing tunnel under 63rd Street and Second Avenue to the south end of the GCT tail tracks. The work also included excavation of cross passages between the tunnels and a central instrument room. An open-cut structure was created and then decked over to serve as the TBM launch area for the Queens tunnels prior to its permanent use as an interlocking and emergency exit/ventilation facility.
Related Projects
