Reducing Construction Interference When Implementing Geotechnical Instrumentation and Monitoring in Urban Excavation Projects-Paper

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Urban deep excavations require geotechnical instrumentation and monitoring (I&M) to protect shoring, nearby buildings, roads, and utilities. Yet instrument installation, access, permits, cabling, maintenance, and coordination can delay construction or interrupt monitoring. This paper describes technologies and practices intended to reduce those impacts while maintaining reliable, continuous data.<br /><br />The approaches include automatic motorized total stations (AMTS) equipped with in-body cameras and automatic leveling devices (ALDs). Cameras let operators remotely commission prisms and inspect sightlines, while ALDs correct instrument tilt without requiring site access. Reflectorless AMTS measurements avoid installing prisms on roads or private property, though they generally measure movement in one direction and depend on suitable surfaces and measurement conditions. LoRa-based wireless sensors reduce cabling and data-acquisition equipment, and can communicate through difficult underground or obstructed environments with low power use.<br /><br />The technologies were applied at the New Century Plaza excavation in Los Angeles, which included construction beside an existing hotel, streets, and surrounding structures. Three AMTS units monitored shoring and nearby structures; camera-equipped instruments and ALDs reduced the need for hazardous or disruptive access. Reflectorless measurements supplemented road prisms that were damaged by street-cleaning equipment. Nine wireless tiltmeters monitored structures in locations where cabling and conventional communications would have been difficult; a single gateway connected all sensors without repeaters.<br /><br />Monitoring data were transmitted to an online system, with alerts sent to project participants when engineer-defined thresholds were exceeded. The system helped identify excessive shoring movement and supported timely corrective action. The case study demonstrates that modern automated and wireless monitoring can reduce construction interference while improving access to data and monitoring continuity.

Keywords

deep excavations

geotechnical instrumentation

monitoring

automatic motorized total stations

automatic leveling devices

reflectorless measurements

wireless sensors

LoRa communication

tiltmeters

construction monitoring