Scope of Work:	GPR Investigation to map underground Void and track settlement up to depth of 6m.
Location:	Dakshineshwar metro station and Baranagar metro station, Kolkata.
Client:	RVNL.
Equipment:	GSSI SIR 4000 equipped with 200 MHz and 400 MHz center frequency antenna.
Challenges:	Machine movement at track area.
Summary:	Deterioration of any structure due to water intrusion can be a serious problem and can lead to compromise public safety with times. Surface defects like cracks and spalling can be identified by visual inspection techniques, but subsurface distress such as air voids and water voids inspection needs to be done using proper technique. Ground Penetrating Radar (GPR) in imaging buried objects at the worksite is seen as a helpful tool in providing detailed information that could be used for such identification. This project includes an investigation of metro tracks and embankments to detect any kind of voids, discrepancies that may lead to track settlement. Therefore, a GPR survey has been carried out at two different metro locations (near Dakshineshwar metro station and Baranagar metro station) in Kolkata, West Bengal to inspect the existing metro route. The scope of work includes the scanning of metro route and Embankment, at each location to find voids, settlement issues, and other discrepancies. The expected depth of penetration during the survey is up to 6 m. The survey has been executed using 200 MHz and 400 MHz center frequency antennas mounted with GSSI SIR 4000 GPR systems.