Surprise attacks by enemy troops hiding in tunnels are difficult to predict, although radar technology can help by finding the tunnels. The Rapid Reaction Tunnel Detection (R2TD) system can detect the underground void created by a tunnel, as well as electrical cables or devices within the tunnels, using ground-penetrating-radar (GPR) technology.
The system was developed by engineers several years ago at the Geotechnical and Structural Laboratory of the U.S. Army Engineer Research and Development Center (Vicksburg, Miss.) It employs sensors to detect acoustic and seismic energy. The R2TD system can be mounted in a vehicle or carried by a soldier to an area of interest, and is capable of transmitting data to a remote post for data analysis.
The system has been in use since 2014 and typically requires only one day of training by combat engineers for fully effective operation and results. Because adversaries are continually adapting—using different tunnel depths and more complex maze configurations—the analysis software for the R2TD system must be continually refined, with increased transmit power for greater ground penetration.