<h1>Underground railway tracks planned along 40-km strategic corridor to strengthen connectivity and security, including conversion to six-track corridor.</h1> Plans propose constructing underground railway tracks along a 40-km strategic corridor between Tin Mile Haat and Rangapani, laid about 20-24 metres underground, to address security and air-defence connectivity needs. Simultaneously the existing double line on the stretch will be converted to a four-line surface configuration, resulting in a six-line corridor composed of four overground and two underground tracks.