Tunnelling in challenging topography and geological conditions for a railway doubling project in Eastern Ghats, India

East Coast Railway is constructing a new railway line parallel to an existing one in Koraput- Singapur Road section. This 164 km long railway line has 36 existing tunnels and 24 tunnels for proposed second line. The existing line was constructed in 1982 through a dense forest and varying geology. This paper focuses on a smaller section of 45 km length between Tikri and Bhalumaska with 19 proposed tunnels. The existing railway line passes through steep gradient with sharp curves. This region has low population and has dense forests. Proposed line is planned to increase capacity of section. Planning optimised alignment was a challenge with range of factors affecting the decision. The project encountered geological challenges during design of proposed Tunnel 23. Various failures were recorded while existing Tunnel 23 was constructed. The challenges faced during execution of project and how decisions were made while following sustainable practices are discussed.