Construction of Crossover at Acharya Atrey Chowk using TBM and NATM Technology on Mumbai Metro Line -3

Mumbai Metro Rail Corporation Ltd is implementing prestigious Mumbai Metro Line 3 project (Colaba-Bandra-SEEPZ) which is a completely underground corridor. Package 03 of Mumbai Metro Line 3 includes Construction of Five Underground stations between Mumbai Central to Worli and Associated Tunnels. The city of Mumbai was formed by merging of seven islands through multiple land reclamations. Mumbai geology consists of soft ground followed by volcanic rocks such as Basalt, Breccia, Tuff and intertrappean sedimentary rocks such as Shale. This paper describes challenges of NATM tunnelling under mixed ground conditions below E Moses Road, close to Acharya Atrey Chowk Station. The progress during NATM tunnelling is analyzed as per Mumbai geology. The paper illustrates the challenges encountered in deciding the location of Crossover as well as during the execution. It also highlights benefits of observational method in deciding the support class and how it helped to achieve required progress within given cost and resources.