ABSTRACT
Urban Metro Tunneling in Mumbai has recently witnessed a positive breakthrough in last few years and Mumbai Metro Line-3 is one such project planned fully underground from Colaba to Seepz and in construction stage. Tunnel construction in the financial capital of India has its own unique set of challenges including presence of shallow groundwater table, sound bed rock, presence of heritage buildings, some of them are severely dilapidated, with heavy traffic movements on roads. This study is based on the case of Hutatma Chowk station of the Mumbai Metro Line-3 project, where it was proposed to construct a part of the station below the road and one platform tunnel of 253 m long, 9.7 m height, 11.78 m wide below heritage buildings by conventional tunneling due to topographical constraints. A rock pillar of only 3 m was available between the east side wall of the station box and the platform tunnel. Legal and regulatory circumstances led to a situation where the TBM would have been on hold for about 26 months having cascading effects on linear activities. This study analyses the challenges faced leading to an innovative and unorthodox solution and sequence of works resulting in minimum impacts on construction schedule.
