Design and Construction of Bored Tunnels for Mumbai Metro Line 3

This paper discusses the challenges in design and construction of the complete underground Mumbai Metro Line 3 in the city centre of Mumbai, which is the fi nancial capital of India and home to about 22 million people. The Mumbai Metro Line 3, which is a 33.5 kilometre fully underground corridor, is presently under construction. The project scope includes 33.5 kilometre of twin tube tunnelling by tunnel boring machines (TBM). The hydrogeological conditions of Mumbai, challenges posed by tunnelling under existing buildings and its impact on choice of TBM types adopted in the project are described. The design approval process for TBM selection and design features of each TBM type are discussed.