First TBM at Mumbai Metro 3 successfully launched

December 04, 2017: After months of geotechnical investigations, planning and a lengthy procurement phase, HCC Metro Project Line 3 Pkg 2 team successfully launched the first of the two TBMs from the project site at Chhatrapati Shivaji Terminus in Mumbai on December 04, 2017. This event was graced by the presence of Mrs. Ashwini Bhide, Managing Director, Mumbai Metro Rail Corporation and senior bureaucrats from State and Central Government, BMC and MMRCL.

The TBM is expected to record an average drilling rate of around 13 meters per day over the course of its 4.049 km drive from Chhatrapati Shivaji Terminus to Mumbai Central via the station boxes at Chhatrapati Shivaji Terminus, Kalbadevi, Girgaon and Grant Road.

The launch of TBM is a complex process and is done in 3 sections over a period of 7 to 8 weeks. The first phase is Initial Drive during which the Cutter Head, Shield Body and the Tail Shield body are lowered in the launch shaft. These three sections of around 20 meters are then joined together. The cutter head starts drilling and simultaneously moves in the rock body. During this drive, the TBM moves on a narrow gauge rail line.

The second phase is Transfer Drive during which the back-up gantries are lowered in the launch shaft. Then these gantries are pulled in the tunnel created by the cutter head and connected with it. A broad gauge rail line is required in this phase because the gantries are bigger in size and the locomotive used for the transportation of muck needs to fit in the gantries. The last and final phase is Main Drive, during this the rest of the parts are lowered and connected. In this phase, the TBM is ready to be fully operational.

The initial drive for the first TBM launched was completed on January 11, 2018 and the Main Drive started in the 2nd week of February 2018. This TBM requires around 32 people to operate, which includes TBM operators, engineers and labours. Terratec, the manufactures of the TBM will provide support to the TBM Team for initial 6 months or 150 meters length drilling.

The first Tunnel Boring Machines (TBMs) being used at the Mumbai Metro Project Line 3 Pkg 2 had arrived at the site location in September 2017 and the second one arrived in December 2017. Manufactured in China, these TBM’s are Single Shield dual-mode hard rock TBM. They are equipped to operate in both, open or closed mode, in the predominantly fresh and slightly to moderately weathered Basalt and Breccia that are anticipated in the Mumbai Metro project.

After arrival at Mumbai Port, transportation of the TBM from the BPT Orange gate to the project site at CST was a dunting task. Due to the enormous size of the TBM, the entire process of transportation was thoroughly planned to take into consideration every single obstacle on the way for the smooth movement. Despite challenges, the project team carried out the entire operation with utmost precision.