The Brihanmumbai Municipal Corporation (BMC) on Wednesday began lowering spare parts of a Tunnel Boring Machine (TBM) into the launching shaft for the twin tunnels being constructed under Phase 3-B of the Goregaon-Mulund Link Road (GMLR) project.
BMC Commissioner Bhushan Gagrani on Wednesday visited the site in the Dadasaheb Phalke Chitranagari area and inspected the process. Officials, while briefing about the ongoing work, said that the work has commenced nearly three months ahead of schedule, which is expected to accelerate progress on the major infrastructure project.
The 12.20-km Goregaon-Mulund Link Road aims to connect Mumbai’s western and eastern suburbs. As part of the project, twin underground tunnels will be constructed from Film City in Goregaon to Khindipada in Mulund. Each of the parallel tunnels will be about 4.70 km long and will feature three traffic lanes.
The tunnels will pass completely underground beneath the hills of the Sanjay Gandhi National Park, with tunnel diameters of 14.20 metres and 13 metres within the sanctuary area. Officials said the tunnels will be equipped with modern ventilation systems, fire protection mechanisms, drainage channels and dedicated utility corridors.
As per the official statement from the BMC, two tunnel boring machines, S-118 and S-119, will be used for the excavation. The machines have been built by Terratech, with a diameter of 14.49 metres and weighing around 2,175 metric tonnes each, making them the largest TBMs deployed in Mumbai so far.
First phase of launching the shaft completed
According to a statement issued by BMC, the first phase of the launching shaft at the Film City site has already been completed. The shaft measures around 200 metres in length, 50 metres in width and 30 metres in depth.
A specially designed concrete cradle measuring 20 m x 20 m x 2.5 m has also been constructed at the base to stabilise and correctly position the TBM during the launch.
From March 11, the process of lowering TBM components into the shaft began using high-capacity cranes of 800-tonne and 350-tonne capacities.
On the first day, the type ‘A’ shield, the main mining component weighing about 135 metric tonnes, was successfully lowered into the shaft.
Key components of the tunnelling system installed
Civic officials further said that several key components of the tunnelling system, including the main shield, cutter head, screw conveyor, main bearing and erector, have already been assembled and will be gradually lowered into the shaft before the final installation of the TBM. Once the machine is fully assembled, the actual tunnelling work will commence.
After the excavation from Film City through the national park area to Mulund’s Amar Nagar is completed, the TBM will be retrieved through a designated retrieval shaft at Mulund, where it will be dismantled.
