Chennai Metro Rail Limited (CMRL) commenced tunnelling using the first Tunnel Boring Machine (TBM) at Nehru Park metro station on Saturday.
Two TBMs shipped from Shanghai in China, in December last year, as a part of an MoU between CMRL and joint venture partners, Larsen & Toubro, India, and China-based Shanghai Urban Construction Group, have been assembled in the city.
The TBMs are used to excavate tunnels with circular cross section in order to connect underground stations. A total of 11 TBMs will be used for Metro Rail work in the city. Two of them will be deployed at Nehru Park station. Chinese workers who arrived in the city last month will handle these machines.
“Of the 11, we expect nine TBMs to be operational by year-end and the rest by the beginning of next year,” said Rock Mickell of General Consultants. The firm is assisting CMRL in supervising the metro rail project in the city.
With a capacity to work continuously for more than 10,000 hours, TBMs can operate at speeds varying between 6 metres to 10 metres per day.
The first tunnelling segment from Nehru Park station to Egmore station, a distance of 939 metres, will be covered in five months.
Heavy concrete liners for the tunnels were manufactured in a casting factory at Vayalanallur on the outskirts of the city.
An underground metro station consists of three levels — roof, concourse and base. The platform will be at base level. The stations will have multiple entry and exit points. Work on underground stations is expected to be completed by April 2015.
Phase 1 of the Metro Rail project comprises two corridors with a combined length of 45 km. Corridor-I runs from Washermenpet to airport via Anna Salai, and corridor-II connects Chennai Central to St. Thomas Mount via Koyambedu.
