CHENNAI: The Chennai Metro Rail Limited conducted the factory acceptance test for the second tunnel boring machine (TBM) that is to be used for the underground rail construction in corridor 4.

The second test of the machine, manufactured by German company Herrenknecht, was done in Tiruvallur in the presence of CMRL officials and consultants of the company. It would now be dismantled, packed and transported to Panagal Park station, T Nagar.

The 700-tonne TBM named S1075B has 6.670-metre bore diameter and 110-metre earth pressure balance machine.

The CMRL said the construction of the TBM launching shaft was under way at Panagal Park station and was expected to be ready to lower and assemble it in October. The machine will mine at a maximum depth of 26 metre below ground starting from Boat Club, to Nandanam, Panagal Park, Kodambakkam and finally reach the retrieval shaft after Kodambakkam flyover by September 2024.