Tunnel boring machines that will build the underground network of metro rail’s phase-2 construction are getting ready to arrive in the city even as one of the first machines for the project completes factory tests. Tata Projects Limited, which will build an underground section in the project, recently confirmed through an online post that it has successfully completed the factory assurance test for the first tunnel boring machine for the Chennai Metro Rail Project. The 118. 9km phase-2 project, which is expected to be completed by 2025, has a 42. 6km underground network with 48 sta tions. “We are particular that new tunnel boring machines are deployed,” a metro rail official said.
Officials said the TBM which completed factory tests is an earth pressure balance machine where the cutters in the cutter head on the front of the machine rotate and drill through the soil applying force and pressure. It injects foam to soften the earth for drilling. The machine then holds up a few feet of earth in front of its face by applying pressure before boring further and moving forward. Officials said a total of 23 machines will operate in tandem in various locations complete tunnel construction faster. The 45. 8km corridor-3 may have 15 TBMs, 26. 1km corridor 4 and 47km corridor-5 may have around four machines each.
