CHENNAI (Metro Rail News): In Chennai Phase 2 project a casting yard is being set up at Muttukadu along East Coast Road to cast ring segments for building metro rail tunnels to operate driverless trains across Chennai’s important areas.
According to the officials, the ring segments which are to be cast will go into tunnels on corridor-4 from Lighthouse to Power House in Kodambakkam and will cover around 10 km. Phase-2 tunnelling is expected to begin before the end of this year whereas the 118.9 km phase-2, including underground sections covering 48km, is expected to be operational by 2025-26 and a part of corridor-4 will open first by June 2025.
As per the officials, tunnels are being constructed by putting together precast concrete rings. The yard will cast approximately 9,000 ring segments which will go into the construction of the 10 km twin tunnels. Two stretches which are Lighthouse to Bharathidasan Road covering 5.15 km and 4.8 km Bharathidasan Road to Power House ramp with 10 stations and carry a four-year deadline.
According to the CMRL officials, tunnel boring machines will start arriving by August whereas the tunnelling is expected to begin in various locations by October end or the start of November. At least 23 tunnel boring machines will be operated across the phase-2 corridors for faster construction.
CMRL will use the ‘earth pressure balance’ method for tunnelling in which the cutters on the cutter head of the TMB rotate and drill through soil supplying force and pressure. It injects foam to soften the earth for drilling and then the machine holds up a few feet of earth in front of its face by applying pressure before moving forward.