Metro tunnel boring starts

Chennai: The fears of George Town, Chintadripet and Shenoy Nagar residents have been proved groundless. The TBMs (tunnel-boring ma­chines) of Chennai Metro Rail (CMRL) are roaring beneath their houses without their even feeling it.
Senior CMRL officials, who confirmed that boring work was under progress in these areas, told Deccan Chronicle that the mach­ines have dug nearly 400 metres in Washer­manpet area alone. The first TBM has dredged over 280 rings (each ring measuring 1.4 metres) and the second machine has tunnelled 93 metres in Washermanpet.
The two TBMs in Nehru Park, from where the first TBM of CMRL set rolling, has dredged 283 rings and 135 rings (1.2 metres) respectively. May Day Park, where dredging beg­an most recently, has cove­r­ed 16 rings (each 1.5 metres). Five of the 11 TBMs shipped from abroad for the underground sector are in motion.
Of the 24 km underground stretch of the entire 45 km metro rail network, TBMs would run beneath 240 stru­ctures in Mannadi, 110 in Chintadripet and 53 in Shenoy Nagar, an official added.
However, tunnel boring ran into trouble at Seven Wells last week when concrete poured from overgro­und for metro work seeped into a borewell falling within its route, littering the interior of a nearby shop. Bla­ming the shop-owner for failing to inform them abo­ut the presence of the bore­well, CMRL officials said, if informed, the bore­well could have been closed like others and necessary compensation paid to him. In this case, the shop-owner was not aware of a borewell in his shop. CMRL identified and closed 397 bor­ewells and 57 open wells fall­ing within its route.
There was no reason to fear as tunneling takes place 9 metres beneath the surface, officials reasoned, adding that protective girders and diaphragm walls would keep the tunnel in tact. Also, the TBMs are fully automated and the machine adjusts speed by factoring in the soil nature.