BENGALURU: The first indigenously assembled tunnel boring machine (TBM) of Namma Metro began burrowing through the soil beneath the Rashtriya Military School towards Langford Town on Friday. This marks the first step taken towards completing the 650-metre stretch that it would drill over many months.
The TBM, operated by AFCONS Infrastructure Limited, made its first move 60 feet beneath the ground at 9.30 am. This is the fourth TBM that has begun drilling for the 13.92-km underground network between Nagawara and Diary Circle.
Speaking to TNIE, a source said, “The TBM, which is yet to be christened, covered only a miniscule distance on Friday. The crucial development is that tunnelling has begun. There are 60 people operating the machine. It will drill for till 650 metres, after which it will be dismantled and lifted to the ground level and transported by road again to the Military School. The parts will have to be lowered again to begin work from the same spot for the second tunnel.”
It has taken 37 days since the first part of the machine was lowered to facilitate the drilling. “On February 4, the ‘middle part’ of the machine was sent below using a special 700-tonne gantry crane, an equipment used by the BMRCL for the first time. Later, the cutter head and the tail were lowered and the machine was assembled as one.
The machine’s parts were manufactured in Germany by TBM maker Herrenknecht, imported to Chennai, assembled there and transported via road to Bengaluru. This is the fifth TBM of BMRCL that has been lowered 60 feet below and the fourth to begin tunnelling. The UG corridor has been divided into four packages and the drilling launched on Friday is referred to as the ‘first package’, the source said.
TBM Avni is drilling from Shivajinagar to MG Road and has completed 300 metres. TBM Lavi, that is supposed to drill along the same direction is on the verge of commencing drilling. TBM Urja, drilling from Cantonment to Shivajinagar, has completed 375 metres, while TBM Vindhya, which began in the same direction has has covered 288 metres.