CHENNAI: The Chennai Metro Rail Limited (CMRL) on Saturday held a factory acceptance test for its first tunnel boring machine (TBM) for underground sections in corridor 4.

For the underground (UG) project in corridor 4 (Light House station at Marina Beach to Kodambakkam flyover), construction has picked up pace. It’s split into two packages – (UG-01 and UG-02) with 4 km twin tunnels in each.

For completing the 16 km tunnelling work, four TBMs will be employed, considering both the upline and downline tunnels. The TBMs manufactured by a German company Herrenknecht are being used by CMRL’s contractor ITD Cementation India.

On Saturday, the factory acceptance test of TBMs, which is the first for UG-02 package, was done at the HK factory in Tiruvallur. The TBM has been named S1074B – a 6.670 M bore diametre and 110 m long earth pressure balance machine.

As per the CMRL press note, it weighs around 700 MT which will be dismantled in parts, packed and transported to its destination at Panagal Park station, T Nagar.

The construction of the TBM launching shaft, which is a part of x-over structure, is under progress at Panagal Park station and is expected to be ready to lower and assemble the TBM in October. This TBM will be launched in the downline of this corridor 4 and will mine at a maximum depth of 29 m below ground level starting from Panagal Park through Nandanam and finally scheduled to arrive at Boat Club by September 2024.