Contractor Afcons Infrastructure has announced the breakthrough of its third tunnel boring machine (TBM) on the Chennai Metro project in India.
The 6.65m diameter Robbins earth pressure balance TBM had already completed two tunnel drives on the project.
According to Afcons senior manager Gopal Dey, the project called for a TBM that was specially tailored to the ground conditions on the project which were expected to vary from soft clay to mixed ground with rock. “The Robbins EPB TBMs have unique design features that optimise the machine for the geology,” he said.
Robbins has said that the reuse of a single TBM for multiple drives is a growing trend. The TBM used for the Chennai scheme was refurbished on site after the first two drives before starting on the 1.8km tunnel in February which it has just completed. This latest tunnel connects multiple stations along the metro line, starting from Washermenpet through to Sir Theagaraya and to Kurukpet.