Work on a metro project in Kolkata has been halted again after further unknown piles were discovered, The Times of India has reported.
Plans for the tunnelling on the east-west section of the Kolkata Metro in India, have been delayed again after eight unknown piles were discovered.
This latest find was discovered whilst tunneling to remove the earlier unknown steel H-piles that once supported a temporary iron road for the construction of an existing station in the 1980s discovered earlier this year and were found to be obstructing the path of the TBMs.
Kolkata Metro Rail Corporation (KMRC) will now dig two extra branch tunnels to remove the steel piles before the TBMs can start boring the tunnel between Esplanade and Sealdah.
The Times of India has reported that the micro-tunnelling the firm used the new Austrian tunnelling method (NATM) for removing the piles. Around 80m of micro-tunnelling was completed in the last two months to reach 8m below the north -south metro tracks and remove the joists.
Two more piles were found after 20m of micro-tunnelling and ITDITD Cementation, the firm contracted to build the East-West tunnels, has removed them en route.
The paper said that the contractors were now waiting for permission from KMRC to build the branch tunnels - 13m east and 12m west - and it is hoped the extra 25m of tunneling will be completed by mid-January, so the TBMs can start boring.
A source told the paper: “The branch tunnels would mean extra work for the contractors. They would take some time to dig two more branches (13m and 12m) on either sides of the micro-tunnel around 30m from the point where it starts. It’s a complex job, and slightly time-taking.”
It is planned for the metro to be open by June 2021.