Underground drilling for East-West Metro corridor tunnel to

Undergpound drilling for a tunnel of the East-West Metro corridor project would get delayed by over a year, after a boring machine operating in Bowbazar area hit a water table and stopped functioning, a senior official said on Tuesday.

At least five houses collapsed owing to ground settlement from seepage during tunnel-boring work on Sunday, the Kolkata Metro Railway Corporation (KMRC) has said.

"It's delayed... It could be one year or little more than a year because of the (congested) area. Our target (to complete the entire East-West Metro) is 2021... We had a deadline to complete this tunnel work by December...," KMRC Managing Director Manas Sarkar said.

Sarkar was speaking to reporters following a meeting with Chief Minister Mamata Banerjee at the state secretariat.

"At the moment, our only intention is to contain the damage as much as possible... Retrieving this (tunnel-boring) machine will be extremely difficult as this is a very congested area," he said.

The portion of a building collapsed in the congested Bowbazar area in the central business district of the city, while several others subsided or developed cracks during tunnel boring work for the metro project on Sunday.

The building collapsed entirely on Tuesday.

Tunnels have been bored under the Hooghly river to connect the twin cities of Kolkata and Howrah through the rapid transit system, spanning a length of 16.6 km from Howrah Maidan to IT hub Sector V in Salt Lake.

The new metro corridor passes through some of Kolkata's most-congested areas where there are many century- old buildings.