The latest accident in Bowbazar triggered by East-West Metro tunneling work has again cast a cloud of uncertainty on the project, which will link Sector V and Howrah Maidan.
Officials of the Kolkata Metro Rail Corporation (KMRC), the implementing agency of the project, said experts from Delhi and Bangalore Metro were expected in Bowbazar in a week. They will inspect the tunnel and give a detailed opinion.
“We are in talks with experts from Delhi Metro and Bangalore Metro. They are expected in Kolkata by next week. Till then, tunneling work is on hold,” C.N. Jha, managing director of the KMRC, said on Sunday.
But even after a nod from the team of experts, the KMRC will have to inform the police and the civic body more than a week before the start of any underground work in Bowbazar.
Cracks appeared in around a dozen houses in the Bowbazar area following water seepage during construction of a passage to connect the two tunnels of East-West Metro on Friday. The seepage of water has been arrested but all underground work has been put on a hold, said officials.
“We have stopped the water ingress. But we have to keep the affected area under observation for at least a week. The remaining tunneling work is on hold. Any progress will happen after a feedback from experts from Delhi and Bangalore,” said an engineer of the KMRC.
Eight cross passages (the ones linking the two tunnels) are part of the underground design on the stretch between Sealdah and Esplanade. Three of them are complete and construction of the fourth led to Friday’s disaster.
Two of the remaining cross passages will be connected to a ventilation shaft that is being built at Subodh Mullick Square. Sources in the agency said that under the changed circumstances, there was a possibility that work on the affected passage would be suspended for now and construction of the two passages that will be linked to the ventilation shaft will start.
But after three similar accidents in the past three years, the KMRC is sceptical about going ahead without a validation from external experts.
On May 11, excavation of soil under the Howrah-bound tunnel led to leakage of water, which in turn caused subsidence and cracks in several buildings.
The accident happened during the construction of a concrete structure to fill a yawning gap — in the form of a retrieval shaft between the two tunnels. The shaft was 38m in length and construction of 29 metres had been completed when the accident occurred. “There was a lot of soil loss around the structure during the May accident. The external loss has been compensated by grouting. Now, the concrete casting of the remaining 9 metres can start. There is a common access point for the construction of the retrieval shaft and construction of the cross passages in the ventilation shaft. Both sets of work can go on simultaneously once we get a go-ahead. But nobody seems to know when the nod will come,” said another KMRC official.
On Saturday, Kolkata mayor Firhad Hakim said KMRC had been asked to inform Kolkata Municipal Corporation “maybe 10, 15 or 20 days” before starting any tunneling work in Bowbazar so that residents could be shifted in advance.
On Sunday, a KMC official told The Telegraph that the KMRC did not need the civic body’s permission to resume work. A meeting at Nabanna on Saturday decided that the KMRC would inform the state government before starting work so that people could be shifted as a precautionary measure.
“KMRC officials had proposed that, henceforth, people should be evacuated before work in an area begins, instead of asking people to leave within minutes if cracks develop,” said the official.
Before the May 11 accident, the target for the completion of East-West Metro was January 2023. The May accident pushed the target back by around a year, according to KMRC officials. No one was willing to comment on the possible delay because of the latest accident.
Work on the Howrah Maidan and Mahakaran stretches will go ahead, said officials.