The viability of the much-anticipated Joka-BBD Bag Metro corridor will be jeopardised if Kidderpore station does not come up, said railway officials.

Residents of Kidderpore and surrounding areas like Garden Reach and Metiabruz — the slice of Calcutta has thriving trade hubs, a cluster of hospitals, schools and colleges — will also miss out on fast and reliable urban commute, they said.

Metro reported on Sunday that the proposed Kidderpore station has been all but scrapped because of the state government’s alleged refusal to permit construction inside the Kolkata Armed Police compound at Alipore’s Bodyguard Lines.

Officials of Metro Railway and the RVNL, the executing agency of the Purple Line, have said major design tweaks will be needed to bypass Kidderpore, which was projected to be one of the busiest stations in the corridor.

“For people like us, the nearest Metro station now is Hazra (Jatin Das Park). We have to take an auto or a bus to get there. A Metro station in Kidderpore would have made daily travel much more comfortable. We are still hopeful that some solution will be worked out,” said Syed Moin, a business consultant who lives in Metiabruz and has to travel across the city.

The Purple Line, once ready, will meet the Blue Line (north-south corridor) and Green Line (East-West Metro) at Esplanade.

Connectivity will not be the only loss if the Kidderpore station does not happen.

Design tweak

The distance between two Metro stations is usually around 1km to 1.5km, said railway officials.

If Kidderpore station is skipped, trains will stop at Victoria after Mominpore. The two are 3.2km apart.

“The tunnel ventilation shaft has to be relocated. It has to come up between Mominpore and Victoria. The cost to build a tunnel ventilation shaft is more than building a station. It was supposed to have come up near Kidderpore. Now, it will have to be redesigned,” said an RVNL official.

The tweak will push back an already much-delayed project, said RVNL sources.

Train frequency

Bypassing Kidderpore station will also put curbs on the frequency between two trains, said Metro officials.

The average speed of a Metro train is around 34kmph. Operational guidelines say there should not be more than one train between two underground stations.

A train will take around six minutes to reach Victoria from Mominpore and vice versa. That means the interval between two trains cannot be less than six minutes,” said the official.

Power worry

The official also flagged the risk of a train getting stranded.

“If there is a outage in a substation in Victoria and a train gets stranded in the tunnel, it will be a Herculean task to get it moving because then, the distance between two substations (at Park Street — the station after Victoria — and Mominpore) will be more than 5km,” he said.

A substation receives power from the CESC before feeding it to the Metro stations.

Tunnel work

The Purple Line is now functional on an 8km elevated stretch between Joka and Majerhat. The next stop, Mominpore, will be the last elevated station, and Kidderpore was supposed to have been the first underground station.

While Kidderpore station is uncertain, construction of the Metro tunnel from Majerhat to Maidan is underway.

The shaft to launch the tunnel boring machines (TBM), inside the St Thomas’ Boys’ School is ready.

The first of two tunnel boring machines arrived in Calcutta in April from Germany via Tamil Nadu. A second TBM reached the city last month.

Parts of the first TBM have already been lowered into the shaft. The parts will be assembled in the shaft, and the machine is expected to start boring from July, said an engineer.