As it is clear that non of three mentioned stations are not in CENTER of city but like SDAH KOAA is also close to CBD of Kolkata. Regarding connectivity or taxi services when more train services starts from here naturally allied services will follow.
Regarding Metro we all know the pain of HWH where no such service exists.
So premium trains can starts from there and more city buses can be started from there for better connectivity.

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KOAA is not in centre of the city, but the main reason people tend to avoid it is that the station is not over the main road. One has to travel about a km inside to reach. But in centre of Kolkata there is no space to build more stations and HWH, SDAH cannot be expanded. so the new ones are going to come up at far flung areas. That way SRC is doing great job as it has good connectivity. All other cities are going that way only.

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For starters Poorva can be shifted here. It is an extremely popular trains as it is one of the best to reach Delhi(we know about the rush in trains between HWH-NDLS). Also, Poorva is going to have only 1 general coach so there will be less UR pax.

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Crossing HWH bridge is no issue at all ?

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