Calcutta: The defence ministry has ended the stand-off that had prevented the Joka-Esplanade Metro corridor from having entry and exit points overground for two proposed underground stations on the Maidan side.

The army, which is the custodian of the Maidan, had refused permission to Metro Railway to create passages through which commuters could enter and exit the underground Victoria Memorial and Park Street stations on this new route.

After years of resistance to the construction plan, the defence ministry recently gave the green signal to start construction with some modifications to the plan.

A senior railway official said both stations under the Maidan would have two gates each for entry and exit instead of the usual four. "This is in line with the army's request for minimum possible construction overground."

According to the official, the existing Park Street station for the north-south route has provision for another pair of tracks along the platform on the Maidan side.

"This will create a common corridor for commuters to switch from one line to the other after the Joka-Esplanade route becomes operational," he said.

The breakthrough came after multiple meetings initiated by the state government. Metro Railway has written to its Delhi headquarters to allocate funds so that construction can start as quickly as possible. The state government has sent a similar request to the railway ministry.

The route will be an elevated one till Mominpore. The tracks will go underground for the next 6km, covering Kidderpore, Victoria Memorial, Park Street and Esplanade stations.

Surveys had been conducted by the railways, the state government and the army before the site for the Victoria Memorial station was fixed beside a fountain on the Maidan side. Park Street station will be adjacent to the existing one.

Mominpore station will have one level instead of two because of a height restriction at that site. Most Metro stations have a concourse for the ticket counters and offices.

In the original plan that had been drawn up in 2011, the route was supposed to be elevated throughout. The change was made on the army's insistence.

Railway officials said implementing the revised plan would entail an additional cost of Rs 2,300 crore. The original estimate for the 6km stretch was Rs 600 crore.

"We had convened several meetings to request the ministry of defence for clearance and they have finally given it. The onus is now on the railways to sanction the additional cost," a senior official of the state government said.

Sources in Metro Railway said the Railway Board was evaluating the revised cost estimate.

The defence ministry had agreed to allow tracks of the Joka-BBD Bag Metro to go through the Maidan in 2015, ending a four-year stalemate. This was after Prime Minister Narendra Modi asked the ministry to ensure that the project was not derailed.

Construction still did not start because the crucial decision on entry and exit points from the Park Street and Victoria Memorial stations remained to be taken.

Work on the 16km corridor had started in July 2011, but the project soon ran into land logjams. Rail Vikas Nigam Ltd, the implementing agency, has split the project into two phases. Construction is currently underway between Joka and Majherhat.