The plan to link Metro Railway to the airport and further north to Barasat is back on track after six months of uncertainty with the authorities deciding to stretch the underground tracks a bit to ensure safety of flights.

Two Metro projects worth around Rs 7,000 crore — Dum Dum-airport-Barasat and New Garia-airport, via Rajarhat — hit a wall around six months ago after the airport authorities complained that the elevated tracks linking the North 24-Parganas town would come in the way of flights.

“We have decided to change the level of the tracks to address the concern of the airport authorities. The revised plan will soon be discussed by representatives of the railway board and the civil aviation ministry,” a Metro official said on Sunday.

According to the altered plan, the Dum Dum-airport-Barasat link on an elevated corridor will end at Biman Bandar station of the suburban network.

The line from New Garia (Kavi Subhash), which will go underground near City Centre 2 in Rajarhat, will extend till Barasat after emerging overground beyond the Belghoria Expressway-Jessore Road crossing.

“In the initial plan, the tracks from New Garia were to run underground around 3km from City Centre 2 till the airport. In the new plan, they will run another 700 metres underground and then around 8 km on an elevated corridor from the Jessore Road-Belghoria Expressway intersection to Barasat,” the official pointed out.

Part of the Rs 2,900 crore allotted for the originally planned 18km link between Dum Dum and Barasat will be spent on laying the tracks for stretching the New Garia line till Barasat.

The airport authorities, which had objected to the Dum Dum-Barasat project, said they would give their nod to the new plan if the tracks did not obstruct flights. “If there is no obstacle in the flight path, there should not be any problem. Finer points, such as location of the station and the alignment of the tracks on the airport premises, can be worked our after we study the plan in detail,” an official of the Airports Authority of India told Metro over the phone from Delhi.

Metro officials said they would have incurred an extra cost of Rs 550 crore if the Dum Dum-airport line had to be taken underground. “We will use the elevated tracks of Eastern Railway to run Metro trains from Dum Dum to the airport. The only change required is replacing the overhead power supply with the third rail system used in Metro,” the official pointed out.

Metro sources said the tendering process for parts of both projects could not be started because of the uncertainty. In the Dum Dum-airport-Barasat project, work could only be started between Barasat and Hridaypur and between Dum Dum and Dum Dum Cantonment.

For the New Garia-airport link, a Rs 3,951crore project, tendering has being done for 25 of the 32 km.

The twin projects are running late by a year, the original deadline for both being the 2014-15 fiscal. “If the revised plan is approved immediately, work could wrap up by 2015-16,” said the official.