The tender for construction of the Metro Rail corridor near the airport, the last in the series for Phase-I of the project, is likely to be awarded by this month-end.

Once the contract for the three-km stretch, extending into the airport, is finalised, work on the entire 45 km of the Metro Rail network, comprising 19 underground and 12 elevated stations, would have been “committed”.

The unique feature of the three-km corridor is a small 500 metre underground stretch that starts near the Trident Hotel on GST Road. Metro Rail Corridor-I (Washermenpet to Airport), which runs as an elevated section at a height of 12 metre from Little Mount, would at that point dip nine metres below the ground near the airport.

This is to present a clear skyline to the airport's secondary runway. The tracks of the Metro line will come above ground after crossing the plane approach area, making it resemble a rollercoaster, a senior Metro Rail official said.

He said that special provisions would have to be made for ventilation and other facilities. “There will also be a limit on operational frequency. The compromise had to be made due to air safety considerations.”

To overcome these difficulties, the Delhi Metro Airport Express line's approach to the T3 terminal is entirely underground. An elevated section was preferred in Chennai to bring down the cost.

Despite the change in alignment, the final height of the airport Metro station would be on the same level as the first floor of the new terminal that is being constructed.

K. Rajaraman, Managing Director, Chennai Metro Rail Limited, said that a tube from the station would directly lead to the proposed 900 metre walkalator on the first level of the new terminal.

The construction of two Metro Rail corridors was inaugurated in June 2009. The first corridor will run between Washermenpet and the airport along Anna Salai. About 14 km of this stretch will be below ground and 8.8 km elevated.

The second corridor is between Chennai Central and St.Thomas Mount and it would predominantly pass through Poonamallee High Road and Jawaharlal Nehru Salai.

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