26.12.11

Kolkata Metro snippets

The New Year is all set to infuse a fresh lease of life into the East-West Metro project. Work on the underground section of the Metro, which will run from Salt Lake to Howrah Maidan and back, will finally begin in January. A major part — from Subhas Sarobar to Howrah Maidan — of the Metro corridor will be underground and significantly, it will also run below the Ganga river bed. Tunnel boring machine (TBM) will be used for implementation of the underground transportation system. In fact, this is the first time this mechanism will be used in this part of the country. While the 5.77-km stretch from Sector V to Salt Lake Stadium would be over ground, the TBM will be lowered at Subhas Sarobar from where an 8-km tunnel will be bored till Subhas Sarobar. Another TBM will be lowered at Howrah Maidan to move below Howrah Station complex and the river bed. It would continue to BBD Bag via Brabourne Road, and then to Bowbazar via BB Ganguly Street to Sealdah. From Sealdah, the tunnel will move further to Phoolbagan via Narkeldanga Main Road. Near Swabhumi at Subhas Sarovar, the Metro will come onto surface and it will move along the elevated track on Eastern Metropolitan Bypass. It will then run to Central Park Bikash Bhawan, Karunamoyee and terminate at Salt Lake Sector V. It is expected that commuters won’t have to go through the nightmarish experience they suffered during the construction of the north-south corridor. There would be hardly any trouble on the surface while work on the underground portion is underway. Tunnel boring machines ensure there’s no trouble on the surface. Traffic on the surface would not be disturbed, claimed a senior Kolkata Metro Rail Corporation (KMRC) official. However, the official conceded that construction of the tunnel, especially the stretch below the river bed, is going to be a technological challenge. In case of the East-West Metro corridor, the soil will initially be dumped at Howrah Maidan. Later, it will be transported to fill up the low-lying areas of Rajarhat Township. Depending on rock strata and tunnel requirement, the tunnel will be cased or lined. The precast concrete sections will be jacked into places as the TBM moves forward. In case of East-West Metro, the diameter of each tunnel will be 5.2 meter (internal). The stations will be around 13 meter below the road surface. However, KMRC will construct the elevated portion (5.77 km) first since this portion will be constructed mainly on government land, said another engineer.

No comments: