The East-West Metro that was cleared by Delhi last week will be a unique project even for a city that has had an underground rail link for 24 years. Metro presents an FAQ to put doubts, if any, to rest.

What is East-West Metro?

Although modelled on Delhi’s Metro Railway, the East-West project will be the first in the country to have an underwater section. The stainless steel rakes will be almost noiseless, lighter, spacious and more comfortable than those that ferry people on the Tollygunge-Dum Dum route. Work on the Rs 4,676-crore project will start in January and the first phase is likely to be inaugurated by 2014.

The state will bear 30 per cent of the cost and the Centre 25 per cent. The remaining 45 per cent will be a soft loan from the Japan Bank for International Cooperation.

Which places will it connect?

It will connect Sector V in Salt Lake with Howrah, a distance of 13.77 km. There will be 12 stations, six above the ground and as many underneath. The surface stations will stand atop concrete pillars around 12 metres high.

Which portion will be under the Hooghly?

The underwater stretch will be around eight km, from Howrah to Subhas Sarobar. A joint venture company, Calcutta Metro Railway Corporation, will be in charge of the project. It will appoint a consortium of general consultants — to be selected through a global bidding process — to execute the project.

What kind of technology will be used?

The stretch underneath the Hooghly will be created with a massive tunnel-boring machine. The plan is to dig a tunnel 30 metres below the riverbed, through which the tracks will be laid. The tracks will be of standard gauge, instead of broad gauge. From Subhas Sarobar, the tracks will be elevated.

Will it be safe under water?

Londoners have been passing through the Thames tunnel for over a century.

The use of a tunnel-boring machine instead of the drilling and blasting method will ensure that the East-West Metro tunnel is created without disturbing the surrounding soil and, therefore, avoiding subsidence. Experts say that nobody will be able to make out they are travelling through an underwater tunnel and that no structure built on the surface will be under threat.

The stations of the tracks underneath will have entrances on the ground, just like the Metro stations between Tollygunge and Dum Dum.

How much digging is involved?

There won’t be too much activity — or chaos — at ground level because half the project will be underground. The concrete pillars on which the elevated portion is to stand will be built on the median dividers to avoid traffic disruption. The only problem, if any, will be constructing the stations.

At which point will the two Metros meet?

East-West will meet the North-South corridor at Central station. Passengers using the North-South Metro can walk a tier below and get a link to the East-West Metro. “The architects who designed Central station had left a provision for such connectivity,” an official said.

How much time will it take from one end to the other?

Between 35 and 40 minutes.