PM Modi inaugurates Underwater Metro: Prime Minister Narendra Modi inaugurated the country’s first underwater metro in Kolkata on Wednesday. This metro will run on a track built 33 meters below the ground and 13 meters below the level of the Hooghly River. In 1984, the country’s first metro train ran in the Kolkata North-South Corridor (Blue Line). After 40 years, the country’s first underwater metro rail will once again run from here.
For this, a 520 meter long tunnel has been built from Howrah station to Mahakaran station, in which two tracks have been laid. The metro train will cross this tunnel in just 45 seconds at a speed of 80 km/hour. This will improve the connectivity of Howrah and Kolkata. Travel of 7 to 10 lakh people every day will be easier.
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The deepest metro in the world, it has 4 underground stations
Some underwater metro routes are part of the East-West Corridor (Green Line). Of these, 4.8 km route from Howrah Maidan to Esplanade is ready. It has 4 underground stations – Howrah Maidan, Howrah Station, Mahakaran and Esplanade. Howrah station is built 30 meters below the ground. This is the deepest metro station in the world. Currently, underwater metro routes are built only in London and Paris.
The boring machines were named after the daughters of company employees
The boring machines were named after the daughters of company employees by
Syed Mohd., Director (Project and Planning), Kolkata Metro Rail Corporation. Jamil Hasan says that in 2010, the contract to build the tunnel was given to Afcons company. Afcons procured Tunnel Boring Machines (TBM) from German company Herrenknecht. The machines are named Prerna and Rachna, after the daughters of an AFCON employee.
Two biggest challenges of this project
The two biggest challenges of this project were 5-6 months spent in soil survey itself . First, selection of right soil for digging and second, safety of TBM. In Kolkata, different types of soil are found every 50 meters. 5-6 months were spent in soil survey to identify the right place for the tunnel. Then, after 3 to 4 surveys, it was decided that a tunnel could be built in the soil 13 meters below the bed of Hooghly river near Howrah Bridge.
The work of making tunnel under water was started in 2017
After realignment, TBM started making tunnel under water in 2017. The excavation work of the tunnel under Hooghly was to be completed in 125 days, but it was completed in 67 days. On September 1, 2019, TBM Chandi was about half a kilometer away from Sealdah when it collided with a big stone.
Due to this, the tunnel was filled with soil on a large scale and many buildings of Bahu Bazar were damaged. This incident shook everyone. Hundreds of families had to be shifted to hotels. The High Court stopped the work. When there was no subsidence for a few months, work started again in February 2020.
