Major upgrade planned for Blue Line’s ventilation and cooling systems

The city’s lifeline transport system which is also the country’s first underground Metro railway network is all set for a major revamp soon.

Kolkata Metro Railway’s Blue Line is to undergo an intensive upgrade of the ventilation and cooling system of stations and the tunnels.

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The Blue Line corridor is headed for a major upgrade in the next three to four years. The ultimate aim of the Metro authorities is to achieve the goal of 90 sec with which London and Moscow Metro are operating at present. However, before this upgrade of the north-south network, a major overhaul of various aspects is required, according to a senior official of the city Metro. To reach the goal, one of the major steps would be the update of the signalling system into ‘communications-based train control (CBTC), which is a railway signalling system that uses two-way radio communication between trains and trackside equipment to manage traffic and infrastructure.

But even for going into the CBTC technology that has been already sanctioned for this corridor, the civil engineering upgrade would have to be done. According to the city Metro office, as a part of this initiative, the power supply system, traction sub-stations, tunnel ventilation system, environment control system commonly known as air-conditioning system, signaling system, third rail system, rail track system are slated for improvement very soon under the ‘umbrella works that has already been sanctioned by the railway ministry to prepare the Blue Line for the ambitious project to achieve the ultimate goal of 90 seconds.

As a part of the overall improvement, the metro authorities are now working on plans to upgrade ventilation and cooling systems of stations as well as tunnels. In the 41-year-old existing system, tunnels were also cooled as the rakes were non-air conditioned. But as Metro Railway, Kolkata is now equipped with an AC rake fleet that provides the provisions to shift to the tunnel ventilation system to have state-of-the-art smoke extraction system as well. In the present system, forced ventilation using centrifugal fans of 110 kW at fourteen midpoints are being used. These fans rotate 24X7 hrs and consume total energy of 3 crore units annually at a cost of Rs 21 crore per year. By installing variable frequency drive in midpoint in 2021-2022 this consumption was reduced to half. These fans can rotate in one direction to work as exhaust fans.

The Metro authorities are now planning to replace these fans by axial fans which are suitable for two hour operation even if the air temperature it handles reaches 250 °C.

As learnt from the Kolkata Metro Railway office, a work order has already been placed on an Indian subsidiary of a Japanese company for upgrading Blue Line’s stations Environmental Control Systems (ECS) and upgrade the Tunnel Ventilation System (TVS). This holding company has already commissioned ECS and TVS systems in more than one hundred underground Metro stations in Singapore Metro. Team of Japanese engineers is said to have visited Jatin Das Park station air conditioning plant and other areas recently.

According to an official of the city Metro, once completed, passengers will have a more comfortable riding experience in Metro Railway, Kolkata, Asia’s fifth Metro network. This upgrade with state-of-the-art technology will also ensure improved fire safety and save Rs 11 crore annual electricity bill as well as reduce carbon footprint by 12,300 metric tonnes annually.

Apart from the TVS upgrade, the Metro authorities are also exploring options of constructing seven additional substations to improve train operations in the Blue Line. A work has been proposed to add under sanctioned ‘umbrella works’ including construction of seven additional sub-stations at Kalighat, Netaji Bhawan, Maidan, Esplanade, MG Road, Sovabazar-Sutanuti and between Belgachia and Shyambazar.

With this, Blue Line would have traction substations at each station like Purple Line and Orange Line. Apart from this, in order to meet the demand of additional traction power with fire safety, order for two traction sub-stations (TSS) at Chandni Chowk has already been placed to avoid congestion of rakes between Esplanade and Central stations where there are two TSS for four stations.