August 31, 2023: The Kolkata Metro has decided to use composite Aluminium Third Rail in all the upcoming corridors. The metro has for the past 40 years relied on steel Third Rail. With this the Kolkata Metro Railway will join the elite club of metro networks in London, Moscow, Berlin, Munich and Istanbul that have shifted from steel Third Rail to Aluminium Third Rail.
Source: PIB
The metro has already floated a tender for replacement of 35 km mainline steel Third Rail in a phased manner, it said in an official statement. Phase-1 of the project will cover the section between Dumdum to Shyambazar, Phase-2 between Shyambazar to Central and J D Park to Tollygunge, and Phase-3 between Mahanayak Uttam Kumar (Tollygunge) to Kavi Subhash (New Garia).
What is a third rail?
Source: PIB
A third rail is an additional rail, lying alongside the or between the two main rails. It is used to provide power supply to trains, trans and other rail vehicles.
Advantages of aluminium composite Third Rail
Less energy loss: Resistance of steel Third Rail is around six times higher than composite Aluminium Third Rail. This will result in a reduction in resistive current loss and improved traction voltage level. The reduced voltage drop will facilitate achieving faster acceleration with the same rake available with the Kolkata Metro Railway.
Capital saving: A 10-km corridor of Aluminium composite Third Rail requires one less traction substation compared to steel Third Rail, helping save approximately Rs 210 crore capital investment for a 35-km Metro corridor.
Reduced maintenance and life cycle cost: The need to paint the Third Rail every 5 years may not be needed anymore. The frequency of measurement of the Third Rail dimension may reduce significantly. There may be no possibility of damage due to rusting, etc.
Improved operations: The switch will enable an improvement in the efficiency of train operations. Improved headway of the trains.
Energy saving: The switch will result in huge improvement in energy efficiency and reduction in carbon footprint. The estimated energy saving using composite Aluminium Third Rail may be approximately 6.7 million units per annum.
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