Kolkata Metro Railway has decided to use composite aluminium third rail in all the upcoming corridors being undertaken for construction along with retro fitment in existing corridor with steel third rail. With this, Kolkata will become a member of the elite club of London, Moscow, Berlin, Munich, and Istanbul metros which have also shifted from steel third rail to aluminium third rail.

Kolkata Metro Railway, India’s first metro built by Indian Railways and launched on October 24, 1984, has been serving as a lifeline for Kolkata, the city of Joy for nearly 40 long years.

In Kolkata Metro Railway, the power to Metro Rake is supplied to rolling stock at 750V DC through steel third rail. The Third Rail Current Collector (TRCC) made of steel fitted on metro rake collects the current from Third Rail. Kolkata Metro Railway using steel Third Rail for the last 40 years.

Metro Railway Kolkata has floated a tender for replacement of existing third rail, in the first phase to cover the section between Dumdum to Shyambazar, the railway ministry said in an official release on Wednesday. In the second phase work would be taken up from Shyambazar to Central and J D Park to Tollygunge. In the third phase, the section between Mahanayak Uttam Kumar (Tollygunge) to Kavi Subhash (New Garia) shall be taken up.   So, total 35 RKm main line steel Third Rail shall be replaced in stages.

The obvious advantages of aluminium composite third rail over steel third rail are:

* Reduction in resistive current loss and improved Traction voltage level as the resistance of steel Third Rail is around six times higher than composite Aluminium Third Rail.

* On an average, for 10 km corridor with use of Aluminium composite Third Rail would require 01 no. less Traction Substation compared to steel Third Rail, i.e., a saving of nearly Rs 210 crore capital investment for a 35 km of Metro corridor.

* The reduced voltage drop shall facilitate achieving faster acceleration with the same rake available with Kolkata Metro Railway.

* Reduced maintenance and life cycle cost. The requirement of painting of Third Rail every 5 years may not be needed anymore. The frequency of measurement of Third Rail dimension may reduce significantly. There may be no possibility of damage due to rusting etc
 
* Improvement in the efficiency of train operations.

* Huge     improvement       in    Energy     Efficiency     and     reduction      in    carbon footprint.

* Estimated energy saving using composite Aluminium Third Rail may be approximately 6.7 million units per annum.

* Improved headway of the trains.