Kolkata Metro is set to join the elite Metro systems of London, Moscow, Berlin,
Munich and Istanbul which have composite aluminium third rail instead of
those made of steel. Third rail is live rail that provides electric power to a train
through a conductor placed alongside the rails.
Kolkata Metro Railway has now 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.
Kolkata Metro has floated a tender for the replacement of the existing third rail
to cover the section between the Dumdum and Shyambazar stations in the first
phase. 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 the
Mahanayak Uttam Kumar (Tollygunge) and Kavi Subhash (New Garia) stations
will be taken up.
The advantage of aluminium composite third rail over steel third rail is that
there will be a reduction in the resistive current loss and an 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 a 10 km corridor with the use of aluminium composite third
rail would require one less traction sub-station compared to steel third rail — a
straight saving of approximately INR 210 crore capital investment for 35 km of
the Metro corridor. The use of composite aluminium will also reduce the
maintenance and lifecycle cost. The energy saving using composite aluminium
third rail may be approximately 6.7 million (67 lakh) units per annum.
