India's first Metro stretch to be upgraded with aluminum third rails

Kolkata, June 15: India’s first Metro link, between Tollygunge (Mahanayak Uttam Kumar) and Dum Dum stations in Kolkata, is going through a major upgrade nearly 30 years after its completion. 

The 16.45 km stretch was completed in 1995 though trains were already running between the intermediate stations (the 3.4 km stretch between Esplanade and Bhowanipur) since 1984.

The Metro Railway has now taken up the replacement of the steel current conducting third rail with an aluminum one. This will not only be energy efficient, but also ensure faster running of trains. 

According to Metro engineers, the change will ensure 84 per cent reduction in energy loss, which is Rs 1 crore per year per km. 

For the entire stretch, this amounts to Rs 16.45 crore per year.

“Such replacements have already taken place in older Metro stretches in the world like in Singapore, London, Moscow, Berlin, Munich, and Istanbul. The new stretches that we introduced in Kolkata, such as the East-West and Joka-Taratala corridors, have aluminum third rails. 

"Work has already started from Noapara (the carshed beyond Dum Dum) and it is expected to be completed in the next two years. A German company has been entrusted with the project. Normal services will not be hampered during the upgradation process,” said Kausik Mitra, CPRO, Metro Railway.

The high-conductive aluminum third rail will have a stainless-steel top. It will have the capacity to reduce system voltage drops and subsequent energy losses, thanks to its superior electrical conductivity. 

This reduction in voltage drop in the third rail will allow quicker acceleration. This will also allow the Metro Railway to increase frequency during peak hours. The huge energy savings will bring down operational costs.

The expense involved in replacing the third rail would be realised within three years due to a drop in operational costs. 

Additionally, the aluminum third rail will reduce carbon emissions by 50,000 tonnes in its lifetime. The aluminum rail also requires less maintenance and will be highly reliable and stable in a hot and humid city like Kolkata. 

Less heat will also be generated inside the tunnel when the Third Rail Current Collector (TRCC) comes into contact with the third rail. No welding will be required to join two aluminum rails, as it can be done with the help of a splice joint. This will help in maintaining air quality inside the tunnel,” Mitra said.