AMAR METRO
KOLKATA
PRESS RELEASE
REPLACEMENT OF STEEL THIRD RAIL WITH ALUMINIUM THIRD RAIL COMPLETED IN BETWEEN MAHATMA GANDHI ROAD AND CENTRAL STATION
Kolkata, 24.11.2024
Metro Railway, Kolkata country's first Metro has undertaken an ambitious plan of replacing its Steel third rail with Aluminium third rail in Blue Line and gradually has been progressing with the work. on completing 40 years glorious service to the Nation, our Metro successfully replaced the Steel third rail with Aluminium third rail on the main line at Central station last night. With the implementation of this plan, our Metro now belongs to the league of London, Munich, Moscow and Istanbul Metros.
At least fourteen countries of Asia use the third rail system for providing DC traction power to its rakes. Kolkata Metro has been the fifth in Asia to have a Metro system. Kolkata Metro and Hong Kong Metro were first two Metros in the world to come out with solutions of Cooling Stations / Tunnels. Both Metros designed differently and both cooling systems have been working successfully even after 40 years of design.
Similarly Steel third rail, manufactured by SAIL, a central government PSU, has been providing power to rakes successfully for 40 long years in Kolkata Metro. With the evolution of technology, advanced systems of the 80’s are becoming irrelevant and energy inefficient in today’s era driven by green technologies. Keeping in mind the above facts, the Ministry of Railways has decided in 2012 that all new Metro Corridors will be built with Aluminium third rail. Accordingly, all Corridors of Metro Railway, except 40-year old Blue Line are having Aluminium third rails.
After implementing Aluminium third rail in Green Field Projects, Ministry of Railways has decided to replace Steel third rail of 34-km length of Blue Line. Accordingly open tenders were floated and contracts were awarded to Indian subsidiary of REHAU Group Company who assured that more than 60 % of contract value shall be sourced from India and remaining from Germany.
All of us are aware that on 07.09.24, 14.09.24 and 28.09.24, Kolkata Metro successfully replaced Steel third rail of its two-yard lines at Girish Park & Maidan and mainline at Central station by Aluminium third rail brought from Germany with remaining components procured from India engaging local work forces under supervision of Metro Railway Engineers headed by Shri Sumit Kayal an officer of Joint Director Level. After successful replacing of yard line's and main line’s third line, team headed by Shri Sumit Kayal took the challenge on the night of 23.11.24 to replace SAIL manufactured Steel third rail by Aluminium third rail of the main line in between Mahatma Gandhi Road and Central station and completed the work successfully.
Challenge before the team was to complete the entire work perfectly so that commercial service did not get affected. This replacement work was as good as commissioning of a new system with addition to removal of the old system. The section is approximately 650 meters in length in DN line.
It is to be noted that there are three types of rakes with three different types of TRCC. 13 BHEL AC rakes are provided with an older design of TRCC suitable for Steel third rail . Medha rakes and Dalian rakes are provided with TRCC suitable for Aluminium third rail but of different make. TRCC of Medha and Dalian rakes are bogie mounted whereas TRCC of BHEL rakes are axle mounted.
For this work, detailed engineering, manufacturing of components and site preparation were done in phases. Considering the Government of India’s green initiative in mind General Manager Shri P Uday Kumar Reddy has emphasized to implement the project on a fast-track basis. GM has been regularly monitoring the progress of this work. First phase materials were received in the first week of August 2024 and the second lot of third rail has already been inspected.
The replacement work was extremely critical and demanding as delay in completion of work might lead to traffic disruption in the next morning. So, all steps were monitored critically and after detailed minute to minute planning, back up planning and fallback strategy in place the work was executed. New pedestals were made of appropriate height with M65 pre mix concrete which is used in making piers of Metro viaduct so that required strength is obtained within a day of erection. All materials like third rail components and shroud boards were brought to the site and kept in a safe location and old shroud boards of existing rails were removed. on the execution night i.e. 23rd/24th November, existing Steel rails were cut at marked locations and dismantled. After that it was a race against time. New GRP (Glass Reinforced Plastic) insulators were placed on pedestals of M65 concrete abandoning old porcelain insulators and their pedestals. Then the new highly conductive Aluminum third rail was placed on insulators. The height and distance of the rails were adjusted. Interconnection between existing power supply systems was done with cables. After that adjustments of mid-point anchor, expansion joints and cable connectors, one final checking of tightness of all fasteners was done. Finally, the shroud boards were placed on the rail. This shroud board is fire resistant with a low smoke generator in case of fire.
Aluminum’s electrical conductivity is 38 million siemens per meter whereas Steel has value of 6 million siemens per meter. This physical characteristic of Aluminium helps to attain lesser voltage drops and lesser energy losses compared to Steel third rail. Apart from nearly no voltage drop, the third rail will help to achieve faster acceleration of the train and reduce the head way of running Metros. As a result, the entire additional expenses for replacing this third rail shall be realized within five years through saving in operational cost. Additionally, Aluminium third rail will reduce carbon emission by 50,000 tons in its lifetime.
Apart from this, Aluminum third rail will require less maintenance and have more codal life because of absence of corrosion. Aluminum weighs 169 pound /cubic foot and steel weighs 490 pound / cubic foot. So manpower required to handle Aluminium third rail is much lesser. New third rail will not require any welding as two Aluminum rails can be joined with the help of splice joint. It will help to maintain the air quality inside the tunnels and shall have no risk of cable fire while welding.
Aluminium third rail will also reduce heat load to the AC system as inside the tunnel lesser heat will be generated for the low resistance value of the Aluminum compared to Steel.
Kausik Mitra
Chief Public Relations Officer
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