Indian Railways introduces Asia’s largest Interlocking System

With more and more derailments happening in the past few months, the South Eastern Railway (SER), in a move to increase capacity and ensure the safer running of trains, has replaced the route relay interlocking (RRI) system at Kharagpur with Asia’s largest solid state interlocking (SSI) system. This technology will come into effect from Sunday, 19 November 2017 and will allow station masters at Kharagpur to set 800 different routes for trains in just a few clicks.

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This is in stark contrast to the vintage RRI system which only allowed operators to set a mere 423 routes. Principal Chief Operations Manager of SER, Suchitto Kumar Das said, “This will be Asia’s largest SSI system. The RRI system is of pre-1980 vintage and has crossed its codal-life.”

The cost of installing this new system is INR 39 crore. This new technology will allow the path of a train to be set in such a way that it has to cross several tracks. The main benefit of the interlocking system is that it ensures no cross movement taking place during the crossings which will help to avoid disastrous collisions.

“The SSI system is much more dependable than the older ones. We have been carrying out tests on this system for the last 7-8 months,” said Das.


The project that was kick-started at the Kharagpur yard on November 4, 2017, will continue its work till Sunday. It is likely, that passengers may face severe disruptions in the suburban rail services from Friday, once the SER begins to switch over to the SSI system from its current RRI system.