Indian Railways has installed Asia’s largest Solid State Interlocking (SSI) system in Kharagpur, which will enable station masters to set 800 different routes for trains in a matter of minutes. Interlocking is a railway signal apparatus that prevents conflicting movements of trains. Asia’s largest Solid State Interlocking (SSI) system has been installed in Kharagpur at a cost of Rs 39 crore. The cutting-edge technology replaces the pre-1989 route relay system that only allowed operators to set maximum 423 routes. The new system ensures that no cross-movement takes place.