well even i dont know much abt RRI, except for the fullform :P
anyways, this is what IRFCA has to say-
"Route Relay Interlocking (RRI) is the system used in large and busy stations that have to handle high volumes of train movements. In this, an entire route through the station can be selected and all the associated points and signals along the route can be set at once by a switch for receiving, holding, blocking, or dispatching trains"
seems...
more... to be the bigger version of that lever operated new bongaigaon east west cabins...