Rail interlocking system

Rail interlocking system

Context:

• An electronic track management system used by the Railways has become the focus of investigation after the multi­train crash in Balasore district of Odisha.

What is an interlocking system?

• Railway traffic is controlled and managed by railway signalling.
• Interlocking, an integral part of it, involves a set of apparatus placed on a track to manage the safe movement of trains and track configuration at stations and junctions.
• It prevents conflicting movements as a train gets a signal to proceed ahead only when its route is set, locked, and detected as safe.
• The signal apparatus in an interlocking system may be interconnected mechanically or electrically with the tracks or both.
• Electronic interlocking (EI) is an advanced version of signalling that uses computer­based systems and electronic equipment to control signals, points and level­crossing gates.
• The three components that form the basis of an electronic interlocking signal system are: Signal: Based on the status of the track ahead, light signals direct a train to stop (red light), proceed (green), or exercise caution (yellow).

How does the system work?

• The system receives a command, following which information is collected from the yard and processed to set a safe route.
• The determined route is aligned, and signalling devices are interlocked at a particular position.
• A signal to pass is given based on which direction the track is set and whether the divergent track is free of obstruction.
• If a train is required to switch lines, then the system will direct it to the empty track at the point where two lines meet.
• Track circuits, meanwhile, prevent multiple trains from running on that block to avoid a collision.
• All points remain locked until the train has crossed a particular section of the track in use or the signal to proceed has been withdrawn.
• In case there is a failure in the system, the red light will be flashed, indicating that the route ahead is not clear or safe.

What caused the Odisha train crash?

• A preliminary probe by Railways officials has found that a problem with the signal system could be the cause of the accident at Bahanaga Bazar railway station on the evening of June 2.

Syllabus: Prelims