Computer Based Interlocking Systems

Challenges faced by Computer based Interlocking Systems

 

1. The wiring from the field object such as Signals, Points and tracks to the SSI Rack is still done using Copper cables which amounts to huge costs
2. The hardware reliability and availability  factor is low compared to the system availability given by RRI
3. The fail safe mechanisms employed  in processor based equipment is not standard and often get untested during V&V activities
4. Lack of formal methods in developing the control algorithms (Interlocking Logic)
5. Lack of domain Knowledge in Signalling and Traditional Route Relay Interlocking Systems, This creates a technological gap between the software programmers and the Domain consultants. This leads to Errors in software, which might lead to unsafe failures of the system
6. Extending the working scope of the Interlocking systems  for monitoring and  other non-Interlocking functions, which leads to degraded performance of the system
7. Employing Non-Formal Interlocking principles instead of traditional RRI Principles leads to software complexity. For Ex: The Geographical method needs every system that is installed for new Yard needs validation, which is not practicable.
8. Since the software and hardware is so complex, complete test of the system is not possible and most of the faults are revealed at the field Installation stage or during normal working of the system in field.
9. The software is to be changed for every yard, the software structure should be in a generic form, but we seldom see a generic form and at this stage errors creep in.
10. The lack of standardization in the railway working principles and the core Interlocking principles, the software developers are forced to do changes in the software for every yard in Different railway zones.
11. Increase in the complexity of the software leads to difficulty in testing, since most of the Interlocking systems are sequential machines they are error prone and are very difficult to test.

With Increasing speed of trains, there needs to be a direct communication with the on board computer of the train (Engine), so that there is less human involvement and thus less human errors. But Interlocking systems are mostly not capable of sending commands to the on board computer of the train (Engine).

 

Any queries mail me at sandeep.patalay@cmcltd.com

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