What is a Signalling failure?

Related questions

1. Do trains have traffic lights?
2. What is a controlled signal?
3. What activates a train signal?
4. How does Indian Railway Signal work?
5. What's a red signal on a train?
6. What do train whistles mean?
7. What is fixed block Signalling?
8. How do train crossing signals work?
9. What do train signal lights mean?
10. How do automatic train signals work?

Tags

1. #signalling
2. #itself
3. #because
4. #whenever
5. #detected
6. #there
7. #equipment
8. #occurs
9. #normally
10. #cases
11. #signal
12. #fault
13. #track
14. #running
15. #working
16. #reasons
17. #system
18. #trains
19. #signals
20. #failure
21. #designed
22. #problem