11-08-2016, 11:17 AM
In your diagram, you appear to have all signals spaced at braking distance but you have called them two aspect signals.
In 2 aspect signalled areas, the block length is between two R/G signals (which would be very much greater than braking distance) and each R/G signal has a Y/G signal associated with it at braking distance. You would never have, as you have in your diagram, R preceded by G.
If the block length is such that signals need to be spaced near braking distance, 2 aspect signalling is not economic and 3 aspect is likely to be the solution.
In 2 aspect signalled areas, the block length is between two R/G signals (which would be very much greater than braking distance) and each R/G signal has a Y/G signal associated with it at braking distance. You would never have, as you have in your diagram, R preceded by G.
If the block length is such that signals need to be spaced near braking distance, 2 aspect signalling is not economic and 3 aspect is likely to be the solution.