See attached comments upon some attempted calculations for this layout.
Actually this was an unusual layout since the through station has a severe speed restriction through it and therefore even non-stopping trains have to slow down and therefore stopping headway type calculations dominate. Also the headway requirement combined with the slow speed means that closely spaced signals are needed.
These calculations are not the easiest to follow but broadly along the right lines. Certainly they would have taken far too long in exam conditions, so a "quicker and dirtier" approach is probably called for.
Many candidates tend to ignore stopping calcs completely since believe there are easier marks to gain elsewhere in the paper, but the examiners occasionally "retaliate" by coming up with a layout that really needs them. It is one thing to decide within the exam that your time is better spent on doing something else, but it unwise to completely ignore during your pre-exam preparations because you run the risk of being presented with a layout for which they are unavoidable and then you would then be insufficiently prepared. Definitely worth thinking prior what you'd do when faced with such a layout!
Actually this was an unusual layout since the through station has a severe speed restriction through it and therefore even non-stopping trains have to slow down and therefore stopping headway type calculations dominate. Also the headway requirement combined with the slow speed means that closely spaced signals are needed.
These calculations are not the easiest to follow but broadly along the right lines. Certainly they would have taken far too long in exam conditions, so a "quicker and dirtier" approach is probably called for.
Many candidates tend to ignore stopping calcs completely since believe there are easier marks to gain elsewhere in the paper, but the examiners occasionally "retaliate" by coming up with a layout that really needs them. It is one thing to decide within the exam that your time is better spent on doing something else, but it unwise to completely ignore during your pre-exam preparations because you run the risk of being presented with a layout for which they are unavoidable and then you would then be insufficiently prepared. Definitely worth thinking prior what you'd do when faced with such a layout!
PJW