A good attempt in general, but some comments:
1. Biggest error was the omission of the flashing aspect sequence; the symbol for the flashing yellow is on 107 and 109B route box shows MAY-FA. However it does seem odd that they have not shown more signals on the approach! Also to current standards (post Colwich) it seems improbable that one would permit a flashing sequence up to 135 at red (but actually, since the overlap extends sufficiently to lock out conflicts, then a SPAD at 135 would at least be safe). I suppose that giving a train a flashing aspect up to a red does ensure that the Main lines are cleared quicker, but I doubt whether would provide it in reality unless the train was to run non stop around the curve.
2. It is ambiguous how the lines which are broken at the break marked A-A are supposed to join up- "top to top" or "wrapped around the curve".
You have followed the route box for 109, but would have been worth a note, since the single yellow at 135 would be enough braking to stop at 123 so strictly could have given a green.
3. Hadn't specified a value for t4- it would be low or even zero depending on whether there is risk of seeing the main aspect before PLJI readable.
4. Do suggest that using dashed lines for approach release and greater clarity where aspect sequence lines join where there are both 3 and 4 aspect sequences converging does make the chart far clearer.
5. You did not interpret which signals to include / exclude the same as I did. I don't think the wording is entirely clear, but I think if you re-read question paper then you will see that your answer doesn't completely match. Feel you also applied #1 to wrong portion.
1. Biggest error was the omission of the flashing aspect sequence; the symbol for the flashing yellow is on 107 and 109B route box shows MAY-FA. However it does seem odd that they have not shown more signals on the approach! Also to current standards (post Colwich) it seems improbable that one would permit a flashing sequence up to 135 at red (but actually, since the overlap extends sufficiently to lock out conflicts, then a SPAD at 135 would at least be safe). I suppose that giving a train a flashing aspect up to a red does ensure that the Main lines are cleared quicker, but I doubt whether would provide it in reality unless the train was to run non stop around the curve.
2. It is ambiguous how the lines which are broken at the break marked A-A are supposed to join up- "top to top" or "wrapped around the curve".
You have followed the route box for 109, but would have been worth a note, since the single yellow at 135 would be enough braking to stop at 123 so strictly could have given a green.
3. Hadn't specified a value for t4- it would be low or even zero depending on whether there is risk of seeing the main aspect before PLJI readable.
4. Do suggest that using dashed lines for approach release and greater clarity where aspect sequence lines join where there are both 3 and 4 aspect sequences converging does make the chart far clearer.
5. You did not interpret which signals to include / exclude the same as I did. I don't think the wording is entirely clear, but I think if you re-read question paper then you will see that your answer doesn't completely match. Feel you also applied #1 to wrong portion.
(08-07-2013, 10:35 AM)dorothy.pipet Wrote: Another attempt for comments please
(untimed and open book)
Dorothy
PJW