(14-09-2010, 08:44 PM)merlin89 Wrote: PeterFirstly don't worry too much about precise time values; just aim to get an approx value: 5 sec, 15 sec, 30 sec, 60 sec etc.
I seem to be having a few issue re my lengths of TC from the layouts and as such is hampering my ability to grasp the principle of which time to use fromyour time values doc. for example the OL for 113A(W) is 50m which is less than the minumum of 55 ( however is marked up as O/L and not ROL) so Im assuming a time value of 0sec; the issue with the layouts is I cannot guage how long a track is e.g. tracks AL or Am at Platform 1 or even tracks BM and BN at platform 2 how can you figure out their lengths for timing of overlaps. Same goes for Approach release track ccts. Can you help please?
Kind regards
Ian
Sometimes it is a guess but use what you know or can assume:
signal spacings are often given, overlaps are probably 180m, train lengths are often given - from which lengths of plaformas can be inferred (e.g if there is a call-on PL then platform may well be twice the train length).
The minimum ROL is 50yds = 45m. As a generala rule of thumb I say that a signal for a (W) should clear when the train is as far from it as the length of the ROL beyond the next signal, timing for a few seconds is sensible even with a 100m berth TC.
AL+ AM = 542 - 220 so we actually know the combined length exactly, but I'd just take to be 300m
AH = 600 - 180 so it is clearly just over 400m
PJW