Firstly I should point out (have to be careful not to be sexist) that there are also some ladies who utilise this Forum as well (indeed I know you know that)!
Then I should say it is good to hear from you again.
On a current NR Signalling Plan then it is the CP "Clearance Point" which is shown; this is where the track circuit joint or axle counter head has to be to be sufficiently far from the convergence that a train on one route just beyond it will not hit a train routed over the other lie of the set of points. Hence it is a =matter of looking for the associated arrow and looking at the track section division to see if it is "foul" or "clear". I'll try to post a diagram later.
The fouling point is the place where the vehicles would actually just touch- the clearance point is what we need to consider because
a) we want a "passing clearance" a minimum space between vehicles
b) the train detection only knows where the axles are and a vehicle always overhangs that position and indeed is wider than the rails it runs upon.
HOWEVER, the IRSE often do not depict and expect students to use "their signalling common sense". Broadly this means judging if the tracks when parallel are at "6foot" apart or if they must be wider (e.g. the approach to an island platform etc). If at 6ft then it is a reasonable assumption to say that the clearance point of a crossover is bang opposite the switch tongues of the point on the adjacent line; similarly judge "by eye" where there is just a single lead.
Then I should say it is good to hear from you again.
On a current NR Signalling Plan then it is the CP "Clearance Point" which is shown; this is where the track circuit joint or axle counter head has to be to be sufficiently far from the convergence that a train on one route just beyond it will not hit a train routed over the other lie of the set of points. Hence it is a =matter of looking for the associated arrow and looking at the track section division to see if it is "foul" or "clear". I'll try to post a diagram later.
The fouling point is the place where the vehicles would actually just touch- the clearance point is what we need to consider because
a) we want a "passing clearance" a minimum space between vehicles
b) the train detection only knows where the axles are and a vehicle always overhangs that position and indeed is wider than the rails it runs upon.
HOWEVER, the IRSE often do not depict and expect students to use "their signalling common sense". Broadly this means judging if the tracks when parallel are at "6foot" apart or if they must be wider (e.g. the approach to an island platform etc). If at 6ft then it is a reasonable assumption to say that the clearance point of a crossover is bang opposite the switch tongues of the point on the adjacent line; similarly judge "by eye" where there is just a single lead.
(16-07-2013, 10:33 AM)onestrangeday Wrote: Dear Gentlemen:
I would like to know how the fouling point is shown on the scheme plan?
It's best to have an example of scheme plan if someone is willing to share around
Thanks
PJW