Afternoon All,
Please see attached mod 2 2015 layout attempt and calculations.
Any advice, comments or questions very welcome.
I think I have made an error in the down branch entrance and exit signals.
I have already noticed that the dock line head shunt has not been numbered and is missing a MARI- any other obvious mistakes please let me know.
Many thanks.
(13-09-2018, 05:28 PM)REMBrum Wrote: [ -> ]Afternoon All,
Please see attached mod 2 2015 layout attempt and calculations.
Any advice, comments or questions very welcome.
I think I have made an error in the down branch entrance and exit signals.
I have already noticed that the dock line head shunt has not been numbered and is missing a MARI- any other obvious mistakes please let me know.
Many thanks.
A quick look and I have "spotted" several missing trap/catch points for goods lines etc (I'm assuming UK mainline since I can't see where you've said) Also the interrupters you have shown are wrong - any train over the points will break them the way you have shown them.
The single line is oversignalled IMO. I'd do One-Train-Working for Axle counters (like Windsor branch on the Great Western) so you'd need a fixed distant or distant board and bufferstop lights at H, with signals controlling entrance/exit to the branch roughly where you have 45/46R
Your points normal lies and numbering look good, and the traks around them - just one joint too many on the scissors.
A subsidiary signal (shunt/call-on from main signal) has just 2 lights on the diagonal, whereas a ground shunt signal has 3 - horizontal and diagonal (yours are creeping towards vertical).
I may be wrong on this, but I think the 37 second strike-in is for AHBCs which are not interlocked with signals. As MCB-CCTV crossings are interlocked, it needs to allow time for the barriers to be detected down and crossing clear given before an approaching train (driver) sees a caution aspect on the approach to the protecting signal. (i.e. 27s before sighting the YY before your signal 12 @R).
(13-09-2018, 07:29 PM)dorothy.pipet Wrote: [ -> ] (13-09-2018, 05:28 PM)REMBrum Wrote: [ -> ]Afternoon All,
Please see attached mod 2 2015 layout attempt and calculations.
Any advice, comments or questions very welcome.
I think I have made an error in the down branch entrance and exit signals.
I have already noticed that the dock line head shunt has not been numbered and is missing a MARI- any other obvious mistakes please let me know.
Many thanks.
A quick look and I have "spotted" several missing trap/catch points for goods lines etc (I'm assuming UK mainline since I can't see where you've said) Also the interrupters you have shown are wrong - any train over the points will break them the way you have shown them.
The single line is oversignalled IMO. I'd do One-Train-Working for Axle counters (like Windsor branch on the Great Western) so you'd need a fixed distant or distant board and bufferstop lights at H, with signals controlling entrance/exit to the branch roughly where you have 45/46R
Your points normal lies and numbering look good, and the traks around them - just one joint too many on the scissors.
A subsidiary signal (shunt/call-on from main signal) has just 2 lights on the diagonal, whereas a ground shunt signal has 3 - horizontal and diagonal (yours are creeping towards vertical).
I may be wrong on this, but I think the 37 second strike-in is for AHBCs which are not interlocked with signals. As MCB-CCTV crossings are interlocked, it needs to allow time for the barriers to be detected down and crossing clear given before an approaching train (driver) sees a caution aspect on the approach to the protecting signal. (i.e. 27s before sighting the YY before your signal 12 @R).
Many thanks Dorothy,
I have reviewed standards and you are correct regarding the MCB strike in.
The comments regarding the interrupters, scissors and the subs are all very useful.
Is the single line (excepting the lack of fixed distant approaching the buffer) inherently incorrectly signalling or just demonstrating poor economics? With such decisions in the exam is it best to state rationale for such decisions?
Much appreciated.
What do you think the extra signals gain for your layout? Or why are they a requirement?
They don't do much as there are no junctions to protect and it's single line. Token block working seems a better solution.
You need some way of protecting the single line - a token solution is OK and I think you'd get good marks for it if shown correctly.
I reason that if drivers need to stop to exchange tokens it may be a pain operationally. I'm suggesting one train working with axle counters because the layout is similar to the Windsor Branch ( GWR at Slough) and I've worked on it so am familiar. If the single line section starts at a station platform I'd be more tempted to use a token or staff like the Bourne End branch (GWR at Maidenhead).