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Colour Light Signalling and Operating Critique Required


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31 minutes ago, bigP said:

P.S.  What do you use to draw these track plans - is it a bespoke program for this kind of stuff, or just your own graphics in a drawing program?  Looks good either way.

 

I don't have any fancy software .  These plans are just drawn by inserting shapes and text boxes in Microsoft PowerPoint.  The symbols for signals have just been drawn using a series of straight and curved lines or circles and then grouped, so that I can copy and paste the same symbol multiple times. 

 

I then just hit Control A (to select all), Control C (to copy) and Control V (to add to posts on RmWeb). 

Edited by Dungrange
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2 minutes ago, iands said:

Apologies for being pedantic, but the signals such as 103, 105, 112 etc., are drawn with "junction" indicators not "route" indicators (sorry, but this was drummed into me when I was a trainee with the S&T way back when).

 

My understanding here is that Junction Indicator is what is also known as 'feather' - ie a line of five white lights, whereas a Route Indicator is what is also known as a 'Theatre Box' and displays a number or letter.  I've been assuming that Junction Indicators are correct here, although I haven't actually specified a line speed. 

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As for the trap and Ground Signal at the Oil Sidings, I think that would all be controlled by the Ground Frame, which would have four levers.  The Signal Box would route a train into the loop and when the rear of the train is clear of crossing 304, this would be returned to Normal and locked.  The Secondman on the oil train would then unlock the Ground Frame (which can only be done when crossover 304 is locked Normal), which would allow him to reverse the trap point and set the point in the oil siding correctly and control the Subsidiary Aspect on LP108 and the Ground signal  to control shunting.  Once shunting is complete, the shunter would have to set both the Subsidiary Aspect on LP108 and the Ground Signal to On, and the points to Normal before the Ground Frame can be locked again, and only once the Ground Frame is locked will the Signal Box regain control over crossing 304.  At least that is the way that I understand this to work.

IMHO a ground frame here is complete overkill and a waste of resources. The trap and ground signal are better controlled by the box and all the shunter needs is a hand lever on the siding points. When ready to commence shunting the box sets the routes in and out of the sidings which can have 'opposing locking removed', the shunter does his thing and when finished the box just cancels the routes.

 

Same goes for the upside really, no need for a ground frame, if you want the yard staff to gfive permission for a train to enter a phone call is usually enough but you could have an acceptance switch to allow the route in.

Rgds

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4 hours ago, Dungrange said:

 

My understanding here is that Junction Indicator is what is also known as 'feather' - ie a line of five white lights, whereas a Route Indicator is what is also known as a 'Theatre Box' and displays a number or letter.  I've been assuming that Junction Indicators are correct here, although I haven't actually specified a line speed. 

That's right. A "feather" is a colloquial term (five white lights, although early versions only had three white lights), now referred to as "junction indicators" but when I was a trainee they were always referred to as "PLJI" (Position Light Junction Indicators).

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4 hours ago, Grovenor said:

IMHO a ground frame here is complete overkill and a waste of resources. The trap and ground signal are better controlled by the box and all the shunter needs is a hand lever on the siding points. When ready to commence shunting the box sets the routes in and out of the sidings which can have 'opposing locking removed', the shunter does his thing and when finished the box just cancels the routes.

 

Same goes for the upside really, no need for a ground frame, if you want the yard staff to give permission for a train to enter a phone call is usually enough but you could have an acceptance switch to allow the route in.

 

I'm assuming this is because there is a need for mechanical interlocking within the ground frame (which costs money) and then a need for interlocking between the Ground Frame and the Signal Control Centre (which costs more money) and therefore this becomes a more expensive option overall than simply adding the trap and GPLS into the main electrical interlocking in the Signal Control Centre. 

 

That therefore means that I need to allocate a point number to the trap point and a number to the GPLS along with the note that 'opposing locking removed'.  I had this on an earlier version, so I'll add that back in.  To be honest, I don't think I could be bothered operating the Subsidiary and Ground Position Light Signal On / Off for each out and back movement during the shunting operation, so leaving both on is certainly my preferred option.

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6 hours ago, bigP said:

Hi,

 

Hope you don't mind.  Extended the image a bit.

 

2014128743_Dungrange102.jpg.bff6146fc4202ad8d63263e130a45693.jpg

 

New Limit of Shunt on Down Main, Up direction, behind LP101.

New GPLS Down Main, Up direction behind 309B points.

LP105 - #1 Route Indicator for Branch.  Main aspect back to Down Main LP107 - same as for LP103!

New Two aspect Main on Branch - DB1.

 

To run round:

either;

LP105 Single Yellow only to LP107, to go behind LP205.

LP205 bang road to Limit of Shunt on Down Main, to go behind LP101.

LP101sub only to go back onto train in Down Loop.

 

or;

LP105 Single Yellow + #1RI for the Branch to DB1, to go behind LP112.

LP112 sub to go bang road to Limit of Shunt on Down Main, to go behind LP101.

LP101sub only to go back onto train in Down Loop.

 

In reality both could be provided for to give the Signaller options when busy - depends how busy the area is I suppose as to what signalling would be provided.

 

That makes sense.  Am I correct that in this case (highlighted red) LP112 will have to be changed, so that I'd have a Stencil Indicator above the Subsidiary Signal that can display two route numbers to distinguish between being given authority to enter an occupied Down Loop and being given authority to run wrong direction on the Down Main as far as the Limit of Shunt.

 

Running round via the Up Main (as was suggested much earlier) seems inherently safer than wrong direction running on the Down Main, but the advantage of wrong line running on the Down Main is that there is no need to find a path on the Up Main in the Up direction, so I would be able to run round, whilst also running a train on the Up Main.

 

As all of these signals are off stage, I'll assume that they are all provided and all of these options are open to the signalman.

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To be honest, I don't think I could be bothered operating the Subsidiary and Ground Position Light Signal On / Off for each out and back movement during the shunting operation

The shunter would not want to be doing it from a ground frame either! And neither would the signalman want to be distracted by it, hence the 'opposing locking removed'.

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On 05/02/2020 at 18:59, bigP said:

 

Personally I call them feathers, but then if I had said that some Southerner would have told me they are lunars ;)

 

Well, I was brought up on the Southern and to me a "lunar" is a bi-directional lunar white warning light for pw workers that were lit whenever a signal had been cleared for the adjacent track. They were installed at places like Borough Market Junction where there were reduced opportunities for pw workers to stand clear of trains and the sight lines for a look-out man were restricted. Like the Southern's three-light feathers, they had to be proved alight before the relevant running signal would clear.

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On 05/02/2020 at 16:07, Dungrange said:

 

 

Is this because if the branch is freight only, then there is a need for a trap point between LP112 and crossover 309?  I note that there were differences between the signalling at Drem and at Prestonpans, both of which have / had a similar layout.  At Drem the branch is a passenger line to North Berwick (and looks similar to what I've shown), but at Prestonpans, the branch is freight only (to the former Cockenzie Power Station) and access looks like it might have been controlled by an offset Subsidiary Signal from the signal on the loop (rather than a Junction Indicator).

 

 

the signal on the loop in the Pans (EA568) has a feather and subsidiary signal. I think the feather is a left over from the access to Blindswell with the subsidiary for access to Cockenzine as the mainline signal (EA572) also has a feather 

1.pdf

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21 hours ago, ajwffc said:

the signal on the loop in the Pans (EA568) has a feather and subsidiary signal. I think the feather is a left over from the access to Blindswell with the subsidiary for access to Cockenzie as the mainline signal (EA572) also has a feather 

1.pdf 260.51 kB · 4 downloads

 

I think you're right about the feather referring to the access to the Blindswell opencast.  The Signalling Records Society (https://www.s-r-s.org.uk/archivesignals/brscot.php) have the signal layout at Prestonpans as it was in September 1977, which was the date at which the boxes on the line were closed and control transferred to the Edinburgh Signalling Centre.  Neither signal EA568 nor EA572 has a feather at that time, but then the site at Blindswell didn't open until 1979.  The feather must have been added at that time.  The notes for the 1977 re-signalling refer to a ground frame at Cockenzie controlling the signal routes to the sidings, which seems to be subsidiary signals on EA568 and EA572 and a Ground Position Light Signal EA834.

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Okay,

 

I have two further questions about Signal Overlaps.

 

image.png.851e474ab5efaf822c11be24e753926e.png

 

At the moment, I've shown the distance between Signals LP 105 and LP 112 being far enough apart that the Overlaps on these two signals do not overlap.  Am I correct therefore in assuming that means the signalman can allow trains to approach these two signals simultaneously?   That is, LP 101 can display a yellow aspect with lit Junction Indicator at the same time as the signal in rear of LP 112 is also displaying a yellow aspect, even although these two trains are driving towards one another.  Both LP 105 and LP 112 would obviously be On and displaying a red aspect.

 

My follow on question is, when a train is shunting the Oil Sidings, does that mean that the branch can no longer be used (because crossover 308 lies within the Overlap of Signal LP105)?   There obviously isn't a safety issue taking a train on or off the branch when the train in the Down Loop is propelling wagons into the Oil Sidings or Unloading Facilities, but when a shunt movement is taking place in the opposite direction, I assume that the Overlap beyond Signal LP 105 is still required, albeit I think the Overlap can be reduced to as little as 45 m if there was a speed limit of 15 mph in the Down Loop.  Would there ever be a Ground Position Light Signal installed to limit the shunt manoeuvre, or would there be any other form of control that would permit a train to pass through the Overlap beyond Signal LP 105 during shunting?

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41 minutes ago, Dungrange said:

Am I correct therefore in assuming that means the signalman can allow trains to approach these two signals simultaneously? 

Yes.

42 minutes ago, Dungrange said:

My follow on question is, when a train is shunting the Oil Sidings, does that mean that the branch can no longer be used (because crossover 308 lies within the Overlap of Signal LP105)?

Yes, but!

60s practice, there would be no overlap for a shunt move from the oil sidings up to LP105. Current practice requires no conflict within 45m, so not necessarily a separate 45m overlap track.  Recent, but not absolutely current would have provided a separate 45m overlap only available when shunting from the sidings.  All three achieve what you want: freedom to run off (or onto) the branch when shunting the oil sidings.

Paul.

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14 hours ago, 5BarVT said:

60s practice, there would be no overlap for a shunt move from the oil sidings up to LP105. Current practice requires no conflict within 45m, so not necessarily a separate 45m overlap track.  Recent, but not absolutely current would have provided a separate 45m overlap only available when shunting from the sidings.  All three achieve what you want: freedom to run off (or onto) the branch when shunting the oil sidings.

 

Unfortunately, I'm not modelling 1960's practise - 'recent but not current' would be the best description.  That therefore means that I would need a minimum 45 m Overlap between the placement of LP 105 and the Clearance Point from crossover 308, which I'm unlikely to be able to accommodate (that's almost two feet in 00).  I want to move LP 105 as close to the Clearance Point of Crossover 308 as I can get (15 m?) to maximise the distance between LP 105 and LP 108 to accommodate the arriving / departing trip working.  It therefore looks as though the branch has to be out of use when shunting the oil sidings unless I were to add a GPLS around 30 - 40 m in rear of LP 105 that is preset by LP 101.  This GPLS would therefore effectively be the Limit of Shunt.  However, I'm not sure that's prototypical - the real railway is probably rarely so constrained for space to justify the extra cost.

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I think maybe you are being too literal here.  Most of us (and I think that includes you) have had to compress our (station) layouts in order to get them to a manaageable size.  I think as long as your scale 15m LOOKS like it is meant to be the real deal I doubt if anyone will  complain - and if they do quote rule 1.  I know that you are trying very hard to bring realism to your layout - but surely there are reasonable limits?

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7 hours ago, Dungrange said:

That therefore means that I would need a minimum 45 m Overlap between the placement of LP 105 and the Clearance Point from crossover 308, which I'm unlikely to be able to accommodate (that's almost two feet in 00).

Would it be better to transpose 308 and 309? In that way you have a reduced overlap the length of the first crossover when making a shunt move from the oil siding with a train going on or off the branch.

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5 hours ago, imt said:

I think maybe you are being too literal here.  Most of us (and I think that includes you) have had to compress our (station) layouts in order to get them to a manageable size.  I think as long as your scale 15m LOOKS like it is meant to be the real deal I doubt if anyone will  complain - and if they do quote rule 1.  I know that you are trying very hard to bring realism to your layout - but surely there are reasonable limits?

 

I agree that there is always a need to compromise - my trains will only be half the length that I'd like them to be!

 

The minimum distance from a signal to the facing point toes is apparently 15 m, which scales out at 197 mm or about 7 3/4 inches.  How much can I compress that distance, such that it still looks right?  I'll accept six inches and five inches is probably okay, but I'd have thought anything less that about four inches would tend to start to look wrong.  I am hoping that between the Clearance Points of crossovers 304 and 308, I will be able to fit a Class 60 with six TEA tank wagons and still have at least a foot and a bit to spare, so that I can get close to the 15 m at each end.  If it's a bit short, I'll live with it.

 

The problem is that if the Offset needs to be a minimum of 45 m, that scales to 590 mm or 23 1/4" and if I may end up with Signal LP 105 just six inches from the conflict point at crossover 308, it will never look like 45 m.

 

42 minutes ago, TheSignalEngineer said:

Would it be better to transpose 308 and 309? In that way you have a reduced overlap the length of the first crossover when making a shunt move from the oil siding with a train going on or off the branch.

 

I can see how that would work in the real railway and indeed I think there seems to be a few more loops that actually look like that from looking at Quail Maps.  Whether I can make it work in the model, I'm not sure.  The problem is that the section to the left of the over bridge will effectively be hidden (ie it's within the fiddle yard throat, which will have tighter curves and lots of point work) and therefore what I have drawn will only exist as drawn on the signal control panel.  From a viewers point of view, the trains coming off the branch would therefore simply appear as though they are running wrong direction on the Down Main, which visually isn't as pleasing as a train obviously coming off the branch and crossing the Down Main.

 

However, looking at my proposed fiddle yard point work, I could probably slide point 308B to being the other side of the scenic break, so that in effect only half of the branch crossover (ie 308A) is actually visible, which might allow me to increase the length of the loop slightly and if I leave LP 105 where it is, then I may be able to get something that looks closer to 45 m, even if it's not quite the scale distance. 

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6 minutes ago, TheSignalEngineer said:

Depends on when it was resignalled and what locking is applied. Could be as little as 3.2m, or in the case of Birmingham New Street there used to be one at 1.7m.

 

Okay - if I can legitimately move LP 108 closer to point 304B, then I should be able to create a bit of extra distance between LP 105 and crossover 308, so that it might at least look like it could be 45 m.

 

My understanding of the 15 m distance is that it's broken down into 5 m between the signal and the Signal Replacement Joint and then a further 10 m between the Signal Replacement Joint and the Clearance Point or point toes, albeit this is where I get slightly confused, because I understood the point toes to be the Fouling Point and that the Clearance Point should be 4.88 m from the Fouling Point, so I'm not 100% certain whether I should be using 15 m or 19.88 m, but I think that's largely academic when I may have to apply a bit of compression.

 

What sort of time period would I have to assume for the signalling to use a smaller distance and would the Signal Replacement Joint then be at the signal or at the the rail joint that's a couple of sleepers back from the stretcher bar of the facing point?

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10 hours ago, Dungrange said:

 

Okay - if I can legitimately move LP 108 closer to point 304B, then I should be able to create a bit of extra distance between LP 105 and crossover 308, so that it might at least look like it could be 45 m.

 

My understanding of the 15 m distance is that it's broken down into 5 m between the signal and the Signal Replacement Joint and then a further 10 m between the Signal Replacement Joint and the Clearance Point or point toes, albeit this is where I get slightly confused, because I understood the point toes to be the Fouling Point and that the Clearance Point should be 4.88 m from the Fouling Point, so I'm not 100% certain whether I should be using 15 m or 19.88 m, but I think that's largely academic when I may have to apply a bit of compression.

 

What sort of time period would I have to assume for the signalling to use a smaller distance and would the Signal Replacement Joint then be at the signal or at the the rail joint that's a couple of sleepers back from the stretcher bar of the facing point?

The fouling point applies at the heel end of a point and is the spot where a vehicle on one line approaching a trailing point whould foul a vehicle on the other line approaching a trailing point.  So it will be nowhere near the toe of the point.

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33 minutes ago, The Stationmaster said:

The fouling point applies at the heel end of a point and is the spot where a vehicle on one line approaching a trailing point would foul a vehicle on the other line approaching a trailing point.  So it will be nowhere near the toe of the point.

 

Okay, I understand that in relation to a single point, but a crossover is formed by two points that are heel to heel with the extremities of the crossover being the toe of one or other of the points.

 

Just to clarify, is the definition of the Fouling Point intended to be the point at which two vehicles would actually or theoretically touch, or the point at which the clearance between two vehicles starts to become less than is provided between two vehicles on parallel tracks with the standard six foot between them (which I understand to be about 18")?  My understanding is, perhaps wrongly, that the Fouling Point is the latter and therefore when the wheels of a vehicle move onto the toe of a point that forms a crossover, that vehicles starts to be deflected towards the opposite running line and therefore this is the Fouling Point.  The Fouling Point would then have to be at the same Chainage on both running lines, but which is effectively defined by the toes of the points on one or other running line.

 

However, I can see in the situation I was referring to, the Down Loop will have to be 10' from the Down Main, which means that the Fouling Point / Clearance Point in advance of LP 108 needs to be defined with reference to point 304A (which will be traversed in the trailing direction) rather than 304B, which is facing.

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7 hours ago, Dungrange said:

Just to clarify, is the definition of the Fouling Point intended to be the point at which two vehicles would actually or theoretically touch, or the point at which the clearance between two vehicles starts to become less than is provided between two vehicles on parallel tracks with the standard six foot between them (which I understand to be about 18")?  My understanding is, perhaps wrongly, that the Fouling Point is the latter and therefore when the wheels of a vehicle move onto the toe of a point that forms a crossover, that vehicles starts to be deflected towards the opposite running line and therefore this is the Fouling Point.  The Fouling Point would then have to be at the same Chainage on both running lines, but which is effectively defined by the toes of the points on one or other running line.


Hi,

 

As I define in the book, the fouling point is where two trains on converging lines will touch. That is defined as the point where the distance between the nearest running rails is ~2m (sorry I can’t remember the actual number is at the moment and I don’t have access to the standard at home) measured perpendicularly from each running rail.

 

For a model railway, take the fouling point as the where two trains physically touch as the real

life distance does translate due to the under scale track work.

 

For a crossover in a standard 6 foot, you can pretty much assume that the fouling point is at the point toes on the other line. So on your layout, the fouling point for, say, 307A points would be, assuming a stand six foot, at the point toes for 307B and visa versa.

 

The clearance point would then be 4.88m (latest RIS says 5.88m, but we’ll ignore that for the moment) back from the fouling point. Again, for a model railway if you are really pushed for room, you could compress this distance to be the distance of the longest ‘overhang’ (distance between wheel and buffer face) of your rolling stock. Personally though I would just scale down the 4.88m.
 

The minimum distance between signal

and clearance point ideally is 15m, I always try to provide it in new designs and is a sort of ‘unwritten’ standard minimum among designers where there are no constraints. You can reduce it further as people have suggested, but only really where you have space constraints.
 

Ive been following this thread a little, but it’s grown so quickly that I haven’t been able to keep up, however the plan presented at the beginning of the thread was not incorrect given the operating requirements that Dungrange was hinting at.

 

Simon

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1 hour ago, St. Simon said:

As I define in the book, the fouling point is where two trains on converging lines will touch. That is defined as the point where the distance between the nearest running rails is ~2m (sorry I can’t remember the actual number is at the moment and I don’t have access to the standard at home) measured perpendicularly from each running rail.

 

For a model railway, take the fouling point as where two trains physically touch as the real life distance doesn't translate due to the under scale track work.

 

For a crossover in a standard 6 foot, you can pretty much assume that the fouling point is at the point toes on the other line. So on your layout, the fouling point for, say, 307A points would be, assuming a stand six foot, at the point toes for 307B and visa versa.

 

The problem is that the statements in black bold, don't seem to align very well.  If I take two Peco large radius points and lay these such that they represent a crossover at 45 mm track centres (as per a 'scale' crossover across a standard width six foot) and then place a Hornby Mark 3 coach traversing the crossover, I can move another Hornby Mark 3 coach around 110 mm (a scale 27' 6" or 8.3 m) beyond the point toes on the other line before the two coaches come into physical contact - see below.

 

Obviously if I were to replace Peco's 'large' radius points with scale length point work, then the distance would be greater and I could possibly get an entire coach length in between the point toes and the actual physical conflict point.

 

1180017860_IMG_20200221_2136491.jpg.a4dec9dbd30f80828804f7d2bac34cab.jpg

 

That's why I'm not convinced that the Fouling Point is actually the true physical conflict point between two items of stock but is instead the point at which the clearance between two vehicles is considered sub standard (ie less than around 18").  Effectively it would be the point at which the kinematic clearance envelopes of the items of rolling stock touch. 

 

At a standard crossover, the six foot distance (1829 mm) is measured from the outside of one rail to the outside of the other rail.  The rail head width is around 70 mm, so if I add 70 mm + 1829 mm + 70 mm, then the distance between the inside faces of the two parallel running lines (Up line and Down line) must be around 1969 mm.

 

I understand that the fouling point at a junction is the point where the distance between the running edges of the adjacent rails on both lines is 1970 mm, measured at right angles from the line carrying the passing train.  This is your statement (~ 2m) that I've highlighted in red and clearly this is wholly consistent with the assertion that the Fouling Point should be at the point toes.  I therefore believe that this statement is correct as is Figure 125 in your book.  The only statement in your book that I'm not convinced is correct is the sentence that states "the fouling point for single-end and non-standard crossovers should be measured on a model by taking two pieces of rolling stock and marking where they make contact".  However, given most modellers desire to compress distances, that's arguably largely academic. 

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Hoping that this will add a bit of clarity, I’m using old imperial distances ‘cos I’m old!

Fouling Point (FP) is where trains will touch.  (These days it’s could touch taking kinematic envelope into account I.e. sway etc.)  In the absence of detailed calculation by a gauging engineer it’s taken as 6’ (again from memory) between running edges perpendicular to the line concerned.

Clearance Point (CP) is 16’6” further away to allow extra clearance (18” in old money) for heads stuck out of windows etc.

Translating to Peco track at standard Peco centres using medium points and Mk1 rather than Mk3 coaches I have found about 5” from the end of the Peco Point to give me 6mm passing clearance.

11 hours ago, Dungrange said:

That's why I'm not convinced that the Fouling Point is actually the true physical conflict point between two items of stock but is instead the point at which the clearance between two vehicles is considered sub standard (ie less than around 18").

So what you have described there is CP not FP, but your reasoning is spot on.

 

11 hours ago, Dungrange said:

Effectively it would be the point at which the kinematic clearance envelopes of the items of rolling stock touch. 

And that is FP.

CP is what matters, FP is just part of the method of getting there, especially if using a calculated CP.

Hope this helps,

Paul.

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