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Lichfeldian

Three Way Points Permitted on Main Lines?

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I new to this forum and am at the start of creating a layout in my loft after years of dithering and false starts. As I have sufficient length and width for it, have roughed out a design based on Tresco in C J Freezer's PSL book of track plans. I know some regard these as rather old hat now, but the station layout in Tresco is a bit different from the usual, in that it has a central bi-directional loop line between the platform tracks, allowing freight trains or expresses to by-pass stopping trains. I have simplified the plan a little, particularly at the left hand end where (if you have access to the plan) there is a complicated collection of intersecting points and crossings that I couldn't seem to translate from the lines on the plan into actual Peco Streamline track pieces, without it becoming impossibly large. Another simplification I am considering, is replacing successive right and left hand points at the right hand entry to the station controlling the split from two to three through tracks, access to a slip point to the right and to a back platform loop to the left, with a three way point to save space.

 

My question is: prototypically, would a three way point be permitted on a through main line, or were these only found in sidings, etc? A second question (which ought to be on the signalling queries part of this forum - sorry!), is how would this 2-3-2 track formation be signalled in the 1930s LNER steam era please? I'm guessing that a fully prototypical scheme would probably be too complex to create in the space available, but I would like to have some arrangement of signals (initially non-working) that would look reasonably true to life, if possible. Could anybody advise on either or both of these please? Regards and thanks.

 

Lichfeldian

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Hi just swung by to wish you welcome to the RMWeb collective. Someone be along soon enough to help you out!

 

Cheers,

 

Philip

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No particular rule against three-way points as part of the throat of a station where trains are all moving slowly. They do, of course, need two facing point locks in the situation that I think you are describing.

 

In more rural locations, you might still find three-way points on the main running line but nearly always in the trailing direction.

 

CJF plans (I am not familiar with this one) are usually set out in a way that is fairly true-to-life, so signalling should not be a problem. But, as ever, a lot of the signalling will probably be off-scene. Still good to keep it in mind when designing the layout.

 

If you can upload your version of the plan here, there are people who will help you with the right locations and types for the signals.

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Three way points come in two main types, Tandems where the two sets of blades follow each other and Three-throw where the two sets of blades overlap. The three-throware strictly sidings only. The Tandem are acceptable in main lines and were quite common.

 

Signalling advice will be easier to give with a sketch plan of the layout, many of us do not have handy copies of CJF's plans.

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Facing three way points of any sort were not liked on running lines at anything other than where speeds were very low so hardly likely at a wayside intermediate station on the through running lines.

 

the layout is regrettably a little bit of the typically somewhat over-optimistic  CJF approach to track plans with far too many facing points, including facing crossovers, for an anything like normal steam period British outline track layout while even wordse the end near the turntable incoporates what appears to be a double slip although the job could be done quite well with a single slip.  Alas the track layout is far from suitable for using the middle line as a goods loop as there is really very little room to insert the necessary trap points - which would have to be wide-to-gauge traps in any case.

 

If you want to use the plan as a basis for arriving at a more prototypically realistic track layout then it does have some potential and I would start by deciding exactly what you want to use that middle line for - with a bi-directional goods line coming a long way down the various options due to the difficulty in arranging in it in a prototypical manner in the space available - assuming you are of course looking for a prototypical looking layout?

 

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Thanks for the responses. In reply to The Stationmaster, I had already substituted a single slip for the double slip accessing the bay platforms to the right. Would this be OK on a through line? I have also deleted the turntable and used the exit to it and the coaling stage from the bay platforms as the start of a single track branch.

 

However, it is a tad disappointing to discover that the whole basis of the plan is non prototypical! I'd assumed that as it was produced by a railway modeller of significant note in his day, that it would be reasonably authentic. I must admit that trap points issue hadn't occurred to me and although Peco do produce them, I don't recall seeing them commonly fitted in model layouts, perhaps for reasons of space. Not being familiar with "real" railway practice, I don't know what a "wide to gauge" trap would look like.

 

I had rather liked the plan as being a bit different and I'm reluctant to start yet again on another plan. I could easily replace the three way point with the successive right and left points, as on the original plan, although they would still be facing points of course. I do know that the old railway companies tried to avoid them, but again this seems to something frequently seen on model layouts. Otherwise, how could platform loops be laid out? What other alterations could do to make it more prototypical? What other use could the centre road have? 

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42 minutes ago, Lichfeldian said:

What other use could the centre road have? 

 

The Great Central laid them out as middle sidings (see Sheffield Victoria - Grimsby was similar) connected like a long crossover with a trailing point at each end.  No use for through running of course.

 

If you do want trains to overtake, a loop each side with two through lines would be a frequent solution.  Add a trailing crossover at each end and you have a workable station that can easily terminate and reverse trains.  If you need to save length, you can bring the crossovers inside the loops using a single slip as here at Lincoln (an additional slip needed because of the extra loop platform face), which also shows bays and/or dock roads on the departure side.

 

 

Edited by Flying Pig
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I think that CJF is using “artistic license” to create something that looks authentic to most observers and, of course, he has to make compromises to compress track plans into the space available and to use the RTL parts available.

 

Remember that the OO RTL trackwork Is itself a compromise because of the radii, gauge, flangeways, etc.

 

CJF may be using double slips in running lines to compress what In the real world would be two separate crossings, into one. Whether you feel you can accept that compromise is down to the level of fidelity to the prototype you are aiming to achieve.


Trailing slips in running lines are fine.

 

Obviously, facing points leading to loops are unavoidable. In the real world they would be protected by extra infrastructure and probably speed restrictions, which are again a matter of fidelity for the individual modeller. 

 

Trap points are often omitted from model railway plans for compression and because most people wouldn’t use them in the prototypical way. (More fidelity.)

 

Having said all that I can see what Mike is getting at with Tresco. It looks like CJF has added point work to allow for movements in the model that probably wouldn’t ever have happened in the real world and it’s not clear to me why you’d want to do them in the model. Removing some of it might help with some of your length problems.

 

You might like to have a look at Plymouth (North Road) pre-rationalisation, which also has a centre road between the main platforms forming a very long trailing crossover.

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I don't know of any instance where a bi directional centre road was used for non stopping trains to overtake stopping trains, plenty of centre roads which were available for one direction but not the other.  Usually a centre road was used as a siding (Bath) and had only trailing connections to both main lines.   The signalling and interlocking would have been very complicated for through running in both directions and the  Board of trade would probably have said a definite NO.  Just too much scope for a head on crash. The concept of three lines, up, down and express lines seems to have come from Rev Awdrey's illustrator.    There is no reason at all why track layouts have to be symmetrical with equal facilities in both directions.  On the GWR even the train services were not necessarily symmetrical with more trains in one direction than the other, the return being via another route.

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9 hours ago, Lichfeldian said:

I must admit that trap points issue hadn't occurred to me and although Peco do produce them, I don't recall seeing them commonly fitted in model layouts, perhaps for reasons of space. Not being familiar with "real" railway practice, I don't know what a "wide to gauge" trap would look like.

 

In "real" railway practise a trap point is installed such that it will deflect a vehicle away from the line that it is intended to protect.  In the majority of cases that will probably be into the cess on the left side.  The trap point could be a single switch blade like the type Peco produce, but it could also be two switchblades (ie half a standard turnout) or a full turnout, sometimes even with a buffer stop or sand drag.  In many locations a separate trap point isn't required if another turnout that say provides access to a head-shunt provides the same protection.  I believe this is known as 'flank protection'.

 

However, the situation you describe here is one where you don't want to deflect a vehicle to either the left or the right because the trap point needs to protect the lines running either side.  This therefore requires a "wide to gauge" trap point, which has two switchblades that move in opposite directions, so that the vehicle will derail in a straight direction.  You'd have to build this yourself as I don't think there is a ready to lay version on the market - certainly not in the Peco catalogue.

 

As for why trap points are often omitted from model railways, I suspect that it's a combination of  the fact that many train set modellers simply don't care too much about prototypical accuracy, a lack of knowledge regarding where they would be required, coupled with the fact that they take up space and cost money for little perceived benefit.  However, if you are aiming for prototypical fidelity, then they should be represented.  All of our club layouts have non-working representations of catch points.

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9 hours ago, Lichfeldian said:

Thanks for the responses. In reply to The Stationmaster, I had already substituted a single slip for the double slip accessing the bay platforms to the right. Would this be OK on a through line? I have also deleted the turntable and used the exit to it and the coaling stage from the bay platforms as the start of a single track branch.

 

However, it is a tad disappointing to discover that the whole basis of the plan is non prototypical! I'd assumed that as it was produced by a railway modeller of significant note in his day, that it would be reasonably authentic. I must admit that trap points issue hadn't occurred to me and although Peco do produce them, I don't recall seeing them commonly fitted in model layouts, perhaps for reasons of space. Not being familiar with "real" railway practice, I don't know what a "wide to gauge" trap would look like.

 

I had rather liked the plan as being a bit different and I'm reluctant to start yet again on another plan. I could easily replace the three way point with the successive right and left points, as on the original plan, although they would still be facing points of course. I do know that the old railway companies tried to avoid them, but again this seems to something frequently seen on model layouts. Otherwise, how could platform loops be laid out? What other alterations could do to make it more prototypical? What other use could the centre road have? 

The single slip is perfectly acceptable as long as it has a trailing end in the through line  (in other words it works like a diamond crossing for a train from the opposite line to access the bay and like a trailing crossover for a train from the bay to join the iine on which it will depart from the station towards the right.  Facing single slips could be found on running lines but they weren't common and tended to be mainly in low speed situations but trailing single slips were widely used in Britain.

 

The problem with CJF was that he designed model railway layouts with some very good designs plus occasional brilliant ones but sometimes the geometry didn't work - as you have found out - and often there was limited respect of railway operation in the real world, as with this centre loop.  Actually centre lines were not necessarily unusual including this triple line arrangement but inevitably they were either a siding accessed by trailing points at each end (a particular feature of many medium - larger GWR stations as well as the GCR) or they were a through line used in one direction only by passenger trains to overtake other trains and occasionally also used by freight trains for the same reason.

 

Trap points are, i think, omitted by many modellers because they simply don't understand why they would be needed.  And the reason for that lack of understanding is down to lack of knowledge about the real railway. (Although trap points there are far less common than they once were due to changes in traffic patterns and layout simplification.)

 

As I said I still think the original plan has some legs and could be adapted to a more prototypical arrangement if that is what you want to achieve.  You have a particular part of the country in mind, always a good start so you could research online to see how the basic CJF plan could be adapted to look a lot more like the way things were done in that part of the real world.  The site linked below has small scale copy diagrams of real signal box diagrams and while they don'y show sidings they will show connections to them.  They don't show every signal box on a particular route or area but they can help you to get a feel for the way various Companies and the LNER did things -

 

https://www.s-r-s.org.uk/html/lnerdiagrams.htm

 

You can of course also buy books but that can present budget problems and it is not easy to know exactly what to buy but good illustrated books showing the period you wish to model can be helpful.  It all depends on how far you wish to take your research as opposed to actually getting on with building your layout but I would always recommend researching the real world if you want your layout to look like the real world.

 

Your big decision is really what you want to do with that middle line.   What strikes me as a valid approach is to use it as a bypass line for trains coming from the left end of the station because in the opposite direction there are two platform faces so you in effect have an overtaking facility.  What I would also do is remove that awkward connection at the left end from the middle line to the lowe, loop, platform line but keep the trailing crossover to the middle line.  That will also solve the big track geometry problem in the plan.

 

The right had end is a bit more awkward because of the position of the curve but carrying on the theme at the other end I would remove what an mounts to a facing connection between the middle line and the line coming in from the right.  Ideally the middle line should have the best path towards the line departing at that end but that would mean a lot of changes so you might have to accept the compromise - it's noy the end of the world or you could retain the middle line as a purely good loops and provide proper trapping with a sand drag (which would shorten it a bit).  You've already reduced to a single slip so no change there - the arrangement you are left with to/from the bay is not very common but it definitely existed in some places so you have a reason for it.  The double slip in the looped platform approach is acceptable because speeds would be low.  I would do away with the odd sidings with a pit at that end - we've killed its purpose by altering the layout at the other end.  If you took out the middle siding you could avoid the double slip but that is up to you - either way it is justifiable as it givesa siding 2 feet long )once teh trap point is added which could stable two coaches or a station pilot etc.

 

That then leaves the big omission at that end - no trailing crossover - and it would have to be on the curve.  In my opinion adding it is an essential need that will give all sorts of extra working facilities.  Ideally you could do the same at the other end and move the trailing crossover onto the curve so it is between the two main lines.

 

I hope that helps a bit but don't be afraid to develop your own ideas around what could be done while keeping the basic idea of the layout plan because it does have some good points.

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OK - having digested the various postings, it is clear that the original CJF plan does not have much fidelity to prototypical railway practice, although I think it would look attractive in model terms. Even without much knowledge of real railway operations, I can see the potential for head-on collisions on the centre road is an obvious risk and therefore would be a problem on safety grounds. I'd assumed that signalling systems would be in place to prevent it, but on reflection, I suppose human error by drivers or signalmen could overcome these since, in the steam era, there was no ATC system except on the GWR. Thank you Stationmaster for the obvious amount of though you have put in, which you posted while I was in the middle of typing this. I don't quite follow everything you say about the revised layout of the points without having the layout in front of me, but I will give it some further thought. I can't upload a plan as I haven't got one - I have been mocking up the layout on the base board with the track sections I have already, and Peco's paper templates for the rest. If I can draw it out on paper, I will try and upload.

 

I will definitely change the middle road to the main through line, but I was thinking right to left, retaining the point and single slip into the upper bay platforms as a link from the main line to the bays and the branch that I have added where the sidings previously accessed the turntable and coaling point. The lower of the three centre roads will then just become a platform loop for stopping trains, with a trailing exit back out on to the middle road. Although this platform is effectively an island, I hadn't intended the lower face of it to be an operating platform - I was thinking of these two lower loops as being part of the goods facilities. I will also add some trap points, if I can. I've now found a picture on line of a wide-to-gauge trap and while I don't think anyone makes one, it might be possible to build a non-working thing that would sort of look the part. I think what I will end up with is a layout that won't be properly prototypical, but not as glaringly wrong as the original version.

 

Although the trains are 1930s LNER, this is just because they appeal to me and I am not trying to replicate any particular location or actual LNER operating practice. Regards.

 

Lichfeldian

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5 hours ago, DavidCBroad said:

I don't know of any instance where a bi directional centre road was used for non stopping trains to overtake stopping trains, plenty of centre roads which were available for one direction but not the other.  Usually a centre road was used as a siding (Bath) and had only trailing connections to both main lines.   The signalling and interlocking would have been very complicated for through running in both directions and the  Board of trade would probably have said a definite NO.  Just too much scope for a head on crash. [...]

I suspect that the bi-directional road is acceptably safe if both ends are controlled from the same box; the locking should make it so. However, if there is a box at each end of the station, then it's harder to see how safety is assured.

 

I could imagine a station with a line that is a running line in one direction only but which allows shunting movements in the other.

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14 hours ago, Lichfeldian said:

Thanks for the responses. In reply to The Stationmaster, I had already substituted a single slip for the double slip accessing the bay platforms to the right. Would this be OK on a through line? I have also deleted the turntable and used the exit to it and the coaling stage from the bay platforms as the start of a single track branch.

 

However, it is a tad disappointing to discover that the whole basis of the plan is non prototypical! I'd assumed that as it was produced by a railway modeller of significant note in his day, that it would be reasonably authentic. I must admit that trap points issue hadn't occurred to me and although Peco do produce them, I don't recall seeing them commonly fitted in model layouts, perhaps for reasons of space. Not being familiar with "real" railway practice, I don't know what a "wide to gauge" trap would look like.

 

I had rather liked the plan as being a bit different and I'm reluctant to start yet again on another plan. I could easily replace the three way point with the successive right and left points, as on the original plan, although they would still be facing points of course. I do know that the old railway companies tried to avoid them, but again this seems to something frequently seen on model layouts. Otherwise, how could platform loops be laid out? What other alterations could do to make it more prototypical? What other use could the centre road have? 

Don't dismiss out of hand the reversible centre track. Here in Melbourne Australia, we have an example with a significant length of run between multiple stations.

 

https://www.victorianrailways.net/signaling/completedia/erauburn2005.html

 

The centre track is reversible and is used for express trains (strictly speaking, limited stop as the trains run no faster) in peak hour. During off peak, generally the centre track and the northernmost line is used for normal services.

 

 

https://www.victorianrailways.net/signaling/completedia/erecam1981.html

 

Note how the 4 track main line becomes 3 at Burnley.

 

 

For good measure, here is an example of a junction station (Ringwood), where double track used to split to two single tracks. It also has a reversible centre line for you. Goods trains used to wait in the centre for a clear path.

https://www.victorianrailways.net/signaling/completedia/blackring.html

https://www.victorianrailways.net/signaling/completedia/blaringdia.html

 

Note catch points shown in the 1973 plan, but not the earlier one.

 

This station has recently been rebuilt and the signal box, is currently almost where it was in the earlier plan. But it is not used for railway purposes, but a cafe.

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31 minutes ago, kevinlms said:

Don't dismiss out of hand the reversible centre track. Here in Melbourne Australia, we have an example with a significant length of run between multiple stations.

 

https://www.victorianrailways.net/signaling/completedia/erauburn2005.html

 

The centre track is reversible and is used for express trains (strictly speaking, limited stop as the trains run no faster) in peak hour. During off peak, generally the centre track and the northernmost line is used for normal services.

 

 

https://www.victorianrailways.net/signaling/completedia/erecam1981.html

 

Note how the 4 track main line becomes 3 at Burnley.

 

 

For good measure, here is an example of a junction station (Ringwood), where double track used to split to two single tracks. It also has a reversible centre line for you. Goods trains used to wait in the centre for a clear path.

https://www.victorianrailways.net/signaling/completedia/blackring.html

https://www.victorianrailways.net/signaling/completedia/blaringdia.html

 

Note catch points shown in the 1973 plan, but not the earlier one.

 

This station has recently been rebuilt and the signal box, is currently almost where it was in the earlier plan. But it is not used for railway purposes, but a cafe.

I would guess, but I might be completely wrong, that the frequency of trains here might not be very high? They have similar things on the CPR and other American east West lines where huge trains run infrequently and are often stored on bidirectional centre lines.

 

I think Freezer had an approach more like a Meccano planner. Here we have a box of bits, how many different ways can they be put together in a certain space. Thinking well, this is a toy, but adults will use it and many will treat it as anything but.

 

I think the possibility of a head on crash on a model layout to be quite entertaining. Since I am DC its hard to organise, but I would have thought guys running DCC layouts would be able to set it up no problem.  A way to use up dodgy split chassis models

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4 minutes ago, RobinofLoxley said:

I would guess, but I might be completely wrong, that the frequency of trains here might not be very high? They have similar things on the CPR and other American east West lines where huge trains run infrequently and are often stored on bidirectional centre lines.

 

 

Yes, you would be wrong! This section is a busy commuter line and has off peak services of 15 minutes or so each way and much better than that in peaks. Trains are single deck, 6 car electrics, on 1500 Volts DC overhead. There is no freight service.

 

Here is one half of the timetable for this section.

https://www.ptv.vic.gov.au/route/timetable/9/lilydale/

There are currently service restrictions (Covid-19). There is also the Belgrave line, that also uses this section of track, running an equivalent service - so twice as many trains.

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Another possibility for a trap where there is limited space each side, is to fit a normal pair of trap blades, but fit a guard rail in the 4' so derailed vehicles are kept reasonably straight.

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4 hours ago, Lichfeldian said:

OK - having digested the various postings, it is clear that the original CJF plan does not have much fidelity to prototypical railway practice, although I think it would look attractive in model terms. Even without much knowledge of real railway operations, I can see the potential for head-on collisions on the centre road is an obvious risk and therefore would be a problem on safety grounds. I'd assumed that signalling systems would be in place to prevent it, but on reflection, I suppose human error by drivers or signalmen could overcome these since, in the steam era, there was no ATC system except on the GWR. Thank you Stationmaster for the obvious amount of though you have put in, which you posted while I was in the middle of typing this. I don't quite follow everything you say about the revised layout of the points without having the layout in front of me, but I will give it some further thought. I can't upload a plan as I haven't got one - I have been mocking up the layout on the base board with the track sections I have already, and Peco's paper templates for the rest. If I can draw it out on paper, I will try and upload.

 

I will definitely change the middle road to the main through line, but I was thinking right to left, retaining the point and single slip into the upper bay platforms as a link from the main line to the bays and the branch that I have added where the sidings previously accessed the turntable and coaling point. The lower of the three centre roads will then just become a platform loop for stopping trains, with a trailing exit back out on to the middle road. Although this platform is effectively an island, I hadn't intended the lower face of it to be an operating platform - I was thinking of these two lower loops as being part of the goods facilities. I will also add some trap points, if I can. I've now found a picture on line of a wide-to-gauge trap and while I don't think anyone makes one, it might be possible to build a non-working thing that would sort of look the part. I think what I will end up with is a layout that won't be properly prototypical, but not as glaringly wrong as the original version.

 

Although the trains are 1930s LNER, this is just because they appeal to me and I am not trying to replicate any particular location or actual LNER operating practice. Regards.

 

Lichfeldian

Making the middle line running from right to left only would be a much simpler change (and prototypical as it happens).

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