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Theory of General Minories


Mike W2
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Sorry, can't get my head round that one. Surely with a curved point, whether it is left handed or right handed depends on which way the point curves when approached from the tiebar end (i.e. the larger radius is equivalent to the "straight" and the sharper radius is equivalent to the "branch" on a straight point).

This is true from a commercial turnout viewpoint as Martin said, but not for the real thing. Think about it this way, if the crossover was straight then you would have no problem with it being made up from two left hand turnouts, curving the whole formation does not change this.  It is when you get to the fine detail that the distinction between left and right hand is defined. For the switches the divergent stock rail, left hand in this case would have a set to match the planing of the switch to keep the alignment of the main road correct. Then with a traditional built up crossing, the point rail should be in the main road and the splice rail in the diverging track. These two items effectively define the hand of the turnout irrespective of curvature. If you produvce a curved turnout in Templot then use the command to swap the hand you will see the difference.

Keith

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If the turnout at top-right was changed to a right-hand turnout, traffic on the running line would see the switch deflection angle and be subject to a speed limit.

True in theory, but at the turnout sizes under discussion the curvature and lack of cant means that the main road will have a speed limit and most likely at least as severe as that through the divergence. (but usually one of our modelling compromises is to consider curves to be of a much larger radius than we actually make them).

Keith

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As a p.s. to my previous post, often the curving radius in the main roads is more gentle. In which case contraflexure produces a Y-turnout effect, rather than an apparent change of hand. Here is such a crossover. Both of these turnouts are left-hand, just as they would be if the main lines were straight, and would still be if the main lines were more sharply curved:

 

800px-Filton_Abbey_Wood92.jpg

linked from: http://bristol-rail.co.uk/wiki/File:Filton_Abbey_Wood92.jpg

 

Martin.

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True in theory, but at the turnout sizes under discussion the curvature and lack of cant means that the main road will have a speed limit and most likely at least as severe as that through the divergence.

 

That's true Keith, but I was asked to explain the principle. You can't have true concentric curves through the running lines of a curved crossover unless both turnouts are of the same hand. Which means the inner turnout will have contraflexure. And no such turnouts are available from Peco (or any other manufacturer as far as I know).

 

Whereas for handbuilding a single click in Templot produces exactly what is wanted. But that's only any use if users know it's what they want. John said he was planning to use handbuilt track for his Minories plan.

 

regards,

 

Martin.

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Has anyone ever managed to build an N gauge minories? I'm thinking 8ft including fiddle yard would be sufficient in N.

I haven't seen one although 8'x1' sounds ample for N gauge. I have done a lot of drawings for minories-based layouts but they keep growing into more mainline stations. ;)

 

Thanks for that, is there a way to compress the turnout size.

If you are willing to tinker with the throat slightly and introduce slips (something not available RTR when CJF did the original), you can compress the throat further. Iain Rice did this with his "Harestone" track plan. It is a nice-looking plan but it is starting to lose the flavour of the original. Still, all food for thought.

 

http://i71.photobucket.com/albums/i157/janequeen/minoroesrice_0003.jpg

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 Iain Rice did this with his "Harestone" track plan. It is a nice-looking plan but it is starting to lose the flavour of the original.

 

I can't lay my hands on Finescale in Small Spaces just now, but as I recall, Iain Rice did not intend this plan to be a version of Minories itself, but rather the outer suburban complement, a different station altogether.  As a result the arrangement of points and slips is distinctly different too.

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Hi Ian,

 

The hand of a turnout is determined by the hand of the switch. The direction of curving through the turnout is irrelevant. It is an important distinction because it controls the speed limits through the turnout.

 

The hand of a switch means the direction of the switch deflection angle. This is a left-hand switch:

 

stock_rail_rea.jpg

 

Traffic traversing the main road straight ahead sees no deflection and can proceed at full line speed.

 

Traffic traversing the diverging turnout road to the left is suddenly deflected from its path at the switch deflection angle. In a B-switch that angle is 1:32. In a C-switch it is 1:40.

 

You can see the switch deflection angle as a sharp bend in the left-hand stock rail, called the "set". The planing of the switch blades matches the same angle.

 

Because of the switch deflection, there is always a speed limit for traffic traversing the diverging road of a turnout, sometimes a severe limit.

 

Crossovers between running lines are always arranged so that the switch deflection is towards the crossover road, so that there is no speed restriction for traffic on the running lines. This means that both turnouts in such a crossover are always of the same hand.

 

Here below you can see that for the straight track, both turnouts are obviously left-hand. When the whole formation is laid into a curved track, the turnouts don't change. They are both still left hand:

 

attachicon.gifall_lh_turnouts.png

 

When the curving through a turnout goes in the opposite direction from the hand, as in the top-right turnout, it is called "contraflexure". In Templot the curving radius in the main road is shown as a negative value for contraflexure.

 

If the turnout at top-right was changed to a right-hand turnout, traffic on the running line would see the switch deflection angle and be subject to a speed limit.

 

regards,

 

Martin.

Hi Martin,

 

Thank you for the explanation .................. I think I've got it now! I'm constantly being amazed at what I don't know, you tend to just assume "it's like that!" and it's wrong, I am very grateful for your willingness to share information, thank you. What it also does is reinforces my opinion of what a superb piece of software Templot is, well done.

 

Regards

Ian

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A proper double-track crossover always has both turnouts of the same hand, even when in curved track. This is impossible to create using Peco curved turnouts (or any other ready-made track that I know of).

 

The Peco exit angle of 12 degrees (1:4.7) is far too sharp for passenger trains, the normal limit being 1:8 for straight crossovers and then only dead slow.

 

Curved crossovers can be created without a reverse curve, but still need a long crossing angle to keep the radius sensible. A good size for model curved crossovers is C-10. Here's a print from Templot showing that:

 

attachicon.gif00_bf_c_10_750mm.png

 

edit: the inner turnout (but not the outer) could be changed to a B-10, saving a bit on the overall length.

 

regards,

 

Martin.

Thanks Martin. That is useful. Clearly most of us will always be compromised on length so anything that enables the effects of unprototypically short pointwork to be mitigated is worthwhile. Is the situation for crossovers on curves different in throat pointwork, particularly for termini where all traffic is speed restricted? 

 

You've also mentioned that 1:8 would be the normal minimum crossing angle for crossovers used by passenger trains  but would the minimum for non-crossover pointwork be smaller? I do know of one example (not in the UK) where an entire passenger station throat was laid with standard left and right handed turnouts with crossing angles of 1:7.6 but with no reverse curves though that does seem to have been exceptional. 

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I can't lay my hands on Finescale in Small Spaces just now, but as I recall, Iain Rice did not intend this plan to be a version of Minories itself, but rather the outer suburban complement, a different station altogether.  As a result the arrangement of points and slips is distinctly different too.

You're quite right. Harestone is also in his Designs for Urban Layouts in a chapter described as "Majoring on Minories" and I'm looking at it now. It's an interesting plan but though Ian Rice describes it as "my take on Minories" it really has little in common with Cyril Freezer's classic design. Harestone is an outer suburban terminus with a single island platform inspired by Caterham. The only things it does have in common with Minories is its small size (6ft6ins by 15ins) its handling of short suburban trains off a double track line and a high level station building in low relief at the terminus end.   

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Martin

 

Thanks for that, is there a way to compress the turnout size. No doubt there is room for the crossover but there will be a big gulf in size between them and the nine foot V5 turnouts 

 

Are the 50mm track centres OK with 30" curves please

 

Hi John,

 

Yes, 50mm centres is the 00-BF standard, similar to Peco and good down to 24" radius or maybe a bit smaller.

 

For the crossover size everything depends on your acceptable minimum radius in the outer turnout? Toy trains traditionally go down to 15" radius but unless you will be running only old toy trains I don't think you can sensibly go that sharp. Perhaps a suitable absolute minimum would be 450mm / 18" radius?

 

To get the easiest possible radius in the shortest turnout you need to select the non-prototype model switches in the list, and a generic type V-crossing.

 

2_011146_480000000.png

 

 

Using the shortest 1:24 model switch and generic 1:6 V-crossing you can get this crossover:

 

2_011147_280000000.png

 

750mm radius in the outer double-track and 700mm in the inner double track. Generic V-crossings. The turnout radius in the outer turnout is just over the 18" limit at 464mm / 18.3".

 

These are both Right-Hand turnouts.

 

This seems to be about as tight as you can sensibly go with kit-built models, and even then is likely to mean carving lumps out of them for loco bogies to swing, carving behind splashers for extra side-play on wheels, wires across the buffers to prevent locking, etc.

 

Against that the big advantage of putting the crossover on a curve is that there is no reverse curve to cause problems.

 

regards,

 

Martin.

Edited by martin_wynne
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  • 4 months later...

I have a question about the Minories style of layout.

 

There are basically two lines in and out of the station

 

If I understand it properly the idea is that a train could arrive and leave at / from any platform

 

My question is ...

 

As a train clears the throat when it leaves the station, should it aways exit on the correct 'up' line

 

Or - is there a definate in line and a definite out line ?

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It would depend to some extent on what you are trying to model. You run both lines bi-directionally with the appropriate signalling if you so wished. I would normally keep is simple and have the trains driving on the left once beyond the station throat.

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I have a question about the Minories style of layout.

 

There are basically two lines in and out of the station

 

If I understand it properly the idea is that a train could arrive and leave at / from any platform

 

My question is ...

 

As a train clears the throat when it leaves the station, should it aways exit on the correct 'up' line

 

Or - is there a definate in line and a definite out line ?

I think you would normally only use bi-directional working on a fairly busy line or to enable trains to overtake each other on a double track line but at a terminus what goes up must come down and if it's busy, especially with a limited number of platforms, there has to be a balance of trains arriving and departing or else it would get very empty or very crowded very rapidly.

It really depends on where you consider the end of the throat to be. In practice you'd connect each platform to both up and down lines but you might well have one or more additional crossovers a little way down the line to allow various shunting moves such as moving empty stock in and out of adjoining carriage siding or light engine moves to take place wihout creating a conflict. 

 

The major difference between our designs and most prototype ones is that the big railway usually has plenty of length to play with so can have fairly extended station throats. What also normally happens at busier termini is that there are several additional routes between each platform and each of the main line tracks so that simultaneous arrivals and departures can take place between any two platform roads. This involves extra parallel track and a number of crossovers before you reach the final up and down lines. Where the approach to a terminus is constrained by a tunnel or a narrow viaduct you can though get some very elegant solutions to this problem.

 

This very sketchy example may illustrate the principle.

 

The first plan is operationally the same as Minories but straightened out. As with Cyril Freezer's design there are only four points lengths from the end of the platforms to the end of the throat. This is simple and compact and I think Windsor Riverside followed this arrangement when it had three platform faces. The limitation is that you can't have a simultaneous arrival and departure from platforms two and three and a light engine move to or from platform two also blocks platform three .

post-6882-0-62836100-1428019375_thumb.jpg

The second plan is a slight development.and now the extra track between platform 3 and the up main line allows for simultaneous arrivals and departures with any two platforms and also means that a light engine move to or from the loco spur can take place with less chance of conflicting with a train movement .

post-6882-0-63868900-1428021033_thumb.jpg

Finally I've also added a couple of carriage sidings that can be accessed from any of the three platforms and by extending the throat with a second trailing crossover far more movements are possible. for example a train can be shunted in or out of the sidings while a train is simultaneously arriving or departing from a higher numbered platform and a loco that has just propelled a train into the sidings can make its way to the loco spur while trains are  arriving or departing from any of the three platforms.

post-6882-0-63632200-1428019381_thumb.jpg

Minories itself is operationally equivalent to the first plan but it was the particular arrangement of points that made Cyril Freezer's design such a classic as it avoids several immediate reverse curves over crossovers.

post-6882-0-99979500-1428022504_thumb.jpg

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Hi David

 

Thanks for the reply - that really is very useful and interesting - a great explanation.

 

Your version with the carriage sidings is especially interesting to me.

 

Could you explain how you imagine steam hauled trains would work please

 

I understand that the arriving train would see the loco trapped - and after the passengers are all off it could propel its coaches into those carriage sidings - but how do you get a loco at the other end ?

 

I assume you have to have a second loco arriving light ( tender first ) to come and take that train away - would this move see the original loco trapped at the end of the platform at the buffer stop assuming it waited and pulled it back out of the sidings ? - I assume this would then leave light to turn somewhere down the line to return light and take another set away ?

 

Ps - I am imagining myself a version without a loco spur but am interested in the operation both with and without a spur.

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The loco spur could be off the scenic section, certainly at Euston the empty coaches were propelled into the carriage sidings for cleaning. Not too certain about steam hauled surburban services, perhaps a light engine in another platform would be used to haul the next service out

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Hi David

Thanks for the reply - that really is very useful and interesting - a great explanation.

Your version with the carriage sidings is especially interesting to me.

Could you explain how you imagine steam hauled trains would work please

I understand that the arriving train would see the loco trapped - and after the passengers are all off it could propel its coaches into those carriage sidings - but how do you get a loco at the other end ?

I assume you have to have a second loco arriving light ( tender first ) to come and take that train away - would this move see the original loco trapped at the end of the platform at the buffer stop assuming it waited and pulled it back out of the sidings ? - I assume this would then leave light to turn somewhere down the line to return light and take another set away ?

Ps - I am imagining myself a version without a loco spur but am interested in the operation both with and without a spur.

If you're not already au fait with it, search on here or YouTube for Bradfield Gloucester Square, similar in principle and operated using prototype practice's.

 

Darned autocorrect, it's practices - there is no need for the unnecessary apostrophe, a pet hate of mine.

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If one is really looking to save space, there are prototypes that justify both tracks being used bi-directionally. Glasgow Queen St is one (two versions on RMWeb), Lyon St Paul is another - where the crossovers are a short way into the tunnel.

Trouble is that it does not make for such an interesting model to operate. Much better to have the crossovers in view even if you have to cheat a bit on something else.

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Hi David

 

Thanks for the reply - that really is very useful and interesting - a great explanation.

 

Your version with the carriage sidings is especially interesting to me.

 

Could you explain how you imagine steam hauled trains would work please

 

I understand that the arriving train would see the loco trapped - and after the passengers are all off it could propel its coaches into those carriage sidings - but how do you get a loco at the other end ?

 

I assume you have to have a second loco arriving light ( tender first ) to come and take that train away - would this move see the original loco trapped at the end of the platform at the buffer stop assuming it waited and pulled it back out of the sidings ? - I assume this would then leave light to turn somewhere down the line to return light and take another set away ?

 

Ps - I am imagining myself a version without a loco spur but am interested in the operation both with and without a spur.

Hi

This wasn't intended to be a fully worked out plan but really just to illustrate the reasons why the approaches to a terminus are likely to stretch for some way down the line with various additional tracks until the main line finally settles into one or two pairs of up and down lines.

 

In reality, for loco hauled trains, the carriage sidings might well be double ended or with their own loop and headshunt. If you study real steam age track plans for even small main line termini (just Google terminus name and track plan and they usually appear) you'll see that they're generally vast with with half a mile or more of complex trackwork before you reach the plain up and down main lines. Today, with mutliple units and block goods trains dominating the scene, trackwork is far simpler but even so, if you explore the approach to any main line terminus on Google Earth (a really useful tool) you can see just how much pointwork there still is. The challenge for us is to represent those operations in a very limited space but fortunately this challenge was also faced at some real termini. 

 

This signalling diagram of Marylebone is particularly instructive http://www.signalbox.org/diagrams/marylebonestn1945.jpg  . John Hinson's signalbox site http://www.signalbox.org is a real goldmine if you want to find out what trackplans were really like and they were far more complex than most modellers imagine. If you go into the track layouts section I'd suggest looking at Lowestoft (1969 after Beeching and in GER days), Bournemouth West, Cheltenham St. James, Epsom Downs (1920) which all have relatively short approaches and compare those with the modern 2000 EMU trackplan of Littlehampton.  Just for fun, since some of us were there last weekend, Alexandra Palace in 1906 is worth a look.

 

I'm not sure in Britain how common it was for arriving train engines to dispose of their own coaches before going to the shed or turntable. Some stations did make a lot of use of pilot locomotives and at Paddington it used to be quite common (I know because I saw it a few times in the latter years of steam) for a train of carriages to be brought into the platform from the sidings where it had been serviced by a pannier tank that was then trapped at the platform head while the King or Castle or whatever turned up from Old Oak Common or Ranelagh Bridge, coupled up and then, once the passengers had boarded, took the train out. The pannier would then follow the train out to the platform end before being signalled for its next job. I say the pannier was trapped but in winter it may well have been supplying steam heating to the train until the train engine had coupled up.

 

With the simple arrangement I've suggested the train engine could dispose of its train to the sidings before going on shed and a station pilot could bring a new train onto the platform and remain there until the train's departure with a new train engine at its head. That would though slightly shorten the maximum length of train. In steam days it was also far more common for trains to be made up and broken, for extra carriages to be added or subtracted, for parcels and newspaper vans to need shunting even for sleeping cars to be switched between trains so the pilot could well be the busiest loco around.

Edited by Pacific231G
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If one is really looking to save space, there are prototypes that justify both tracks being used bi-directionally. Glasgow Queen St is one (two versions on RMWeb), Lyon St Paul is another - where the crossovers are a short way into the tunnel.

Trouble is that it does not make for such an interesting model to operate. Much better to have the crossovers in view even if you have to cheat a bit on something else.

Thanks Joseph;  Lyon St. Paul certainly is an interesting prototype because it also included local goods facilities and it was crammed into a very short space before a fairly long tunnel

This was it in 1933 with a lot of wagon turntables

post-6882-0-80758800-1428063106_thumb.jpg

and rather simplified in 1984

post-6882-0-43536600-1428063068.jpg

This is the rough trackplan (not to scale)

post-6882-0-34785100-1428064631.jpg

 

As Joseph says there is a scissors crossover just inside the tunnel mouth but though trains can enter or leave the tunnel on either line it is AFAIK signalled for normal up and down running and certainly was when it was mechanically signalled.

 

I visited the terminus not long before the goods shed was demolished but wasn't able to take many photos thanks to a very officious member of staff. There is though a fairly clear aerial image of the layout with the goods shed as it was in 2001 on Google Earth

 

St.Paul looks like almost every bit of modeller's licence in one place. It fronts onto a street where it is on arches with lock up garages but backs onto a sheer rock face, the whole station is improbably short just 230metres (In  H0 scale 2.6 metres or just over eight and a half feet) in a straight line between the tunnel mouth and the buffer stops, trains enter the 1400 metre long tunnel almost immediately after leaving the platform ends, the final scissors crossover inside the tunnel means that you could cheat and run straight into a fiddle yard and finally there used to be a funicular railway adjoining the station entrance.   

Edited by Pacific231G
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If one is really looking to save space, there are prototypes that justify both tracks being used bi-directionally. Glasgow Queen St is one (two versions on RMWeb), Lyon St Paul is another - where the crossovers are a short way into the tunnel.

Trouble is that it does not make for such an interesting model to operate. Much better to have the crossovers in view even if you have to cheat a bit on something else.

Add sunny Great Yarmouth to that list too, although technically that's 2 single track branches arriving side by side plus the carriage sidings line (3 potential lines in/out of the station, light engine moves, and a pilot). The carriage sidings there were used more for stock from Norwich so most appropriate era stock is justifiable even if it wouldn't really serve Yarmouth. The track plan breaks from the usual minories by being a mirror image of CJ's plan, has an extra platform face used, and having a single slip as part of the crossover from platform 2 to 3 (allowing platform 1 across to the line that goes into platform 3). The plan is very visable from google earth, I don't know but I suspect that when the carriage sidings were in use that platform 1 was used as a head shunt for them with platforms 2 and 3 serving the Acle and Reedham branches respectively. Platform 4 and the siding beside covered any additional requirements (the single siding alongside platform 4 and short head shunt (still there in the weeds) used to be the fan for the goods yard sidings before the whole area was turned into an Asda). Using that method of operation it would be feasible to leave off the crossover from platform 2 to the carriage sidings as 'hidden off scene' and space pending possibly ignore the 3 to 2 crossover as well. The joy of the location for the modeller is the very usefully placed road bridge over the station throat beside the signal box ;)

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  • 4 weeks later...

On the minories theme, my modelling companion was describing a plan yesterday that sounded very interesting. He thought he'd seen it in the BRM Track Plans special edition, but I can't find it. It was based on Minories but had a line going off before the terminus platforms to introduce through services not calling at the terminus station. He mentioned that they'd mocked up the plan to show that a 4CEP would fit along with a 2EPB. Can anyone shed any light on it please?

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On the minories theme, my modelling companion was describing a plan yesterday that sounded very interesting. He thought he'd seen it in the BRM Track Plans special edition, but I can't find it. It was based on Minories but had a line going off before the terminus platforms to introduce through services not calling at the terminus station. He mentioned that they'd mocked up the plan to show that a 4CEP would fit along with a 2EPB. Can anyone shed any light on it please?

 

 

WH Smiffs had some on sale last week

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Sorry Hayfield, what I meant was I couldn't find it in the track plan book. I bought a digital copy last night.

The plan you are looking for is "Manitoba Quays" which in the printed edition is on pages 86 to 92. Hope that helps you.

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