Track spacing for yards with R1 turnouts

[Andrew_au]

Consider a classic "yard ladder" layout, implemented using LGB R1 switches:


Two questions:

• what sort of clearance should I aim for between the tracks?
  • 2x R1 back-to-back gives 160mm centre to centre
  • a 300mm straight (as per the straight section on an LGB turnout) followed by an R1 curve gives 150mm
  • adding a 41mm spacer gives 170mm
• lots of example sidings end up with 2xR1 back to back (see the curved path through the two turnouts above). However, there's a general principle that opposing curved sections should be separated by straight sections. Is there a minimum length of straight that you would recommend between the two curves?

Observations on geometry​

Using basic 300mm straights, it is impossible to have a ladder layout with 160mm spacing and having the tracks all even at the end. PIKO works around this by avoiding 300mm straights and instead using 320mm + 280mm. Turnouts use a 320mm straight, which allows the vertical geometry to end up at exactly 160mm and the horizontal geometry to end up pretty close.

Consider the middle and lower paths through the ladder. If we start from the start of the first turnout using PIKO track, the horizontal lengths are:

• middle path: 300 + 300 + 280 = 880mm
  • 300 = 600 * sin(30)
• lower path: 300 + 277.1 + 300 = 877.1mm
  • 277.1 = 320 * cos(30)

Using PIKO track. Strictly speaking, each branch of the ladder is a couple of mm different, but that's very hard to notice. Confusingly, my track tool says that it is a perfect match, which makes me wonder if I've made a mistake in my maths somewhere.


Another image with LGB track showing how left/right pairs don't match up with angled straights

Using LGB track and cutting custom lengths, a 20mm spacer on the angled turnout (bringing total straight length to 320mm) would match the vertical spacing. Aligning on the horizontal would require an extra 22.87mm.

Requirements and implementation​

In practice, maintaining perfect 160mm spacing and horizontal alignment isn't required for yards which connect at only one end.

• Using a ladder of junctions paired with curves maintains neat alignment, but has two serious drawbacks:
  • requires a lot more horizontal space for the same number of yard branches (lose at least 300mm per branch)
  • avoiding lots of opposed curves requires adding spacers
    • spoils the neat alignment and spacing
    • adds extra horizontal cost to every branch
• Might need extra spacers
  • on first branch to avoid opposed curves
  • on remaining branches if 150mm separation is insufficient clearance
• Differences in alignment are relatively minor, and can be hidden by adjusting placement of buffer stops or other features
  • Visually, I don't mind if the "mainline" past the yard has a slightly different (wider?) spacing than the sidings.
• Using custom flex-track lengths avoids many of these issues

Alignment becomes more of an issue if using sectional track and trying to have turnout ladders on both ends, or especially if using asymmetric turnout layouts on each end.

 

[dunnyrail]

Spacing as defined by LGB sections is perfect. However on ladder and through yards (not on curves) it is possible to make tracks closer depending on stock used. I use LGB and Trainline German prototypes and in my fiddle yard have managed to cut the gap so that I can get 5 sidings where LGB geometry with R3 curves only gave me 4 sidings. Very useful if you have a lot of stock to store between sessions. However this would not work for Bachman Fn3 stock as it is much wider.

 

[JimmyB]

However this would not work for Bachman Fn3 stock as it is much wider.

I think this is the point (no pun intended), that track spacing is dependant on what you run on G45, a little like tunnel and bridge heights, a question that I asked about when starting out. I was use to a "loading gauge" that would define heights and widths, but as somebody told me unless you are only going to be running one make and one scale there is no standard.

 

[Rhinochugger]

Yes, and I think the other issue is to consider something larger than R1 unless you really have no alternative.

R1 will generally limit you to LGB or kit-built 4w rolling stock. In reality, it's a bit too tight.

R3 is a better place to start for those who have the necessary space.

 

[Gizzy]

Track spacing for LGB R1 to R2 and parallel tracks is actually 165mm.

For LGB R3 and above, it's 185mm.

PIKO track is different geometry; their R3 will fit inside LGB R3 if you want a double track curve....

 

[idlemarvel]

Ref your track planning tool saying it is a perfect fit, you will probably find it has some tolerance settings to allow you to join track that "almost fits".

 

[Andrew_au]

Spacing as defined by LGB sections is perfect.

By this do you mean "150mm spacing is plenty for most purposes"?

Yes, and I think the other issue is to consider something larger than R1 unless you really have no alternative.

R1 will generally limit you to LGB or kit-built 4w rolling stock. In reality, it's a bit too tight.

R3 is a better place to start for those who have the necessary space.

The yard is inside an LGB R1 loop. The R1 loop is constrained by the available space, but runs all my trains fine.

Using R3 junctions would reduce siding length by about half a metre (roughly the length of an LGB 16000 R3 curve) vs R1 sidings. This could be done, but I've got less than 2m as it is. R3 spacing is also wider (~180mm vs 160mm), but that's not an issue.

Admittedly, sticking spacers between the R1 turnouts increases both the width and length of the R1 ladder, but I could add 2x 150mm spacers (which seems excessive) to the R1 ladder and it would still be shorter (but wider) than the R3. If I do a larger yard in a more open area I'll probably go with R3 turnouts (or compromise and try the PIKO R3 turnouts, which are about half-way between R1 and LGB R3).

However, R3 turnouts still have an opposed curve, albeit a much softer one. At shunting speeds, are these opposed curves (R1 and/or R3) an issue? Is there any recommendation on how wide a spacer I should use to mitigate it?

Note - I'm not overly concerned about long wagons clipping other wagons while cutting the corners. In addition to the curves, there is another 150+mm of uncoupler tracks before I get to the parking area.

 

[Rhinochugger]

The general wisdom is that reverse curves are best avoided, usually achieved by inserting a small, straight section between the two curves, but that doesn't appear to be an issue in LGB catalogues / information.

As for shunting through R1 reverse curves, I don't know as I've never tried it, and here again, I suspect it depends on your rolling stock.

If you use entirely LGB stock, with couplings and buffers as provided, in theory you should be alright.

 

[Dan]

For a 3 way split and space issues I would use the LGB 3 way Y switch aqnd avoid at all costs a reverse curve without a straight section between curves.

 

[Greg Elmassian]

For a typical ladder, it's impossible to eliminate all reverse curves, there has to be at least one....

I'd space them as closely as you can to get the most storage. It depends on the max width of your cars, for example my track to track spacing in pretty close, with Aristo WR switches with no extra track between them. If I was running 1:20.3, I might need greater spacing.

This is not all finished, the switching leads are not on, but you can see that you can switch cars without fouling the main line (leftmost track)

 

[Henri]

This link provides useful information about the LGB track geometry:

https://www.lgb.de/fileadmin/media/lgb/service/FAQ/LGB-Technik-Tipp-201-LGB-gleissystem.pdf

 

[Andrew_au]

I'd space them as closely as you can to get the most storage. It depends on the max width of your cars, for example my track to track spacing in pretty close, with Aristo WR switches with no extra track between them. If I was running 1:20.3, I might need greater spacing.

I see two reverse curves - between the mainline and the yard entry, and between the 1st yard track and the 2nd. I hear you saying that you have no issues with these (with the caveat that the Aristo WR turnouts are approximately LGB R3 not R1)?

This is not all finished, the switching leads are not on, but you can see that you can switch cars without fouling the main line (leftmost track)

I notice your continuation track in the yard is fairly short. Does this matter? As far as I can tell, the number of cars you can switch at once is limited by how much space you have beyond the turnout.

This link provides useful information about the LGB track geometry:

https://www.lgb.de/fileadmin/media/lgb/service/FAQ/LGB-Technik-Tipp-201-LGB-gleissystem.pdf

That is actually quite useful (and a lot more so than the diagram at the back of their current brochure). Do you know if there's an English version?

 

[Rhinochugger]

I see two reverse curves - between the mainline and the yard entry, and between the 1st yard track and the 2nd. I hear you saying that you have no issues with these (with the caveat that the Aristo WR turnouts are approximately LGB R3 not R1)?

I notice your continuation track in the yard is fairly short. Does this matter? As far as I can tell, the number of cars you can switch at once is limited by how much space you have beyond the turnout.

That is actually quite useful (and a lot more so than the diagram at the back of their current brochure). Do you know if there's an English version?

The Aristo points are 10ft dia as opposed to R3s at just under 8ft dia (Aristocraft did an even shorter point, but I don't think Greg's using those).

 

[Greg Elmassian]

Andrew:

A reverse curve ("S" curve) consists of TWO curves ... one curve alone cannot "reverse"..... you need 2 curves in the opposite direction very close to each other...

Yes as stated in post #10 Aristo WR (Wide Radus) switches, 10 foot diameter switches that are curved throughout like LGB. Aristo did indeed make R1 switches.... nothing but trouble with USA prototypes. The yard shown will allow 80 foot prototypes, but you would switch them on the tracks to the further right to avoid S curve issues.

Also as noted in post #10 : the tracks for the "switching lead" are not in place in the picture... There are indeed TWO switching leads (not on the mainline) one at each end of the yard.

I would suggest reading this, a lot of information distilled into one page about the nomenclature for yards, and what a switching/yard lead is:

Designing a yard

Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers

elmassian.com

(picture of single-ended yard, my yard is double ended)

Greg

 

[Rhinochugger]

Andrew:

A reverse curve ("S" curve) consists of TWO curves ... one curve alone cannot "reverse"..... you need 2 curves in the opposite direction very close to each other...

Yes as stated in post #10 Aristo WR (Wide Radus) switches, 10 foot diameter switches that are curved throughout like LGB. Aristo did indeed make R1 switches.... nothing but trouble with USA prototypes. The yard shown will allow 80 foot prototypes, but you would switch them on the tracks to the further right to avoid S curve issues.

Also as noted in post #10 : the tracks for the "switching lead" are not in place in the picture... There are indeed TWO switching leads (not on the mainline) one at each end of the yard.

I would suggest reading this, a lot of information distilled into one page about the nomenclature for yards, and what a switching/yard lead is:

Designing a yard

Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers

elmassian.com

(picture of single-ended yard, my yard is double ended)

Greg

Well, I've learned something - the run-round loop for the caboose

 

[voodoopenguin]

Going back many years to an OO layout I did, I managed to ditch all reverse curves by having the yard angled to the line entering it. This also meant all rungs of the ladder were the same length. Please excuse the very rough drawing.





Paul

 

[Andrew_au]

A reverse curve ("S" curve) consists of TWO curves ... one curve alone cannot "reverse"..... you need 2 curves in the opposite direction very close to each other...

These are what you refer to as "reverse curves", right? If so, there are at least two.

I assume there is enough intervening track to not create a 3rd between the two highlighted turnouts.

S curve issues.

Is the canonical terminology "S curve" or "reverse curve"?

Also as noted in post #10 : the tracks for the "switching lead" are not in place in the picture...

Ah! I read "switching lead" and was confused - I was thinking "lead" as in "power feed" and not "track extension".

I would suggest reading this, a lot of information distilled into one page about the nomenclature for yards, and what a switching/yard lead is:

Thanks. That's quite helpful. Will need to make some compromises as I'm more interested in parking trains / parts of trains than a fully functional switching yard. I'd like a full yard at some point, but will need to find somewhere with more space.

(picture of single-ended yard, my yard is double ended)

In terms of yard operations, does the double-end fundamentally change things? I can see two immediate possibilities - speeding up assembly / disassembly by picking from both ends, or distributing cars from one end and picking from the other. But I don't know if these are realistic scenarios, or if the double ended yard is used in other ways.

 

[Greg Elmassian]

Ahh, lots of questions and lots of answers..

The crossover is from the main line to the yard lead.... the leftmost track is not in the yard... there is indeed an "S" curve in that crossover, as with any crossover... those my son, are #6 switches which is somewhere around a 14' diameter or larger, not directly comparable, but you enter the yard by that crossover... with #6 switches you can easily use 80 foot cars...

yes, there is no room between the 2 circled turnouts and none is needed.

you bring the train through the crossover and then leave it on that track to be broken down, if you enter, you would cut the locos off and run around (double ended yard)

"S curve or reverse curve" is fine... I think S curve is more common in the US, and it is a better description, when the train is on it, it forms an S (or a reverse S)..

switching lead or yard lead are the common terms.... the "tail" the train can run into to clear switches to pick a different track.

a double ended yard has many advantages, first you have 2 switching leads, one at each end. Also any ladder track can be used as a runaround (where the loco can run around the train and go to the other end of the train)

In prototypes, you can have 2 engineers making up 2 trains at once instead of just one.

The mainline here can have trains coming into it from either direction, so a double-ended yard makes things easier.

Again you cannot see both yard leads, the near one parallels the wye track on the right and the far one goes straight away from you.

below is the full track plan: (before I moved the yard closer to the house)

 

[Rhinochugger]

The #6 turnouts are indeed things of beauty - but are about 3ft long, so take up a lot of space, but well worth it if you have the space.

Trains run through them smoothly and easily

 

[Eeyore.Boater]

Is a switching lead or yard lead the same as the British headshunt?