Points Spacing

[rab]

I've been doing a bit of track planning for my layout

which might get built one of these days!!

 

I have a situation where ideally I need

2 turnouts next to each other, but I seem

to remember reading somewhere that this can

cause problems, (derailments etc.).

 

Is this correct, is it better to have

a section of plain track between turnouts?

[Theheretic]

Hello Brian,

 

A track plan would be useful to see what you are planning and how the two turnouts are situated in the overall scheme of things.

 

PS: I had a look at your registration page and noted your comment the you are "planning to build a layout when life stops getting in the way"

 

I think John Lennon's comment is apt here: "life is what happens while we are busy making plans"

 

I think the message is "just get on with it in spit of ........."

 

Best regards,

 

Pierre

 

 

[Joseph_Pestell]

As Pierre says, it rather depends what is going to be running where. If some movements are going to result in the train taking a reverse (S) curve, there is a risk of buffer locking and derailments, especially when propelling.

[34theletterbetweenB&D]

I would encourage the thought that what others can tell you in this matter is a direct reflection of their own choices and workmanship. None of that is completely relevant, because it is the combination of the track layout you want, to the construction standard you can achieve, with the stock you choose to run, operated to whatever standard you require, that is actually going to happen.

 

I determined by experiment the track standard required for my operation (OO, 30" minimum radius plain track, Peco streamline large and medium radius points and kit points of 36"+ radius) which may be both arranged and operated over with no restrictions) and would urge you to do the same.

[Chimer]

It's hard for me to envisage any sort of layout (other than a diorama) that doesn't feature a crossover somewhere, and a crossover requires 2 turnouts next to one another and (usually) a reverse curve.  Also you're likely to want some sidings somewhere which need a fan of points which can't be separated by much without looking rather strange.  I'd just bite the bullet if I were you ….

 

Chris

[Siberian Snooper]

If you mean two turnouts at a double Junction, then the turnout that forms the inner radius is slightly infront of the turnout that forms the outer radius by a couple of cribs.

[DCB]

I would encourage the thought that what others can tell you in this matter is a direct reflection of their own choices and workmanship. None of that is completely relevant, because it is the combination of the track layout you want, to the construction standard you can achieve, with the stock you choose to run, operated to whatever standard you require, that is actually going to happen.

 

I determined by experiment the track standard required for my operation (OO, 30" minimum radius plain track, Peco streamline large and medium radius points and kit points of 36"+ radius) which may be both arranged and operated over with no restrictions) and would urge you to do the same.

It also depends a lot on the baseboard construction but I would strongly advise against short lengths of plain track between points, Our terminus station is plagued with these little bits of track intended to keep the point operating bits away from adjacent tracks but they never ever stay straight or level and cause all sorts of derailments where couplings ride over each other.  I have tried to eradicate them by replacing short radius points with long ones but its a long job.  There is an additional benefit in that the less fishplates the less droppers you need .

 

 My tracks are 00 code 100 3rd radius minimum plain track and 2ft nominal minimum radius points and I can't run long wheelbase 4 wheel stock longer than Wrenn GWR Fruit Ds but I can reverse 30 wagon trains over reverse curves over 2ft points.   I find it beneficial to shorten the points at the frog end rather than add bits of rail between them to smooth out any possible reverse curves, I carve sleeper ends off adjacent racks, carve bits off tie bars and generally butcher points to fit the space available. Points across baseboard joins and baseboard surface joins are generally a recipe for problems but a short bit of plain track across a join will give every bit as much hassle, I use a long bit,150mm and let it float.

[rab]

It also depends a lot on the baseboard construction but I would strongly advise against short lengths of plain track between points, Our terminus station is plagued with these little bits of track intended to keep the point operating bits away from adjacent tracks but they never ever stay straight or level and cause all sorts of derailments where couplings ride over each other.  I have tried to eradicate them by replacing short radius points with long ones but its a long job.  There is an additional benefit in that the less fishplates the less droppers you need .

 

 My tracks are 00 code 100 3rd radius minimum plain track and 2ft nominal minimum radius points and I can't run long wheelbase 4 wheel stock longer than Wrenn GWR Fruit Ds but I can reverse 30 wagon trains over reverse curves over 2ft points.   I find it beneficial to shorten the points at the frog end rather than add bits of rail between them to smooth out any possible reverse curves, I carve sleeper ends off adjacent racks, carve bits off tie bars and generally butcher points to fit the space available. Points across baseboard joins and baseboard surface joins are generally a recipe for problems but a short bit of plain track across a join will give every bit as much hassle, I use a long bit,150mm and let it float.

Thanks for the info.

 

You mention reverse curves.

Is that something else which should be avoided?

[DCB]

Thanks for the info.

 

You mention reverse curves.

Is that something else which should be avoided?

Reverse curves must be about the number one cause of derailments and uncoupling.   CJ Freezer who did a huge numbers of plans for Peco and Railway Modeller did the famous "Minories" plan specifically to avoid reverse curves.   Very difficult to avoid where you have crossovers from one track to another but I find the closer the track spacing the less problems crossovers cause, hence carving a few mm off to get down to 44 ish mm on the straights

[roythebus]

If you are building your own track if you use the Templot planning system you will avoid reverse curves. The points on there are based on the prototype, not on "train set" fixed radius curves.

[Chimer]

If you are building your own track if you use the Templot planning system you will avoid reverse curves. The points on there are based on the prototype, not on "train set" fixed radius curves.

 

I'm prepared to believe that Templot is wonderful, and to me people who build their own track are magicians, but I'd still like to be shown a design for a crossover between parallel straight tracks that doesn't involve a reverse curve …….. whatever the radius.

[Grovenor]

Most crossover designs do have a short straight section between the two curves,

shown as dimension A on this table.

Rgds

[rab]

 

I've at last managed to put together a sketch of what I'm trying to do.

(You'll have to excuse te stray lines in the midddle of the turnouts

and the lack of rads on the turnouts; I spent ages trying to fathom

them out and, in the end, gave up).

 

As you will see it's now gone from the 2 turnouts I quoted in the

original post to 4.  I've chosen SL391 & 392's because they have

a 12" (305mm) nominal rad which is closer to the setrack curves

I'm using, (mainly no 2 rad, 10.375 (263mm)).  I know these are

code 55, but I get the impression mixing the two codes is not

a problem as long as packing is used to being the sleeper ht level.

Edited January 11, 2019 by rab

[Siberian Snooper]

I can't see any problems with that.

[Grovenor]

No real problems, but if you have room to add some straight between the SL391 and the adjacent SL392 it would be beneficial.

I have observed, with both points set to the curved road, a wheelset will be hard up against the outer rail and may catch on the tip of the blade as it gets to the facing turnout.

Probably more of an issue with finescale than with RTR.

Regards

[The Johnster]

On a layout with Peco turnouts with stock to current RTR standards and with the use of NEM tension lock couplings, you should have no problems with buffer locking when propelling even through reverse curves, provided that you have taken care to ensure that the turnouts are level and smoothly joined to the tracks adjacent to them whether these be plain track or other turnouts.  This presupposes that all the back to back measurements are correct on all the wheelsets around the entire circumference of all the wheels, that wheel profiles are standardised, and that they are mounted properly and run freely, and also that all the vehicles are of a weight compatible with each other.  

 

Problems will be induced if you fail to keep the turnouts level, or they are not smoothly aligned with their adjoining pieces, or they are located close to baseboard joins that may not be perfectly level or go out of level over time, or if the wheelsets do not run freely, or if the flangeways are blocked by debris, or if driving is rough.  The bars of the tension lock couplings will prevent the buffers from coming in to contact, but if you are using kit built or modified stock to which you have attached your own couplings, ensure that they are the correct distance projecting from the vehicle, and that the bars are all the exact same height above the railhead; don't make the mistake I did of assuming that this is the same thing as being the same depth below the vehicle floor!

 

Despite what should happen, I have only one reverse curve on my BLT, the engine release crossover.  These are also the only small radius Peco Streamline turnouts; the others are all medium radius.  My running is very good and derailments very rare; there is no buffer locking at all and. despite what people tell you about insulfrogs, no stalling (my locos are all 6 coupled steam types) even at the slowest speeds.  The secret, if there is one, is in care taken to ensure that the base is level and the track is smoothly laid.  I use Peco rail joiners to hold the ends of rails in position rather than soldering, which can be vulnerable to expansion and contraction; the joiners give a little 'play'.  I also do not use foam or any other soft material as underlay, as the track tends to 'give' a little under the weight of a train.  I know this is prototypical, but it is asking for trouble on a model unless all vehicles are fully and correctly sprung or compensated.  Lay the track direct to the board, brushing first to make sure no debris is trapped under there, and only use pins to hold in position while you glue it and the glue goes off.

[rab]

Thanks for the responses.

At least I know that, in theory, it should be ok.