[Twiglet]

A basic question on curves (and planning):
I am constructing my OO attic layout using Peco flexitrack. I am lucky enough to have a fair amount of space (a ring 5M x 4M) and hence I have tried to use the largest-radius curves as possible, with long gentle sweeps and gentle transition curves where there is space. But this has all been done more or less by eye - using pieces of setrack of different radii as 'guides' to make sure things are not getting too tight and making sure clearances are sufficient. It's all very trial-and-error, lots of jiggling about and nudging lengths of track here and there, but seems to be working so far. I have not calculated curve radii precisely or even done more than sketch out the plan on the boards - I have just made the track 'go where I want'. Is my approach OK or is it likely to lead to disaster? As far as I can tell, if the rolling stock is happy then all is well ....

 

[Doug]

It shouldn't lead to disaster, but it is a good idea to "survey the landscape" and lay track as smooth as possible. This way, the OO scale passengers will get a better ride.

I use string with a thumbtack on one end and a pencil on the other to draw out large radius curves and then I lay the track to the curve.

 

[Twiglet]

QUOTE (Doug @ 30 Nov 2008, 08:04) <{POST_SNAPBACK}>It shouldn't lead to disaster, but it is a good idea to "survey the landscape" and lay track as smooth as possible. This way, the OO scale passengers will get a better ride.

I use string with a thumbtack on one end and a pencil on the other to draw out large radius curves and then I lay the track to the curve.

Many thanks for this advice; Do you use this method even for minor changes of direction? Surely if it is clear that a curve is of sufficient radius to allow unhindered movement then you don't need to 'check' its radius?

 

[Doug]

I use this for any change where there is at least 90° between direction of travel. I want the curves on my mainline to have curves over 30" radius allowing fast running with no danger of derailments.

In the book Track Planning for Realistic Operation, John Armstrong recommends the following standards for curve radii:

	N-gauge	HO/OO	O-gauge
Broad curves	17"	30"	58"
Conventional curves	14"	24"	46"
Sharp curves	11"	18"	35"

Now I'm using 36" curves on the mainline in places and it looks great. If you use tighter curves, you will just have to reduce speed and negotiate them more carefully.

 

[Richard Johnson]

QUOTE (Doug @ 30 Nov 2008, 21:05) <{POST_SNAPBACK}>I use this for any change where there is at least 90° between direction of travel. I want the curves on my mainline to have curves over 30" radius allowing fast running with no danger of derailments.

In the book Track Planning for Realistic Operation, John Armstrong recommends the following standards for curve radii:

N-gaugeHO/OOO-gaugeBroad curves17"30"58"Conventional curves14"24"46"Sharp curves11"18"35"

Now I'm using 36" curves on the mainline in places and it looks great. If you use tighter curves, you will just have to reduce speed and negotiate them more carefully.

I think John Armstrongs recommendations are way off the mark with todays models: Defining 30" as broad is simply wrong - its visibly uncomfortable with full length coaches and large engines!

My opinion:

target minimum even in concealed area 24"
target minimum for visible track 36"
ideal for realistic look 60" or greater.

I know its not always practical, but the best advice is "do it as large as you can, always".

Mike - the way you did it is fine, and Dougs idea of using a radius arm or string is good too, but try to always have soft transitions between curve and straight, not do from radius to perfectly straight at any one point a happens with set-track - thats what makes for bad running and looks toy-like!

A "transition"" is a gentle change from curve radius to straight track: Track and trains look and run better if curves all have transitions.

The easy way to lay a transition is to draw the radius then offset the stright track 100mm outside that. Add several nails about 30mm apart just either side of the radius mark a few derees before it parallels the stright track mark and insert a flexible 36" ruler or even a strip if thin ply/plastic or a loose length of dowell or rail between them. (the idea is the nails hold the end of the ruler firmly to te curve.

holding the far end of it. curve it until it smoothly meets the offset straight track line, and use it to draw the transition section line. Lay track to the lines drawn.

Richard

 

[34C]

It is well worth deciding on a minimum radius (and if they are to be employed a maximum gradient) for a layout. That makes it possible to arrange coupling distances between vehicles, such that they will just negotiate the minimum radius; with a consequent improvement in appearance over RTR stock with couplers set to a spacing to permit very tight curves.

Doug's point about reliability is a very good one, in OO I have found that for close to absolute reliability when operating full length trains requires curves of 30" radius (or greater) on the running lines. If trains are then operated at linearly scaled speed, they rarely derail, even in the event of a 'crash stop' caused by the power system tripping out. In the good sized space you have available, with transitions into curves as well, a very fine appearance may be obtained if radii are kept generous. I have seen some most successful examples where there is practically no straight track in the scenic areas, which are dominated by gentle curves (think tens of feet radius), the eye then readily accepting the sharper curves at each end of the scenic area where trains run out of view as the effect of distance compression.

 

[Twiglet]

Thanks again for all the advice ... the last point a good one - have tried to avoid dead-straight track as much as possible. I have found that if you get down and peer along real railway tracks at ground level, even supposedly straight sections, they bend all over the place (and rise and fall like a roller-coaster).
As an aside, lots of space not always a good thing. Means you a) get slapdash ('can always make it fit') and - especially in my case - overambitious.

 

[alastairq]

get a large piece of old cardboard, and scribe/cut out a curve to your minimum raduis.

[remember, such a minimum can be reduced for sidings, or track intended for very low speed operation]

Lay out your flex track to the shape/plan you desire, and test it against your template.......it is no sin to have curves of odd figures, to a broader radius than your minimum.

once initially positioned, try some pieces of stock...coaches are useful, over the track to see if there is anything about their motion that jarrs with you....and adjust before the gloo sets.

the big problem in my view, regarding the use of flex track and turnouts, is the fact that these turnouts can never achieve the ''tailor-made'' look of the real thing.

No matter how ''flowing'' you get your plain trackage, there will always be that ''dead-straight'' section of each turnout to disguise.

In this issue, I try to use, as much as possible, very long turnouts and curved or wye turnouts......somehow they seem to fit a flowing track design better.

Avoid S-curves if at all possible....and if not, try to have at least a coach or two's length of fairly straightish trackage between the two opposing curves.

T' me, no matter how devilishly fiendishly cunningly good an overall track plan may be.....if the displacement of coach ends is anything like extreme, the impression is lost.

 

[bluey robinson]

Another point to consider is the environment through which your track is placed, ie in a built up area changes of direction, from my observation, seem to be more short stretches of bend with lengths of straight, wheras through countryside sweeping curves are usual. Consider your topography to give your curves some "meaning".

Cheers, Bluey

 

[34C]

QUOTE (alastairq @ 30 Nov 2008, 16:25) <{POST_SNAPBACK}>.. the big problem in my view, regarding the use of flex track and turnouts, is the fact that these turnouts can never achieve the ''tailor-made'' look of the real thing.

No matter how ''flowing'' you get your plain trackage, there will always be that ''dead-straight'' section of each turnout to disguise.

In this issue, I try to use, as much as possible, very long turnouts ..
Two possibilities here in RTR track. Tillig provide the ability to flex nominally straight turnouts as part of the design. And since you glue your track down it is worth mentioning that Peco's large radius turnouts can also have a slight curve put into the straight road, with no detriment to their operational reliability. To enable this it is necessary to cut slots through some of the sleeper webs on the inside of the curve, but leaving the crossing untouched. The improvement in appearance in a sweeping curve more than justifies the effort involved when compared to using them 'straight'.

 

[Robert Stokes]

I echo the last comment. I have done the same thing and it really does improve appearance. It only needs to be a very slight curve to get the desired effect.

Cheers, Robert.

 

[alastairq]

I agree modifications can be made to the likes of Peco....what we have to consider is the ''willingness'' of a modeller to take the plunge and hack into what might be seen as an expensive bit of kit?

After all, a snip too far or a tweek over much can junk an expensive turnout? Perhaps a short note to demonstrate exactly what to do to modify a peco turnout might not go amiss?

 

[Sol]

QUOTE (alastairq @ 2 Dec 2008, 05:47) <{POST_SNAPBACK}>I agree modifications can be made to the likes of Peco....what we have to consider is the ''willingness'' of a modeller to take the plunge and hack into what might be seen as an expensive bit of kit?

After all, a snip too far or a tweek over much can junk an expensive turnout? Perhaps a short note to demonstrate exactly what to do to modify a peco turnout might not go amiss?

My Peco points - the few I have are all modified before laying like adding wiring joining blades to stock rail, dremelling a cut both sides of the frog to give a "dead" frog - does not need switching then. I even had to replace a tiebar with PCB sleepering as the blades came adrift. I normally cutoff the pips on tie bars & have cut away a lot of the plastic that is part of the point-motor fixing as they are operated by rodding thru the centre hole from either Tortoise or motors well to the side of the point. They can be repaired & after painting & ballasting, don't look much different from un-touched units.

Yes, curve the points slightly, it will look better & match with curved track.