radius turns

[mwalther]

This is similar question to what radius, only in the vertical dimension. General answer is: as small as possible. Practical answer is dependant on how high you need to go (crossing other tracks below?), whether the grade is visible, how long your train will be and how much grade and train length together that your engine(s) can handle and of course, how much space (length) you have available. The first thing I would do is buy Track Plannng for Realistic Operation and read and read it.

Then you need to consider that the grade can't simply begin and end at 2 level lengths of track, but must instead transition from grade to level or indeed to any significant difference in grades. Otherwise the pilot or "cowcatcher" at the front of your engines will be digging in to ties at the bottom and the lead and trailing wheels of your steamer may be above the rails at the tops (derail) while the center wheels could lift off at the bottom(derail). Remember that a 1% grade to rise 1" will be 100" long without the transition length. This could push a 4% grade to rise 4" out to 100" plus the transition length to more than 10-12 feet in length. The need for transition length sometimes forces you to use steeper grades for the actual rise (which then require longer transitions). What is the perfect compromise?

If your grade doesn't have to be completely visible, you could consider a Helix which is a continuous grade that spirals over itself like threads on a screw to get the long length of run in a short space. Helixes may require large radius curves to allow for the track and roadbed to clear the tops of trains on the spiral tracks below. Building helixes is beyond my scope here, but you can read about them in many MR books and probably in this forum. You could bury it in the ends where you are going to put your curved track.

I too am struggling with all this. Grades are the bane of both model and real railroads, but they are often necessary for both to accompli***heir purpose. Mark

[Anonymous]

Thanks guys those last post help alot

[Paul Milenkovic]

I just put together an HO display/continuous running layout in 35" by 24" space -- the track plan is a twice-around loop with 5 percent up and down grade and 10" minimum radius. So far I have operated a 40' scale Athearn switch engine on it and it runs just fine -- I plan an getting a 4-wheel industrial loco and some short freight cars, or perhaps kitbashing one of the those European articulated DMU passenger trains.

Nope, this layout won't run 6-axle Diesels, Big Boys, or Superliner passenger cars, but if you are willing to accept restrictions on your equipment, it will run just fine.

I also think there is too much a break between "scale model railroading" and "toy trains" although tin scale has made a comeback -- the folks who don't want to be seen as adults "playing with toy trains" rationalize this with tin scale as being a collectable.

The model airplane folks are much less concerned. Their emphasis is on getting the thing to fly, and they have a continuum of models, from models that fly and have the most remote resemblance to any prototype to highly-detailed scaled models.

My 35" by 24" inch layout is an experiment in doing HO using tin-scale grades and curves.

[BRJN]

y2snow:

The most slope the real railroads could have was about a 5% grade - a slope that went up 5 feet for every 100 feet it travelled across. Madison IN had a hill outside of town with a 5.85% slope; this required VERY short trains, specially geared engines, and the regular road engine as helpers.

But on a layout, you can get away with 5% slopes because the trains are shorter anyway. This is not enough to create a roller-coaster tilted curve with extra radius in a given depth.

An 18" radius curve (36" across) allows you to run diesels with a B-B footprint (two trucks, two axles each). I expect a 15" radius curve could also take the same engines if they moved slowly and carefully.

If you want to have a 1900-era layout, the road engines will be 4-6-0 or maybe a brand new 4-6-2. 4-4-0's were still common in general service. Most freight cars were 40' or a bit less in length, and will fit on small curves without difficulty. Your trains will need to be rather short; estimate 20-30 cars until you actually build the layout and see how many cars can be pulled through the sharp curves without falling off the track or anything.

I used to have a 4x8 loop and once tried putting an engine and as many cars (mostly 40'-50' ) as I could fit on the track, hooked them all together, and set out forwards. Half the train fell over because it was being pulled 'sideways' around the curves. So that was too much. But about half that - 12 feet long or 24 cars - worked for just going and going around and around, not too fast.

[IRONROOSTER]

This page http://www.nmra.org/standards/rp-11.html shows some recommended curves for different lengths of car and engines. While some manufacturers may engineer some of their locomotives to take a tighter radius, this will give you a general overall guide.
Enjoy
Paul

[Anonymous]

i would go with a maximum, remember MAXIMUM of a 2% grade. What that means is that for every 100 linear inches you go, you go up 2 inches. It doesnt sound like much, but much more and your trains will have trouble going up the hill.

[mcouvillion]

Correct. Just widen enough of the layout surface to fully support the track loop. It won't be very big. Make a circle of 18" snap track and lay it on the 36" wide surface. You will see how much you need to add to get clearance all around and support it in the front.

Mark C.

[Anonymous]

Ok to sum this up if i want a loop at one end and i am running 3' against the wall at the end i could widen that to 4' and i will be ok for a loop correct?

[Anonymous]

I'm keeping with the 3x24 but with switches that would a good challenge, got one last question i wanna do a side of the layout a mountain what the degre of going up or down

by the way thanks for the tips guys

[Anonymous]

Hello y2snow, as Marc C. said "am I missing something?" When you have determined exactly what the maximum deminsions of your pike will be; it would be well to resubmit that data on another Forum entry. Until then, there isn't much anyone can suggest in a definitive manner. Probably the last thing you want to hear is the possibility of running a traction road (over-head wire) with multiple unit interurban service combined with steam powerd (2-6-0 maximum) way freight operations. If you must adhere to the lesser deminsions [3' X 24' ], this mix of traction and light steam will afford you variety and challenges that will never bore you. If, on the other hand, you prefer a "roundy-roundy," i.e. dog bone, inverted 8, etc., plus using heavier steam, then the second option of 6' X 24' is a must. In the long run, I think you will find "point-to-point" will offer the greatest opportunities for prototype operations and continued entusiasm for the hobby. Just another humble thought to add to the excellent suggestions previously mentioned. Good luck

[Jetrock]

I think there is some thematic disparity between the "sharp curves are all right" crowd and the "curve radii less than 22 inches simply do not exist" crowd.

Indeed, what might work best, if you have the room, is a "dog-bone" layout, with curves as wide as you can manage at each end and a nice long skinny section in the middle, maybe two feet deep, for good access, as mentioned above.

y2snow: Much depends on exactly what kind of railroading you hope to model. You mentioned steam--but do you want to model gigantic articulateds pulling heavy freight, or little geared logging locomotives? Your requirements in terms of curve radii and space depend very much on what sort of layout you want to build.

[mcouvillion]

It looks like we are fightin' the alligators when we went in to help drain the swamp. I don't understand the huge change in dimensions mentioned: 3' x 24', then 6' x 24'. In my opinion, 3' x 24' would be wonderful, but the last 36" at each end would have to have a 6" by 24" extension to allow the trains to turn on 18" radius curves and have a little bit of clearance all around. You could do all kinds of railroading in the 18' - 20' between the turns at the end. Am I missing something?

Mark C.

[Anonymous]

i used to have a layout i couldnt reach across, what i did was to cut a hole in the layout inside the curve big enough to stand up inside. You have to figure out a way to put the piece of layout back in place when you dont need to climb through it, that way, if something derails and you cant reach it. Just lift out a piece of the layout, crawl underneath, pop up and retrieve it. Of course ideally, nothing should be derailing at all.

[ndbprr]

Welcome to problem #2. if you make it 6' wide you better have arms like an Orangatan because you won't be able to reach the center (was that a groan I just heard[:)])? a couple of things to consider doing:

1. Make the ends 48-72" so you can use a larger radius and keep the center 3' wide so you can reach into it when you need to.
2. Make the railroad 30-36" wide around the walls of the room and stand in the center
3. Makethe railroad point to point by not putting a loop on one end and run back and forth switching cars with a loop at one end.

With 24' of length that is a pretty healthy size in that direction. You might want to consider hiding the loops under a city or mountain. You certainly have enough horizontal distance to have a whole switching area above the lower level over one or both loops. You could then make the focal point of the railroad a crossing in which the basic layout is a figure eight with interchange tracks between the two lines. It would be a case of dropping off cars for interchange on one side of the lap and picking them up on the other. two tracks would add variety in that regard as the cars dropped today are picked up tomorrow. You could basically have a road cab that could be operated from the center of the layout at the crossing and two or more switching cabs for walk around control.
Just a couple of ideas off the top of my head.

[Anonymous]

Thanks guys,

ok i'm trying to make it up 6' by 24' i'll try to move some stuff and maybe i can get it or maybe more then 6'. So for being safe i souldn't go for less then 22" radius, right

[mcouvillion]

y2snow,

If your benchwork is 36" wide, you still can't get an 18" radius on it because that's the centerline of the curve. Your equipment will overhang the outside rail on the curve anyway. Would it be possible to attach a small extension to the front of the ends of the benchwork so that you could support the track for an 18" radius curve? It wouldn't take up too much additional space (maybe 6" by 24") and would make all the difference in the world. Old-time steam is pretty small and would not be a problem on 18" radius curves. I'd use snaptrack for this application.

Good Luck!

Mark C.

[Jetrock]

y2snow: As mentioned above, much depends on what sort of equipment you want to run. Large steam will simply not run well on very tight curves--but if you want to run very small steam (like an 0-4-0 switcher) then 3 feet is enough space for a 15" radius loop of track. That 24' length is nothing to sneeze at--lots of room for scenery or switching in a fairly straight line!

A 15" radius loop at each end will limit your operation to short cars (40-50 foot freight cars or "shorty" passenger cars) and smaller steam (the aforementioned 0-4-0, maybe a 4-6-0 at absolute maximum), at least for what you'd like to go around the loop. Since you'd have more than 20 feet of track that's NOT a 15" radius curve, you could operate whatever you wanted in the middle of the layout--it'd just derail going around the loop if it was too long!

Heck, that might create some interesting operation problems...the big road engine needs help from the dinky switcher to retrieve cars for the Red Ball Freight from industries located around "Deadman's Curve"!

[Anonymous]

buying old track is sometimes a good idea, sometimes not, if you can get a lot in good shape then go for it, but try to stay with nickel silver track because it stays cleaner longer than brass or steel

[Anonymous]

the only tool is maybe a large compass to draw out the radius before you bend it, that way you get a smooth curve, but you can just bend it easily in your hands. a good place to order track and roadbed in bulk is www.standardhobby.com the only problem here is you must order a lot at a time. If you dont need so much look on www.discounttrainsonline.com

there are plenty of other sites too, there are also ads in the model railroader magazines

[Anonymous]

ok thanks, now the flex track is there a special tool that one need to purchase to make the curves? Can you give me some good online hobby shop since i will be ordering all. I am in Curacao there is no local hobby shop here. Would you recommend buying used track from other modelers?

[Anonymous]

i'm looking for the old scenery like steam machine, old cars and old house

[Anonymous]

brian, its a common mistake your making, radius is HALF the distance across the turn, so 3 feet would be and 18 inch radius so no and as for your second question, you can buy track piece by piece from various manufactureres, but you will get better operation by using flex-track, it comes in 3 foot pieces and you bend it to the size turn you want, it can also be used for straights. if you plan on using this invest a few bucks in a good pair of rail cutters so you can cut the 3 foot length to the size you need

[Anonymous]

Also being a newbie i wanted to ask the same question. I've yet to see a solid answer. If the width is 3 feet that is 36 inches would that be enough for HO scale? 30 inch radius will work correct?

Also what would be the best track brand to purchase and do you purchase them piece by piece or is there a kit complete set available?

[Anonymous]

3 X 24... now thats something, sounds like you could make a pretty spectacular switching layout there. now, about a line running all the way around, have you considered a point to point style layout. its true you cant just let it run and maybe youre not quite ready for a lot of operations... another important question though. whats your era ( the time frame you are modeling)

[Anonymous]

sorry mark C,

its HO scale, does it show that i'm a beginer lol, for the space for now is realy short i have something like 3 foot by 24 foot. But the problem is that i want to do at least one rail go all around the table see my problem ? For a radius of 21" don't have the space for it

[mcouvillion]

y2snow,

You did not mention the scale you were using and the first answer assumed HO. So much depends on the scale, what type of rolling stock you intend to run, the locale you intend to model, and your personal preferences. Overall, "the larger the better" is the preferred response, but may be inappropriate for your particular situation. The other specific suggestions above are excellent.

Mark C.

[jhugart]

Smallest radius without problems? Depends on what you can accept, and what kind of thing you are modelling.

A streetcar will take sharper curves than a streamlined passenger car.

The actual dimensions of the radius depend on the scale you are using. I think Atlas makes a sectional 9" radius track for N. Z scale can have a layout in a briefcase.

There are some techniques to handle the transition from straight track to a curve in a way that hides some of the ugliness of the sharp change. Take a look at Track Planning for Realistic Operation, it has tables in it for radii for different scales and types of curves (narrow, conventional, broad).

Good luck!

[ndbprr]

A very innocent question with sinsister consequences! Basically the answer (first) is as big as you can possibly make it. Now the reasons. 18" is the smallest practical and will limit what you can do severely. Large road engines and 85' passenger cars will have tracking problems. Forty foot box cars and four wheel truck engines or steam switchers will be all you can easily run. Bump that to 22" and you might still have problems with the bigger equipement although much fewer. Want realistic operation and looks that will allow virtually anything to run with little or no problems consider 30" radius or larger. My Pennsylvania railroad corridor layout being built as we speak will have 48" minimum and most of the time even bigger. For the first time space isn't a consideration and I have asked multiple times in multiple forums if anyone ever regretted building a layout with curves that big or biger. Everyone who has repsonded said absolutely not without one dissenting vote. Now I suspect from your message you are fairly young and a 4' x 8' may be all you can muster at this point but do not be discouraged use 22" when you can and you won't regret it.

[Anonymous]

im building a layout of my own but i'v got a question.
what's the smalest radius we can use without causing any problems


thanks