curve radius

Hello and welcome to O Scale!

As you noted, bigger is always better, but O72 isn't always an option for us. O54 will allow you to run a good chunk of the Legacy roster Lionel has produced. You will not be able to run any of the big articulateds (Big Boy, Allegheny, etc) and the larger rigid frame engines (eg, 2-10-4) on O54, but most everything else will work fine, generally including scale 4-8-4's (eg, N&W J Class) and smaller (of course check the manufacturer website or the box to verify, some models are different). For O42, I can only recall the Shay's having O42 requirements, everything else I have seen has either been O36 and smaller or O54 or larger.

As an aside, I am inclined to believe that O72 could be made to work in a room of that size without just being a giant circle, but that depends on how much space you want to give to the layout, and I am not a track planning expert, so I won't say anything else about that specifically. Since you are coming from HO, I will make a note that 3-rail O scale's radius convention is a bit different from 2-rail O scale (and every other scale), in that the listed radius - eg, O72 - isn't actually the radius, but is the diameter of a circile of track, measured center rail-to-center rail. A plain circle of O72 has a radius of roughly 3', and would take up a little over 36' sqft of space. You may already be aware of this but I thought it still worth mentioning.

@Keith1366  to help you plan your layout and to get more specific input from Forum Members, you may want to look into downloading Track Planning software to try out different options for your space.  One of the most commonly used here is SCARM.  It's free to use up to 100 pieces of track, and if you like it, the full version with all options is $39.90.

First, just a little correction to the previous post.  Read thru this forum and I'm sure you will find enough references to the fact that not every O gauge manufacturer measures radii or diameter from center-rail to center-rail.  Most are close, but if you mix manufacturer's track pieces, you may run into problems.

Second, I constantly find my self giving the same two pieces of advice:

1. Look through this forum and search the web for track layout plans that will approximate your space.  While I know this will be the newbies first instinct, you might be better served by first reading up on model railroad operations because how you choose to operate, and how realistic you choose to be, will have a dramatic impact on what you plan to build.

2. Acquire at least one piece of track planning software.  If you have access to a Windows computer, there are a number of recommendations including SCARM and AnyRail.  Both are free to try out by creating a layout with up to 100 pieces of track.  There is another one, XTrakCAD, but while it is completely free, I have found it a little more difficult to use.  Finally, there are the paid versions which I don't use so I'm unable to comment on their usefulness.  However, if your computer access is limited to Apple Macs, the track planning software you can use is much more limited (Rail Modeller Pro) unless you use another program that lets you run Windows programs on Macs.

Chuck

Forgive me, but didn't Lionel originally use the outside diameter measurement to market their track as 027, 031, 072? I seem to recall diagrams in old Lionel publications showing this.  I mostly use flex track and draw my own curves but just curious.

Earl   

https://www.bing.com/images/se...ist=0&ajaxserp=0

Yes, they did.

If you are going to use Gargraves you are not limited to the standard curves.     If you need O-68 1/4, make it.  John

My layout used mostly Gargraves Flex track, I have curves that are... well... almost any diameter.

Thanks for the info.
I have anyrail software I am using to design the layout just trying to figure out how limiting the smaller curve radius will be. 
Once I get some planning narrowed down I will share the plan here for feedback.

All of the above posts give good advice. One thing to consider is that since you're looking at 3-rail equipment, if you can, use O-72 or larger diameter curves. To date, everything produced in 3-rail can negotiate O-72 curves, so your future acquisitions will all run on your layout (give yourself about 6" between the outside of the curve and a wall).

Thanks again for the info here is a first rough draft to fit the room it has 054 curve min. with easements on almost all curves the curves that do not have easements are 0 120 and 0 132. I used fastrack spacing of 6" between tracks throughout, and I have 4-4.5 inch from center rail to wall which can be increased a little if recommended.

This is just the lower or main level double main line. Still need to work in crossovers and reverse loops.

Personally, I'd reduce the entry a bit and make at least the outside tracks O72.  I'd also consider a lift-bridge across that opening to allow a complete loop.  Trust me, you'll never regret making the curves larger!  Other than one minor industry siding set, nothing on my layout is less than O72.  This was learned from hard experience with previous attempts.

Here's a graphic for those that don't have AnyRail.

@Tom Tee posted:

Anything else is a compromise.

What he said!

What they said, my first attempt was 0-54 curves and with fixed piolets it doesn't work. So now everything I have is 0-72 all the way around the room with a bridge lift section. Here is a little video of what I built for the lift section. But there are several different types.

Hi Keith, you have a nice space & I recommend you take advantage of it. It’s been mentioned multiple times here and elsewhere, keep your minimum radius to 072 & NO duckunders!!! You will not regret these 2 suggestions. I built my layout when I was 40 & now at 65, my back & legs hate the duckunders! Thankfully I was smart enough to keep my minimum to 072 & 081. My outer radius is 0120. Guaranteed, everything you run will just look more realistic.

@ironman1 posted:

Hi Keith, you have a nice space & I recommend you take advantage of it. It’s been mentioned multiple times here and elsewhere, keep your minimum radius to 072 & NO duckunders!!! You will not regret these 2 suggestions.

Nu duckunders, check and check!  O72 or larger, check and check!

👌👍

Over the years I've never had a problem finding the pieces of Atlas track that I needed.  I've  just had to look longer at times.

Jan

Keith What did you run in HO? Short or longer equipment?      HO sets come with  18"R circle of track, the equivalent on O Scale is O72 (36"R) or twice the size. 

One thing you could look into is hiding your curved sections. I am going to use 0-72 and 0-81 curves for the ends of my layout to turn the train around and I will put most of it under a mountain. The visible portions of curves will be 0-90 and above except for one section where I couldn't avoid it. This should help ease that fake looking over hang situation that you see with longer locomotives. There are videos out there showing Big Boy over hanging a lot like our models do. So it isn't entirely unrealistic. It looks as goofy in real life as it does on our models.

You'll also increase the size of the layout if parts of the curves are hidden. Particularly if you can place buildings over the curve, between the mountains and hide the tracks that are running them through the building. I'm employing this method to hide one of my curves completely. You might also look at elevating a curve and making it come out elsewhere. That's one of my favorite parts of HO. You see trains enter a tunnel and they drop under the table, only to come out on the other side of the layout. Or they will be go under the layout and go through a reversing loop so that they come out through the same tunnel they went in. I think it's a clever way to create the illusion of a bigger layout. Hope that made sense.

Side note: The Atlas shortage has crept up again but only in the form of being stuck at the dock from what I have been told. The track is being produced but transport has become tricky.

The thing I get caught up in with O scale is I like the "Display" type layout I like the idea of several trains running and just playing with trains. My HO layout has 24" and 26"radius with #5 turnouts, I limit myself to small equipment on the ho layout not so much for looks but for running reliability.

I am working on drawing the layout with the main lines being 072 min and lift out bridge across the doorway. I am working on the upper loop with it being 054 and 072, not sure which looks better for now. I like the way the design is coming together but it will require access hatches . I like the flow of this one but it has a lot of wide benchwork and some switches that or not in ideal placement.

One recommendation, make space for more yard tracks!  I had three 15 foot yard tracks, not nearly enough!  I added a freight yard with ten 12 foot tracks, and I could still use more yard space!  I suspect it's hard to have too much yard space.

That looks like an exciting track plan. There's a lot of opportunity for scenery and industry although it doesn't sound like that's exactly your thing.