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Curve spacing for ho mainline?

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  • Member since
    February 2002
  • From: Reading, PA
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Posted by rrinker on Friday, January 22, 2021 8:31 PM

 As built, with the 3 loops, I can almost guranteed sideswipes with longer locos and cars.

 With just 2 loops, you'd have an 18" inner loop and a 22" outer loop. That's a 4" spacing, and should be fine, although the 4-8-4 and longer cars would have to be restricted to the outer loop.

 If you truly have room for a 4x8, with access on all sides, then you should also have room for an 8x12 donut - it takes the same floor area, minimal access space included. On a layout like that, you have much more room - you can easily use 20" radius and larger curves, which gives plenty of room for a 4-8-4, and anything smaller will look quite nice running on 30"+ radius curves. 

                                        --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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  • From: California - moved to North Carolina 2018
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Posted by DSchmitt on Friday, January 22, 2021 5:45 PM

NMRA Standards Track centers (spacing)

https://nmra.org/sites/default/files/standards/sandrp/pdf/s-8.pdf

 

I tried to sell my two cents worth, but no one would give me a plug nickel for it.

I don't have a leg to stand on.

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  • From: Southern Florida Gulf Coast
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Posted by SeeYou190 on Friday, January 22, 2021 2:43 PM

Traincraft199
Say I did follow the video, would I be at risk of having trains side swiping each other on the curves at all?

Yes.

You would be best to keep that 4-8-4 on the outside loop. Long passenger cars, autoracks, and TOFC flats will not be able to be on any loop.

If you can live with 40 and 50 foot freight cars this can work as you intend.

If this is your first layout, just build it!

Your first layout is a learning experience anyway. Once you find out what you enjoy, and what you don't, you can begin your second layout.

-Kevin

Living the dream.

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  • From: Mpls/St.Paul
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Posted by wjstix on Friday, January 22, 2021 1:41 PM

Traincraft199
I'm just wondering if the tracks are too close for larger locomotives? Should I settle for 2 tracks instead? My largest locomotive is a bachmann 4-8-4 northern, and I want to be able to run it with my other trains without them hitting each other.

I would suggest first spending some time studying model railroading before doing anything. Pick up a couple of books on track planning and scenery and such. (Our Kalmbach friends have a very good selection available!)

When starting out, it can be easy to think in a "train set" mentality, having as much track as possible crammed into place so you can have several trains running around and around each other. In the video you link to is a layout set up to have three trains running in ovals in a space that in real life would only be about 350' by 700'. Less track with more space for scenery, structures, etc. would probably work out better in the long run I believe.

Stix
  • Member since
    February 2005
  • From: Vancouver Island, BC
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Posted by selector on Friday, January 22, 2021 12:26 PM

The thing is, almost none of us ever buys and uses one or three locomotives for the duration of our hobby lifetime.  We evolve in tastes and in our learning, and we often migrate to other rolling stock, some of it quite long.  That's when we realize we could have used a bit more foresight. 

It's never wasted time to mock up a track plan and play with it for a while.  If nothing else, we'll learn in a hurry that what we thought was fantastic and fun....ain't.  So, yes, by all means, build what you fancy, but don't glue it all down in such a way that you can't re-use the rails to try something else, something that now conforms to your modern understanding and newer tastes.  As you get on, maybe in as little as a few months, you'll finally have a track plan that you know will be challenging and fun, and robust in terms of holding your interest.  Also, you'll have figured out how to nest curves so that your rolling stock and locomotives don't make unwanted contact with each other.

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Friday, January 22, 2021 11:43 AM

When I designed my current layout 33 years ago I had one large locomotive and no long cars to experiment with.  I went with 2” spacing on the straight tracks and 3” in the curves.  My sharpest radius is 24” with the norm being 30” to 32”.

The 3” spacing has worked out very well.  Because my layout is small (14’ x 10’) long cars don’t look right so my longest cars are 72’ Athearn passengers.

Most of my locomotives are articulated steam so pretty large, all run fine with 3” spacing.
 

Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

  • Member since
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  • From: Milwaukee WI (Fox Point)
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Posted by dknelson on Friday, January 22, 2021 11:16 AM

When settling on the spacing of my double track main line I somewhat arbitrarily chose 2 inches.  Wider than prototype, but the prototype does not have to deal with huge fingers coming out of the sky to rerail a car or assist an uncoupling action.

The real issue was, OK what about curves?  The standard practice is a wider spacing at curves to avoid overhang from causing interference.  Because only one of my layout's curves is where the prototype had a curve, I really wanted to preserve that 2 inch spacing uniformly on the entire layout, tangents and curves, so I got out some plywood and old brass flextrack and experimented with concentric curves on 2 inch spacing, knowing that I wanted to run full length (not shorty) passenger cars, EMD E units, and 85 and 89 ft flatcars and other long cars.  I had changed era from the steam locomotive era but still have some large steamers and some of them have overhang too.

What I found was that even at 30 inch radius which most people regard as pretty broad there was a risk of interference with the long cars.  Even 36" and 38" radius was awful darn close and it was not impossible to imagine some combination of locomotives and cars running on the double track main that would cause issues at the curves.  38" and 40" radius seemed fine and to be safe I elected 40" and 42" radius at two of the curves.

My point is that squeezing concentric curves on a 4x8 can likely be done BUT you are in a sense selecting against a great deal of modern and/or full length rolling stock in doing so.  Sometimes I shake my head at some postings on this Forum along the lines of "my full length Broadway Limited passenger cars won't run on my [fill in the blanks: Snap Track turnouts, 18" radius curves, etc etc].   There is nothing wrong about 4x8 layouts or tight radius curves so long as you're prepared to accept the consequences for what you run on the layout.  

Dave Nelson

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Posted by mbinsewi on Friday, January 22, 2021 10:14 AM

I like Mobilsman44's sugestion about a "test" track, if you insist on the 3 track plan.

It's not just about the locomotives, but also using the longest cars your going to be running, for your test of clearances.

Mike.

  • Member since
    September 2003
  • From: Southeast Texas
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Posted by mobilman44 on Friday, January 22, 2021 9:49 AM

I would urge you to tack down the curved tracks and experiment first.  Using a 4x8 for dual HO mains with large locos is real challenge at best.  If there was any way of adding even 6 inches to the width, it would make it so much easier.  

Of course using sectional track makes it difficult too.  Flex track would give you more precise spacing, but I do understand it can be a jump for some to go from sectional to flex track.  Yes, "been there, done that".

ENJOY  !

 

Mobilman44

 

Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central 

  • Member since
    July 2020
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Posted by Traincraft199 on Friday, January 22, 2021 9:38 AM

Say I did follow the video, would I be at risk of having trains side swiping each other on the curves at all? all my other locomotives handle an 18'' radius fine and I'm ok if I can only run the 4-8-4 on the outer 22'' radius loop. I can settle for 2 tracks if 3 tracks would be too close to each other

Building my first layout, 4x8 contemporary urban area in HO scale 

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Posted by wjstix on Friday, January 22, 2021 9:18 AM

That video is 'different'. What he's doing is a 22" Radius oval on the outside, and 18"R on the inside, with the middle oval being alternating 18" and 22" sections to work out to the equivalent to 20"R. I guess you could do that, although larger engines and cars may not like 18"R curves.

If you're new to model railroading, I would go for something much simpler as a first layout. Maybe just a 22"R oval with some spur tracks for industries?

It also appears he's using Atlas snap-track and ballasting it - didn't catch if he's using cork roadbed. For a first layout, I'd suggest using one the 'click track' options, track with roadbed and in some cases simulated ballast already in place. That type of track is made by Kato, Atlas, and Bachmann, and due to the way it's made tends to be easier to lay and to wire up and keep electricity going to the trains. Plus it allows you to try different ideas and run trains without needing to glue or fasten the track down permanently right at the start.  

Stix
  • Member since
    July 2020
  • 42 posts
Curve spacing for ho mainline?
Posted by Traincraft199 on Friday, January 22, 2021 8:58 AM

I'm kinda new to model railroading. I saw this video of 3 ho tracks squeezed onto a 4x8 and I thought it would be perfect for my first layout. https://www.youtube.com/watch?v=eBbTXXNff-E

I'm just wondering if the tracks are too close for larger locomotives? Should I settle for 2 tracks instead? My largest locomotive is a bachmann 4-8-4 northern, and I want to be able to run it with my other trains without them hitting each other.

Building my first layout, 4x8 contemporary urban area in HO scale 

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