# Minimum Track Radius



## BalsaBob (Oct 21, 2013)

Hello, I am new to garden railroading and plan to start a backyard layout. I would like to make my outer (main line) able to run a live steam loco. Wondering what the minimum radius should be to be able to run some basic (small - medium) live steam locos. This outer main line will have 0 grade. I am planning to use USA Trains track which offers 16 foot and 10 foot diameters. Is the 10 foot diameter acceptable for my needs ?

Thanks. Bob


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## Tom Bowdler (Jan 3, 2008)

Bob,
My first garden railway had 10' diamter curves and I was able to run most small live steam locomotives up to an Accucraft C-16. Most four or six wheeled locos should be fine.
Have fun,
Tom


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## Jim Overland (Jan 3, 2008)

Bob,
There is a difference between what CAN run and what SHOULD run
Larger radius is always better
jim


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## chuck n (Jan 2, 2008)

Our general recommendation is to use the widest radius curves that will fit into the available space. The larger the radius the better your trains will look. When I built my layout in 1993 10' diameter sectional track was the widest available. I wish I'd have used flex track and made the curves bigger. 

The overhang on longer cars and engines is very noticeable (such as longer diesels and modern passenger cars). 

I do not have any live steam engines, so I can't specifically answer your question. I think that short wheel base steamers wouldn't have a problem. 

A regular here "Phippsburg Eric" has a very nice layout in Maine. Most of the engines I have seen in his pictures are smaller ones. Search through his posts and see what he has done. He will probably have some good advice on choice of curves.

Plan for what you might want to run in the future, not just what you think you want to run now.

Chuck


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## David Leech (Dec 9, 2008)

Bob,
It really all depends on 'why' you are building your railway.
If it will just be for yourself, and you plan on never having anything larger than say a Ruby, then it perhaps doesn't matter.
If you might be inviting friends over to steam and they have larger Hudsons or Mikados, or whatever, then 10 foot radius (20 foot diameter) using flex track would be the way to go.
I would check the manufacturers specifications on minimum radius requirements on any locos that you may want in the future, and build accordingly.
Maybe you are going to concentrate on small narrow gauge, or you might be thinking mainline standard gauge.
You need to think ahead, if I were you.
Nothing worse than in a couple of years, wishing that you had done it all differently!
Have fun,
All the best,
David Leech, Delta, Canada


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## vsmith (Jan 2, 2008)

Although I am the most vocal advocate for small radius curves here, even I have to agree that when it comes to live steam wider IS better. Steamies are notorious for being finicky about track. The last thing you want to risk is a very expensive steamie taking a nosedive off your track. Also going wider means greater flexibility and the future option to aquire bigger engines. So maybe 16'for dia min?


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## Semper Vaporo (Jan 2, 2008)

When checking manufacturer's specs, be sure to note that some use RADIUS and others use DIAMETER... don't get them confused, it can be a source of regret!  

And be prepared to do a lot of Metric <> English conversions!


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## Dan Pantages (Jan 2, 2008)

Metric<>American conversions?


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## Totalwrecker (Feb 26, 2009)

Yes metric to foot approximations....


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## David Leech (Dec 9, 2008)

If you want to get picky, it should perhaps be:
Metric<>Imperial and US customary measurement systems (both based on the ENGLISH system) conversions!
Regards,
David Leech, Delta, Canada


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## Semper Vaporo (Jan 2, 2008)

Ok...

Lemmee rewoid dat...  

"And be prepared to do a lot of unintelligible <> intelligible conversions."

and then let everyone decide which is Metric and which is not, regardless of which name they want to give it... then everybody can be smugly satisfied that they are right and the other form is stupid. 





PKGS. !!!


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## ntpntpntp (Jan 14, 2008)

to paraphrase a line from one of my favourite films: 
"let's just say we'd like to avoid any Imperial entanglements!"


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## BigRedOne (Dec 13, 2012)

I'd try to go with the 16 foot diameter if you have the room. Everything looks and works better the larger your turns, and you gain the ability to run more diverse equipment in the future.

That said, have you considered flex track? Flex allows more flowing curves, gentler curves where space affords, and fewer joints. You can also use a code 250 rail, which is visually more realistic. If you are not planning track power, aluminum track is about half the cost of brass.


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## Scottychaos (Jan 2, 2008)

The question should never be: "what size curves should I use?"
the question should always be: "what is the largest diameter curve I can possibly fit into my space?"..then use that.

Scot


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## SD90WLMT (Feb 16, 2010)

This is a hard message to communicate to people moving up to Gscale....

Getting away from the smaller scales. Is a shock at first...

D


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## chuck n (Jan 2, 2008)

Here are some pictures of a longer engine (USAt SD70MAC) and longer car (USAt streamliner) on 10' diameter curves.










Car on left on curve, car on right on straight track about to enter curve.










USAt coach on 10' diameter curve.










This is why I wish that I had used wider curves when I built my layout.

Chuck


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## vsmith (Jan 2, 2008)

Scottychaos said:


> The question should never be: "what size curves should I use?"
> the question should always be: "what is the largest diameter curve I can possibly fit into my space?"..then use that.
> 
> Scot


I would modify with that by adding this qualifier. Use the widest curves that will still give you an interesting layout.


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## deltatrains (Nov 25, 2010)

*Wish I got it correct the first time !*

Hi Balsa Bob, I hope that you install the largest radius curves you can possibly fit into your available planned area. I originally placed 5 ft. radius curves and once I got into live steam found out that I needed at least 10 ft. radius curves for smoother running. As always it is more difficult to re-do everything than to get it right the first time. Learned my lesson and here is an old video I made when the rebuild was completed. Live steam at the 5 minute mark if you want to jump directly to that. Link:




All the best, Peter.


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## Randy Stone (Jan 2, 2008)

When I first got into G, I was planning to stay with smaller locos and shorter frt cars. But like so much in life I decided bigger was better. Dash 9 and usat passenger cars will trafferse the 8ft dia curves but it ain't purity. So I'm with those who say use the largest DIA you can fit. You can always put tighter dia curves in the center for smaller locos.


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## BalsaBob (Oct 21, 2013)

Thank you all for the responses and information. I will utilize the 16 foot diameter curves. It will take more space and fill/rocks (I am elevating it all by approx. 2 feet) ... but I have been convinced that is a better option.
Thanks. Bob


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