# Minimum Radius on my HO Layout



## PaulyWally (Oct 16, 2015)

While designing my first HO layout, I thought that it'd be best to ensure there were no radii less than 22". But I see a ton of used 18" radius curved track. It seems to be so much more common than 22" (and up).

So I'm just wondering... am I being overly cautious keeping a 22" min? Or is this a good design decision?

Thanks in advance!


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## johnfl68 (Feb 1, 2015)

Depends on what you are going to run.

If you are going to run diesel and freight cars, you should be ok with around 18" to 22" radius curves.

If you are going to run any steam and long passenger cars, then you should try to get all your curves up to at least 24" radius curves and larger number turnouts where possible (#8 to #10) especially on mainline tracks. The steam engines need a gentler curve to navigate with all the wheels.

John


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## D&J Railroad (Oct 4, 2013)

I think you are meaning 22" radii curves. 22 degree curve would be a bit wider radii, about 275' in real size wereas a 22" radii would be about 159' in real size. Either way, both are very tight radii that you would only run shorter cars on so they don't have a major overhang problem in the curve.


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## PaulyWally (Oct 16, 2015)

D&J Railroad said:


> I think you are meaning 22" radii curves. 22 degree curve would be a bit wider radii, about 275' in real size wereas a 22" radii would be about 159' in real size. Either way, both are very tight radii that you would only run shorter cars on so they don't have a major overhang problem in the curve.


Yeah. Sorry. 22" radius. (fixed)


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## MtRR75 (Nov 27, 2013)

Minimum radius is one of those areas where you get all kinds of opinions. The most common recommendation that I have seen is that 18 radius curves USUALLY work with rolling stock of about 50ft or less, 4-axil diesels, and steamers with 6 drivers or less.

However, many manufacturers of larger and longer locos make many (but not all) their locos so that they will work on 18" radius curves, because they want to sell a lot of locos, and a lot of people have 18" curves.

I have nothing but 18" curves on my 4 x 8 foot table -- mainly because I inherited this layout. I have one 6-axil diesel that works perfectly. All the rest of my locos are steamers. Most of them I bought used. I have a Bachmann Spectrum 2-8-0, three Pacifics (4-6-2) from two different manufacturers (IHC and Rivarossi), two 2-8-2s (one BLI and one Mantua), and a Rivarossi 2-8-8-2. ALL of them run on my 18" curves flawlessly. (Two of them do suffer from rare front truck derailments on turnouts, but this is due to the combination of the Atlas Snap Turnout and design problems with the front truck -- which I am working on fixing.) I also have one passenger train with cars up to 84 ft. and with truck-mounted couplers. It also runs flawlessly on my 18" curves. But if the couplers were body-mounted, it would quickly derail.

Now, having said that, there is a difference between the ABILITY to run on tight curves and the LOOK of running on tight curves. On tight curves long locos and cars hang over the edge of the track by an unrealistic amount. This is most obvious on cars or locos 60 ft or longer. This bothers some people more than others. I have decided to live with it, because I want to run certain trains, and I am willing to live with the tight curve look in order to run what I want to on my railroad. Others will make different choices.

Since you are starting out, you might be better to go for at least 22" curves (maybe 18" in the yard) -- unless it makes your desired layout impossible within the available space.


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## CTValleyRR (Jul 26, 2014)

18" curves are the ones provided with train sets, which is why they are the most prevalent. I'm using 22" and 24", which work fine for the equipment I'm running. The overhang on some of the longer equipment looks lousy, but I can live with that.


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## thedoc (Oct 15, 2015)

If you have the room use as wide a radius as possible, with model trains it's not so much what equipment will run on what radius track, (most equipment will negotiate an 18" radius), but it looks a bit silly doing so.


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## DonR (Oct 18, 2012)

I'm for the widest radius tracks you have room for. But, try to do it
with flex track. It's 3 foot length does away with so many joiners and
the problems that come with them. Plus, you can bend it
or cut it to fit YOUR plans rather than make your layout fit THEIR
tracks.

Don


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## thedoc (Oct 15, 2015)

DonR said:


> I'm for the widest radius tracks you have room for. But, try to do it
> with flex track. It's 3 foot length does away with so many joiners and
> the problems that come with them. Plus, you can bend it
> or cut it to fit YOUR plans rather than make your layout fit THEIR
> ...



The other point with using flex track for curves is that if you solder the joints as you lay the track, you will end up with smoother curves. But solder the joints with the track "relaxed" across the joint, if you solder the joint under tension you could end up with kinks in the curve.


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## Chet (Aug 15, 2014)

I would opt for the broadest radius you can. Like it was mentioned above, 18 inch radius curves are what usually comes with train sets. 

Many people with smaller layouts are confined to smaller radius curves due to lack of space. I am fortunate enough to have a lot of room available to me. My minimum radius is 32 inches, but most curves are broader, up to about 45 or more inches. 

Many people also use sectional track. I would recommend using flex track. Back in the 70's when I first got out of the service I was in train withdrawal and ended up building a small N scale layout that I could slide under a bed. Stuck in an apartment. The people at a hobby shop introduced me to flex track and I never touched sectional track again. 

When I started my HO scale layout I was hand laying code 70 track and turnouts and completed the layout using code 70 flex track. Also by using flex track, you can make transitions into curves so easily. A transition is a gradual change from straight to curved track work. Also by using flex track, which usually come in lengths of 36 inches, you'll have fewer joints which can possibly cause electrical problems. By using flex track you are not confined or restricted to a fixed radius.


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