Smallest prototypical curve in HO?

[RobertInOntario]

Just wondering what the smallest prototypical curve is in HO? Is 18"R too tight to be realistic?

At this stage, I have no choice but to use 18"R and even 15 to 17"R curves (due to lack of space) but it would be nice, one day, to have more realistic curve radii on my layout.

Thanks,
Rob

[nachoman]

I remember investigating this a few years ago after looking at some industrial trackage that I thought had very sharp curves. After looking at the area on google earth, I learned the actual radius was something like 300 feet. That comes out to be about 42 inches in ho scale. So, I assume the sharpest prototypical scale curve would be about 40 inches in HO.

The Uintah railway was 3' narrow gauge, and had some of the sharpest curves in the USA. I remember calculating they would scale out to be about 14-15 inches in ho scale. Remember, this was narrow gauge with specially modified locomotives and cars. They used shays and articulated locomotives only on that part of the line. I suspect some logging lines had equally sharp curves, but these were special cases.

Nobody has prototypical curves on their layout. The best you can to is use the widest you have room for, and try to hide the curve so that you can't see the whole thing at once. I am using 18" for both standard and narrow gauge because that is all I have room for. I am trying to make the sharp curves less noticeable by hiding parts of them inside tunnels.

[Selector]

Transit system radii would run down to as low as 11" or so in HO.

[MasonJar]

The Credit Valley had curves in its narrow gauge days that were on the order of 700' radii, and these were described in print as "tight". That works out to about 10' / 120" radius in HO...!

But transit curves are probably the tightest prototypical. Out at the Halton County Radial Railway museum, they have a turning loop that can't be more than 60 or 70 foot radius - that's under 10" in HO.

Andrew

[RobertInOntario]

The Credit Valley had curves in its narrow gauge days that were on the order of 700' radii, and these were described in print as "tight". That works out to about 10' / 120" radius in HO...!

But transit curves are probably the tightest prototypical. Out at the Halton County Radial Railway museum, they have a turning loop that can't be more than 60 or 70 foot radius - that's under 10" in HO.

Andrew

Thanks, Andrew. I was just thinking of those HCRR loops as they certainly are tight! Their streetcars will go through them but not their larger interurban. Cheers, Rob

[RobertInOntario]

I remember investigating this a few years ago after looking at some industrial trackage that I thought had very sharp curves. After looking at the area on google earth, I learned the actual radius was something like 300 feet. That comes out to be about 42 inches in ho scale. So, I assume the sharpest prototypical scale curve would be about 40 inches in HO.

The Uintah railway was 3' narrow gauge, and had some of the sharpest curves in the USA. I remember calculating they would scale out to be about 14-15 inches in ho scale. Remember, this was narrow gauge with specially modified locomotives and cars. They used shays and articulated locomotives only on that part of the line. I suspect some logging lines had equally sharp curves, but these were special cases.

Nobody has prototypical curves on their layout. The best you can to is use the widest you have room for, and try to hide the curve so that you can't see the whole thing at once. I am using 18" for both standard and narrow gauge because that is all I have room for. I am trying to make the sharp curves less noticeable by hiding parts of them inside tunnels.

Thanks, Kevin. At a MRR show, I once saw a very long narrow HO layout that had sharp (possibly 15"R?) curves at either end. The guy who made the layout had covered either end with tunnels so you couldn't actually see them, but there was lots of RR detail to see in between. Cheers, Rob

[e-paw]

The CNJ's Bronx terminal had some realy tight turns. I don't know what the #'s were but they were tight. There box cab and 0-4-0 that worked the terminal had modified couplers to negotiate the turns, and I believe that no freight cars over 40 feet could enter the trackage there either. Some one at the other site was doing a real nice job building it in HO. May be you can check with them.

[Squidbait]

There were actually several transfer terminals in New York, laid out similarly to the CNJ Bronx terminal.

The DL&W Harlem terminal had curves of 90' radii, although they had to widen the gauge 1/2" to 4' 9" to accomodate the sharp curves, and add an extra link in the coupler chain to let the cars get around. That's roughly 12.5" radius in HO

[Ralph]

I'm glad you mentioned the Bronx Terminal trackage Squid...that was the first thing that popped into my mind after reading about them a year or so ago.
Talk about tight curves!
Ralph

[Squidbait]

I can't take credit for bringing it up first, that was E-Paw.... I just elaborated a bit.

[BR60103]

I paced off one of the streetcar intersections in Toronto and the inside curve seemed to be about 50' radius up to the switchpoints. That's one of the reasons TTC is having problems ordering off-the-shelf streetcars.
I have a book that gives some minimum radii of locomotives. I remember numbers like 700-900' and that is travelling dead slow in the shops area. I also noted that articulateds had sharper curves than regular locos.

[Will_Annand]

The Credit Valley had curves in its narrow gauge days that were on the order of 700' radii, and these were described in print as "tight". That works out to about 10' / 120" radius in HO...!

But transit curves are probably the tightest prototypical. Out at the Halton County Radial Railway museum, they have a turning loop that can't be more than 60 or 70 foot radius - that's under 10" in HO.

Andrew

Andrew, I hope you are refering to the region when you mention the Credit Valley's marrow gauge days.
The Hamilton and Northwestern Railway, as well as the TG&B were narrow gauge.

The Credit Valley Railway itself started life as the first standard gauge railway in ONtario.

[MasonJar]

Ooops! Thanks WIll.

Ahem... yes... I was, er, referring to the region, and of course we all know it was indded the TH&B... er TG&B that was the narrow gauge line in its early days... :oops:

Andrew

[jbaakko]

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