Curve radius for dogbone turnarounds

[Jacob Z]

I'm planning for my first layout in 40+ years, and looking at a dogbone plan*. I've read lots of posts on minimum/recommended curve radius and didn't find too much consensus, so wanted to get some expert opinions, in particular for the turnarounds at each end. I'm currently thinking about steam, 1940s-ish, freight-only initially, but maybe some passenger coaches later. The turnarounds will be out of sight.

- what do you all recommend for the radius?
- does it make sense to use sectional track for the turnarounds? I plan to use flex everywhere else because I like sweeping S-curves, but worry about using it for a tight-near circle.




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*I like the idea of (a) continuous running, (b) a more realistic look than a big loop, and (c) a layout narrow enough that I can reach everywhere with my t-rex sized arms

 

[bnsf971]

If you are planning to use late US steam, you would probably need to stick with 15" radius curves. I have 11" curves on my layout, and the larger steam engines sometimes express their displeasure at having to negotiate those curves.

 

[migalyto]

- what do you all recommend for the radius?

As far as radius, go with the largest you have room for!

- does it make sense to use sectional track for the turnarounds? I plan to use flex everywhere else because I like sweeping S-curves, but worry about using it for a tight-near circle.

I would use flex for the whole layout over sectional. Less joints to cause electrical problems, and your not tied to whatever is commercially available. The big reason is you can build easements in and out of the curves with flex. Your equipment will look and operate much better with them.

 

[Iron Horseman]

I'm planning for my first layout in 40+ years, and looking at a dogbone plan*. I've read lots of posts on minimum/recommended curve radius and didn't find too much consensus, so wanted to get some expert opinions, in particular for the turnarounds at each end. I'm currently thinking about steam, 1940s-ish, freight-only initially, but maybe some passenger coaches later. The turnarounds will be out of sight.

I am confused, you are talking about a dogbone plan but also about turnouts at each end. Do you mean you are doing a loop-to-loop layout? A dogbone does not require any turnouts.

- what do you all recommend for the radius?
- does it make sense to use sectional track for the turnarounds? I plan to use flex everywhere else because I like sweeping S-curves, but worry about using it for a tight-near circle.

As the others have said, you want to use the largest radius that is practical for your situation. 1940s one has mostly 40' freight cars so one could go down to 15" radius, BUT most locomotives won't like that. And if you want to add longer things later like passenger cars that needs to be calculated into the equation up front. Can't change the radius when the rolling stock changes. So you need to determine your minimum radius based on the locos and passenger cars. Walthers cars say min radius 24", but they still bind up a bit in that. I used 28" and they are doing OK.

Nothing wrong with using sectional track. I used it for one of my loops on the modular units. I believe this corner is also all sectional. Mixture of 24" and 32".

 

[bnsf971]

I am confused, you are talking about a dogbone plan but also about turnouts at each end. Do you mean you are doing a loop-to-loop layout? A dogbone does not require any turnouts.


As the others have said, you want to use the largest radius that is practical for your situation. 1940s one has mostly 40' freight cars so one could go down to 15" radius, BUT most locomotives won't like that. And if you want to add longer things later like passenger cars that needs to be calculated into the equation up front. Can't change the radius when the rolling stock changes. So you need to determine your minimum radius based on the locos and passenger cars. Walthers cars say min radius 24", but they still bind up a bit in that. I used 28" and they are doing OK.

Nothing wrong with using sectional track. I used it for one of my loops on the modular units. I believe this corner is also all sectional. Mixture of 24" and 32".
View attachment 207831

While the OP doesn't specify in his post, the thread is in the N scale section, so minimum radii would be considerably less than what it would be in HO scale.

 

[Iron Horseman]

While the OP doesn't specify in his post, the thread is in the N scale section, so minimum radii would be considerably less than what it would be in HO scale.

Yup, I missed that point. Should have know though as I see this is in the N-scale topic heading.

 

[kjd]

The first issue of Model Railroad Hobbyist had an article about curve radius and the consensus is for best operation, it should be at least 3x the length of your longest equipment.

In HO, an auto rack is a foot long so at a minimum it should have a 36” radius for dependable operations. More than that is better especially if trying to couple on curves.

Of course, there are those who can modify them to get around a 13” or some other ridiculously tight curve but the article was about dependable operation.