Great article

And one that gives a far more relevant meaning than the old "sharp, conventional, and broad" curve descriptions.  Those were good for their time, when flextrack was in its infancy, and many layouts featured bowl-of-spaghetti track configurations.  Since the dominant freight car in those days was the venerable 40-footer, it seems that they were on the right track.  However, as freight cars grew, so did the minimums needed for reliable operation.  Passenger cars were always a special needs population as far as our model empires were concerned.  A couple of the railroads I operate on have passenger operations, with most (if not all) of their switching taking place on straight track.

I look forward to more articles like this, Joe.  It's an exciting time be be a model railroader.

Very timely article for me

Joe,

Since I am currently immersed in planning our layout this is very timely information.  Thanks for a great article!

Armed with these simple rules and the insights I gained from Tim's article on S-curves I feel that much closer to being "qualified" to plan my layout.

Thanks again!  As I expected the first issue has blown me away.  I brought my wife and son over to the computer on a number of occaisions today when they heard me exclaim, WOW!  The whole family has enjoyed looking through issue # 1.  I'm the only one in the family that even turns a page in the print mag I get regularly.  That says something for the power of rich interactive media.

Pics were nice

I had read about the ratio method before but seeing the photos illustrating through example was very nice. I think too often guidelines are given without providing "real" examples of why the guideline is in place.

Chris

Article draws similar conclusions to what I use.

Last year the Australian Model Railway Association (AMRA) adopted a minim radius standard based on a series of formulae. For bogie vehicles the AMRA standard used 3x the length as the recommended minimum radius.  An excellent article that confirms the assumptions used in the AMRA  standard are valid.

Terry Flynn.

I found the article on

I found the article on projecting curve radi very informative.  Very interesting to know you can actually compute radi based on your car length.  Good info to have.  Thank you for a great article.

Terry in FLorida

Excellent article

I have to thank you for your time and effort that you put into this great article,your description is just plain "EXCELLENT" and very clear photography.

I have also taken some of the plain-jane Locos and converted them to take the decoders with sound. Had good luck with them.

Thanks again.

James.

Curve Radius Design Considerations

Wow!  Another outstanding article that really "shows" what the standards define.  Timely too, as I am planning a major expansion of my European layout this year.

David Martin, Ph.D.

Best article in the issue

Best article in the issue IMO.  I would like to see a similar approach taken with easement curves.  Would be a good follow up to this I think

Easements

Formula one model railroading

Joe Most excellent work on your part. Just as I have supected for years thank you for doing the leg work and the math. It is a very good way to guesstamate how a plan will operate. Another formatable tool to add to the tool box of model railroading.

Curve Radii

This is indeed a very timely article. Without even knowing it I've used this method before, when planning layouts, just never knew what it was called. IIRC they were discussing this a long while back on the LDSig.

CJ

Curves, Easements and Superelevation

Joe,

A great article!  A follow-up article on easements and superelevation would be equally helpful with a particular focus on the length of easements, the length of the transition from level to superelevated track, and the amount of superelevation that is appropriate.

curves

Joe - I cannot believe how simple that seems to be - but I can understand it and thanks to you for making it easy to understand, as usual.

The magazine is a success for me right off the bat, and I had to download it in a marina deep in Guatemala. Thanks for keeping me occupied with trains instead of the work of my sailboat.

Cheers, Jake

Curve radius insights and steam engines?

This article cannot be applied directly to what track curves/radii a steam engine can be expected to navigate, i.e. the engine without it's tender. With engines such as 0-6-0, 2-8-0, 2-8-4  and 4-6-4, one is not concerned about coupling but with what curves the series of 6 or 8 fixed wheels will navigate.

Could there be a similar kind of calculation that would apply to curves various steam engines can be expected to navigate?

Malcolm Horsnell (Modelling the Toronto Hamilton & Buffalo Railway)

The rigid wheelbase is the issue

I'd expect you will want to measure the length of the rigid wheelbase of any steamer and then probably go for a 4x factor to have minimum issues with binding, etc on the curve.

Of course it gets more interesting with things like articulated locos, since they may track well on 4x of the rigid wheelbase, but they will look like heck.

So for looks, the length of the equipment guideline still applies. 3.5x of the loco's actual length will look decent from inside the curve, 4x will look decent from outside the curve - and at 5x the loco will couple just like on straight track.

Locos, because of the mechanism tied to the wheels, are something of a special case. You should always test out your locos on various curves before  you commit yourself to that 20 year dream layout project only to find your favorite loco won't run worth a darn on that minimum radius!

Compact reference on LDSIG Wiki

IIRC they were discussing this a long while back on the LDSig.

The results of that collaboration are still up on the LDSIG Wiki (also maintained by our host Joe F) and are a good compact reference to complement the visual article in MRH.
Curve radius rule-of-thumb

I felt that was the best

I felt that was the best article in the issue as well.

Nice work, Bone Daddy!

Another issue with steam

How many of the drivers are "blind" - where they don't have any flanges? The more blind flanges, the tighter the radius (and probably the more ridiculous looking, but there you go).

 As I understand it, even prototype locomotives had blind drivers.

very useful data

These guidelines are going to come in very handy in planning "aesthetic" vs. "reliable but tight" curves on a layout.

For my predominantly 40' cars, I can use the 5x (37.5") radius for the visible (& switching) sections, and stick to 2.5x or 3x (18.75" or  22.5") radii in the secondary (& hidden) areas. Should I ever want to realistically run 85' heavyweight passenger equipment, I know I should be planning on 63.75" (4x) radius or greater.

I'd better plan on a larger house purchase; I'm going to need 12' of width just to turn a passenger train around

curve ratios

Solved my planning issues ... I will replan my project for apprpopriate curves ... doing Amtrak N-scale passenger sercice between Seattle, Edmonds, and Everett. Cars will be +6" so I'll look at 5.0, 4.0 and 3.0 for my staging/holding pen. Don't need to switch/decouple on curves, but trains may be double ended to simplify operations.

Great article--leads me to your supporting adveretisers.

Bill, Edmonds

Is all that simple?

Hello Joe,

firstly, a very interesting article with clear explanations and useful pictures.

Second, is that so simple? When I ended reading your article I thought: wow it's totally straightforward I should have got to the same results If only I were smarter than I am.

A really nice way to establish the behaviour of cars on a given curve before buying the first piece of equipment and in addition totally scale-free.

Third, it came perfectly on time for me since I'm starting to plan my first layout and I'm eagerly looking for as many info as possible. And this article is going to be a reference for me.

Regards, Ricky4208.

P.S. as many other have written it would be nice do follow up with other articles about easements, superelevations and all that is related to what you can to in order to predict beforehand how you equipment will perform.

 

This article makes me feel a

This article makes me feel a lot better about some things in my track plan. Salmo BC may yet have passenger service!

Reasonable compromise or faulty thinking?

Thought the article on curve radius guidelines was quite eye opening!

I'm in the process of designing a new HO layout and am severely limited by an 8' room depth (20' long). I'm modeling the C&NW in and around Chicago and one of my "givens" is running bi-level 85' commuter cars. As much as I'd love to have 40" radius curves that ain't gonna happen!

So, here's my thinking - since these cars would only be viewed from inside the curve (it's going to be an around-the-walls layout) could I minimize the downside of a smaller radius by increasing the layout height?

My thinking is the lower the layout height the more pronounced the car overhang would be perceived.

Make sense or not?!

Chuck

Chuck, great application!

Chuck:

Yes, that's a great application of the curve radius guidelines, plus the value of high benchwork. You can drop to about 3.5x and view the curve from only the inside at about armpit height and your commuter cars should look reasonably okay. However, as I illustrate, they may need coaxing to couple, and any diaphrams may not mate perfectly.

I find expressing curve radius as a ratio of rolling stock length suddenly causes the whole radius question to make much more sense. And if you relate it to how the rolling stock looks on the curve, and how well things couple on a curve - you're now considering all the proper variables that need to be considered when deciding on a minimum radius.

And your point of getting the track level higher also works as a visual trick to allow sharper curves, especially when viewed from the inside.