I've acquired a lot of 2205 flex track. I'm planning a somewhat permanent layout. In the meantime, I've had a lot of fun experimenting with discovering the "ideal" curve/radius for what Märklin in its 2010 catalog calls "sweeping" curves. This is of course a completely subjective quality. At the moment, I've decided it is exactly 1.07 meters or 3.5 feet! I have more space than that if needed, up to 1.83 meters. But even my longer trains don't need any more than a 3.5 foot radius to look sweeping, prototypical, and beautiful. What do y'all think? If you had all the room in the world, how big would you make your curves? I was surprised at how narrow the window was for my own idea of perfection. 3.5 feet was JUST RIGHT! Reminds me of nature's golden mean and perfect ratio, etc. Also reminds me of actually riding passenger trains all over Europe from 1958 to 1968. A long train on a long curve is a very graceful thing to behold.
Regards,
Tommy

IMHO, that is not the 100% right way to look at it.
OF COURSE you should make the curve as big as your space allow it, but MUCH MORE important is it to use EASEMENTS on the entry and exit of the curve.
It is the gradual curvature of the track that makes the trains go "beautifully" through the curves.
There´s nothing nice about a train travelling at 160 scale km/h, going from straight track and directly to an R-1m curve!
WIth easements you could even go through an R-80cm curve in around the same space, and it will look better. (Try it...)

Hi
The best and most prototypical is the "parabolic" curve.
On model layouts we can only suggest this and IMO the best is to hide the sharp cuves (under tunnels, with trees).

Cheers
Jean

Hi,

Some diversion from the topic, but regarding "clothoids" it is true that it is used sometimes in road construction. I worked at the Swedish road administration for some time, many many years ago. The "clothoids" were mainly useful for entrances to highways. The radius increases the further you get. Then, when you accelerate out onto the highway you get an almost constant centripetal force, which feels nice.

However, on highway exits, they were not used. There, you had a sharp radius directly. The reason was that the "clothoid" would fool the driver to think that he/she could take the curve in too high speed. So it was dangerous. Sweden changed from left-hand traffic to right-hand traffic in 1967, and then the highway entries became exits and vice versa. It resulted in a lot of accidents where people ran off road at highway exits, so they had to change the exits. In the 70's when I worked at the road administration there were still some highway exits that weren't fixed yet. I was very close to going off road once myself in such a place, I slipped on all 4 wheels but managed to get control over it. Now it is fixed everywhere, I think.

Regards
Per

A simple way out to find good curves are to use same curve radii like long turnouts 22715 and 22716.
The turnout 2265 and 2266 do have same curve radii like 2231, but i see those curve radii are still too narrow.
So for me i believe the curve radii are best at least 900 mm!
With that of the curve radii you have close to realist traffic like prototype.

The Maerklin R9 curve radius measures ca. 97 m in the 87/1 world.

According to current standards, minimum radii in Germany are:
300 m on a main line;
180 m on a branch line where main line equipment is expected to operate;
100 m on a branch line, where no main line equipment is expected to operate;
35 m on an "industry switching spur".
For the latter, precautionary measures are needed regarding construction and maximum speed.

Source: http://www.gleisbau-welt...vermessung/geometrie.htm

And some more info by forum member Tom aka H0:

Great subject. Its really got my curiosity.

Alsterstreek, are you able to check the address here Source: http://www.gleisbau-welt...vermessung/geometrie.htm As it is not available from my end.

Dereck

It is indeed difficult to navigate on that website, which contains a nice overview, but I also cannot retrieve the table right now. Anyway, art. 6 (1) of the German Eisenbahnbetriebsordnung (EBO) stipulates a minimum radius of 300 m on main lines and 180 m on branch lines:
https://www.gesetze-im-internet.de/ebo/__6.html

I think you're arguing with yourself here, and not really getting to the point of the argument

Per.

You split word sentences by deviating on what the thread is about.
The thread is about what is the most beautiful radius for the model railway.
Märklin is known for making track curves too tight so that it deviates from after prototype track laying.
Even carriages (Märklin 28,3 cm) are not scale imaged correctly in length, precisely because of tight curves.
Märklins track curves 2221, 2231, 2241 and 2251 are not correct scale and not even beautiful curves while 2274 it does get close to prototype for the curves.

How many of you have not complained about tight curves in connection with train problems?
TS asked a question about what is your most beautiful curve radius?
What is yours?
I did wrote about 900 mm which are ideal.

I would like to post this picture and my highly subjective analysis.



Note the inside 'radius'. Marklin designers made this curvature so that 'table top RR' could actually fit on a dining room table in most homes. I know that in my home in the 1970's during the Christmas Holiday season, our dining room table was pressed into special RR service. The Crocodile locomotive can actually run on this tight inner track.

If I had more space, I would have included sidings, a rail yard, a decoupler area, all of it.

I have been told by 'experts' that Marklin engineers had to play a few tricks with the HO scale to allow for the tight inner curve.

Marklin, they allow you to use your imagination to its fullest!

For me, the 'Most beautiful radius' is the one that your train table space allows.

For my ideal 'Ultimate' setup, I would make a layout 4 times as large as the one above, have 4 or 5 rings of tracks with a rail yard in the center. I have seen videos of layouts with intersecting tracks, Local and Express lines, along with freight lines, all under automatic control of switches. It can run for hours without head on collisions (my attempt, first 30 min had a head on collision!)