# Curve radius question



## Walman (Dec 18, 2011)

Please see my VERY poor drawing attached. I have a couple of curve radius questions for a planned N scale shelf layout. My goal is to have the tightest turn radius possible allowing for the most realistic look and feel while minimizing limitations for cars and engines. Please note the loops are not to scale with each other or anything else. Also for point of reference overall the shelf layout will be 24” in width and 15’ long but at both locations of these loops I will have 30” of depth. If it matters I am planning Atlas Code 55 track.

In scenario #1 I have a track simply looping around a small town and crossing back over itself. I don’t note it on the drawing but the “bottom” of this loop is near the front edge of the benchwork but the “top” of the loop will need to leave some room for a very narrow edge of scenery/backdrop and a single track mainline that is not part of the town loop/scene. Depth here can max out at 30” but would like to be more like 24”. What would you recommend for turning radius? Obviously the more room for the town the better. 

In scenario #2 I have an inner and outer loop. The loops are draw roughly as I would like them to turn out based on scenery and industries I have planned (thus not symetrical). I will definitely have 30” of depth here to complete the loops. Recommendations on the maximum radius of the inner and outer loops while accomplishing the goals I set above? 

As you can tell I am just not familiar enough with the curve radii to know which ones give me the best balance between tighter turns yet good performance (operating and visual) for the widest array of cars and engines. Any general comments would be greatly appreciated.

Thank you!

Walman


----------



## Brakeman Jake (Mar 8, 2009)

The key word here is compromise.Curve radiuses are dependent on what you'd like to run on them.The wider the curve,the wider your rolling stock selection can be.OK...here it is...

9 3/4-10 in.:about the tightest curve you can have in N scale.It will allow four axle diesels and only the shortest steamers (0-6-0's,4-4-0's,Shay's,Mogul's,etc).Forty foot cars will also look right but six axle locos and long 85 ft. cars will have a hard time and look awkward on such a curve.

11-12 in.:a big improvement but still somewhat limited.Six axle locos and long cars will do fine on these though they'd look better on wider curves.And you've opened the door to slightly bigger steamers like 2-6-2's for instance.Athearn say that their Big Boy can handle a 12 in. curve but it certainly looks terrible at it.

14-15 in.:you can have any diesel you wish along with any railcar.However,15 in. is a minimum for a few rigid based eight driver steamers like 2-8-4's,4-8-2's and 4-8-4's.Locos with 2-10-0 and 2-10-2 configuration may require even more.Many N scale articulateds (2-6-6-2's,2-8-8-2's,Challengers and Big Boy's) can handle fourteen inch radiuses but sixteen and even eighteen inch will have them look so much better.

Needless to say,if you can afford the luxury of having even larger curves,then go for it.You can't have a too large curve and the layout operation will look much more realistic.You'll be able to run longer trains too.


----------



## NIMT (Jan 6, 2011)

Walman,
Use flex track to get this all done! Any other option will have you going here there and everywhere with the track and radius's to make it work!
I do not thing your #1 will work in the space you've provided, to small a radius would create to steep a grade to obtain track clearance on the grade before the track crossing. you could stretch it out to an oval to get the needed run time on the grade to make it work.


----------

