Ideal Curve Radius

What is the minimum ideal curve radius for passenger cars? I’m building a layout in my basement and my mainline minimum radius is 40 ".

24" is the minimum for operating full legnth passenger cars and 36"(?) is the ideal. You should be fine for all equipment on your layout.

soumodeler

The Southern Serves the South!
http://www.trainweb.org/mgr

I beleive the ideal radius would be 120’’ radius with super evevation.

But in your case just about anything will run on 40’’ with no problem.

I would love to see a layout with a minimum raidus of 140". It would be huge.

With a 40" minimum radius you should be in great shape. Full size (85’) will make it around 24" curves OK .
Have Fun,
Tom Watkins

You should be able to run cars with diapraghms at that radius also.

40 inches is huge in N scale, really nice for HO, about usual for S, or On3, and tight in O-standard, and REALLY TIGHT in large scale #1. Not everone here is in HO, just almost everyone… so that’s my silly 2 cents worth as an O scaler

True for plastic, not completely detailed cars. With complete detailing, or many of the brass cars, 40" will probably by okay for a minimum.

Hello ? [%-)] But what scale are we talking about ? [%-)]

As Jennifer RR says …

When giving measurements, could you please remember to indicate in what scale you are working ?[:)]

Here is a thought that has nothing to do with scale. Look at photographs of the real thing. Then ask yourself regardless of scale …can I get 10-12 cars on a 90 degree turn? six to eight is good. anything less looks toylike. I am in HO and have a 45 degree with easements, 72"radius curve that my streamliner just flows around a river bend.

As large as possible for your availible space.
The gentler the curve is the more realistic it looks. As said before look at proto-types, super elevation and broad curves are great elements to model.

Being a passenger freak, I once did a test on 85’ cars with various radii to find where they stopped looking ‘toy like’. It was 48"r, Since 46" fit’s on half an 8’ ply board, I settled on 4’ for 90 degree corners and talked myself into not noticing any difference’s.Semi-triangulating these corners revealed how little room these 4’ corner section’s took up.

I ended up with 10’ X 18’, easement’s and super elevated curves, all reachable from the INSIDE - and using up less floor space than a 4 X 8 when you count the walking around room it takes up. My 5 X 10 Ping Pong table required more room!.

In terms of ‘running’ it seems most things will run on 36"r , but that’s due to the skill of our model maker’s - knowing what dimension’s to cheat on, what to leave out, etc.

THAT being said, HO equipment will RUN better as well as look better on 46" + curves - unless, of course you prefer it looking ‘Toy Like’?

We all have our grand dreams of wide sweeping curves.For some this is possible.For others like me then I use the largest curve possible even if its a 24" curve.Heck,even the club layout the curves are only 30"…Of course then there is that slow speed “S” curve of 26".Thankfully we have no problems running long wheel base locomotives and cars thanks to the manufacturers foresight in designing their products.[:D] So with your curves of 40" you have no worries.