track spacing

[rtesta]

long time listener,,, first time caller...
looking for some quick advice on the spacing of tracks on 24"-30" radius curves, HO.
i have to run two parallel tracks through a limited space behind some steps and trying to keep it close to 6" wide, but want to keep the option open to run some reletively long equippment w/o worrying about passing through this area one train at a time.

What is a safe track center spacing?
What is a safe outer or max width i'll need not to bump the walls

i'll go mack to NMRA and look at the HO scale "template" but the adivce here has so much more insight.

now that your flattered, thanks for any advice,,, bobt

[ndbprr]

Use 2" on straight track and 2 1/2" on the curves and you should be able to handle 85' passenger cars with no problem. If you want to experiment to make it the absolute minimum lay a piece of flex track to the smallest radius and put a piece of track on the outside. Your area of contact will be where the middle of the outside car hangs to the inside of the curve and the end of the car on the inside track hangs outside the curve. As long as there is a gap you are ok.

[hoscalelarry]

Bob,
I agree with Norm, going 2 1/2" on the curves gives you 3 1/2" outside of center line to wall. Going 'off center' with track into your opening and allowing the greatest distance from wall to the inside should give you the nedded clearence. Norn, has the right idea, take a little extera time in first testing it outside of area and you'll save all sorts of time later after all is built.
Larry

[rrinker]

I got news for you - better TEST! I too was under the belief that with a 32" radius curves, 2 1/2 inch spacing on the curves would be PLENTY for 85' passenger cars. Luckily, we tested it out first!
The critical spot seems to be when the car on the outside track has just fully entered the curve (trailing truck is JUST intot he cirve) and another car starts to enter the inside curve.

--Randy

[IRONROOSTER]

The NMRA page http://www.nmra.org/standards/s-8.html doesn't cover curves as sharp as 24-30" for the longest cars (89ft). They show 32" radius with 2 1/2 inch centers. This would indicate that you will need something more than 2 1/2 inches for 24" - 30" radius. As others above have suggested better test first.
Enjoy
Paul

[Anonymous]

When in doubt, add a little more clearance to avoid problems. If everyone SAYS you need 2 1/2", I'd go 2 3/4" or 3". An extra 1/2" clearance between tracks probably won't make that much of a difference in your construction?

I'll have a double-track curve (several) on my new layout, and I'll be up close to 3" center-to-center on 28" curves that'll be eased.

Mark in Utah

[ericboone]

http://www.peremarquette.net/track-clearance-chart.xls
You can use this spreadsheet if you want. Note that the raw data should be entered in prototype dimensions and the right most two columns produce HO scale results.
See http://www.peremarquette.net/design-tools.html for an explaination of the calculations.