HO Track Spacing?

[oryan_dunn]

I'm planning an HO layout and I need to know what a good double main spacing would be? Currently, we're planning on using atlas track and they conviently have 22" and 24" radii curves, which fit well when using thier No 6 switches for crossovers. Is this too close for stuff like the 85' passenger cars or the cars of the Acela? We'll probably end up using flex if this is too close. Thoughts?

Thanks,
Ryan

Edit:
I've looked at the NMRA pages and thier charts for this subject, but they don't seem to make much sense. What is the degrees of curvature all about? Why would it make a difference if I'm going only 40 degrees vs 45 degrees around a curve of a given radious. And the given radius, is that the inner or outer radius? Looking at that guide, it seems like I"ll need more than 2" track separation in any case. Should I jump to three inch, or something inbetween the two?

[Javern]

2.5

[Pennsy58]

The radius is simply a different method of expressing the turn of the curve. You are familiar with a 22 " radius. That means that if you stretch out a string from a point to 22" long and scribe an arc thats where the track centerline will lay.

The degree thingie has always been confusing. This relates to curvature also. If you start at a straight line at any point in the middle of the track then head off at a tangent
(angle) this will be the offset or the curvature of the track. Much harder in my little world to deal with or spec out.

Just what you were looking for eh, a refresher geometry lesson. Anyways. I originally layed my track at two inches apart on a 24" curvature. Ran into problems with long passenger cars and husky stack cars. Called out the MOW crews and relayed the track at 2.5 inches apart from the centerline and all is well so far.

Although arguable I'm sure, to avoid any problems with long cars or big steamers, I went 24" on the inside line. Then to lay the outside line I used flex track and checked the distance every couple of inches and tacked it in place. So, in essence, the outside line would be a 26.5" radius on the centerline. Now on both lines, no more problems with a 2-10-4, an SD80MAC, or long heavyweight passenger cars.

Lastly, at these radii it is slightly wider than 4 foot sheet of plywood if thats what you are using for your layout.

[IRONROOSTER]

Part of your problem is that the NMRA recommends a minimum radius of 32" for your 85 ft passenger car. see http://www.nmra.org/standards/rp-11.html for curvature recommendations. The track center spacing standard http://www.nmra.org/standards/s-8.html says that your full length passenger cars are class 1a and that line in the HO table doesn't go smaller than 32". The recommendation at 32" is 2 1/2 inches.

There are two factors at play here. One is the overhang to the inside of the curve of the long passenger cars and the other is the overhang to the outside of your locomotives, especially articulateds. When the passenger cars are on the outside track and the overhanging loco is on the inside track is where you'll have a problem. You might want to set up a curve and see how your equipment will works. Otherwise I'd do at least 2.5 inches, more if a big boy is in your future.
BTW don't forget to allow clearance on the curves when placing scenery and buildings.
Enjoy
Paul

[Anonymous]

Man, what kind of layout room does he have? 14 feet? He must be modeling in 1:1 scale. Now THAT's a hard core modeler.

[rogerhensley]

You're making it too tough. If you look just below the curvature, you'll see radius in inches. Class 1a centers does only go as low as 32 inch radius and gives 2.5 inches for the spacing. In most cases, that will work down to 24 inch radius, but you would need to test below that.

In my case, I have 21 inch radii and I'll guarantee that I never run long cars over 60 foot side by side on the curves. Far too much overhang. I would have sidswipes and derails all over the place. My little people won't grant a Train Order that would allow this to happen. My passenger special runs clear track when it moves. :-)

[cwclark]

2 1/2" center to center in curves and 2'" center to center on straight a ways.....chuck

[Anonymous]

I use 2" centers on mainline straightaways and using easements go to 2 1/2" on my curves. In one yard I brought the centers down to 1 3/4" which looks excellent, but makes rerailing a car with cars beside it impossible. Since there are never any derailments here though it is OK. Yea, and the cubs just won the world series LOL!

[johncolley]

I have some drawings of GN trackage and the most common center distances are 13 feet and 16 feet if they need crews to walk between the tracks( ie: switchmen, car inspectors, etc). Then comes 20 feet. In our HO world 13 feet does not allow for 0-5-0 switching (the big hand from the sky).

[rexhea]

QUOTE: Originally posted by cwclark

2 1/2" center to center in curves and 2'" center to center on straight a ways.....chuck

[#ditto]

Everyone talks about passenger cars, but the articulated engines will really swing wide and you need to always consider them if you use steam.

REX

[Budliner]

my two track pike as a funny problem wish I left more room for the legs of my portals



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