Im starting to lay track I am using Atlas 100 #6 and #8 turnouts in
HO. I am making crossovers between 2 mainlines.
My question is what length of straight do i need to put between each turnout to have enough space between the mainlines sufficient to clear?
Thanks
Nothing…Directly connecting the diverging legs together will give you 2 inch spacing.
Nick
i have no atlas switches but every crossover i ever made with shinohara number 6 switches requied me to trim the switches back on the diverging route to keep 2" track centers.
if you know how far apart you want your adjacent tracks to be, then just plop the switches down so the rails line up without a kink and you will see whether you have to lop a little off or add a bit of extra rail. don’t forget to allow for gaps in the rails in the middle of the crossover.
grizlump
To expand the preceeding post:
If your parallel tracks are on 2 inch centers, connecting the two diverging routes of a pair of like-numbered turnouts is all you need to do.
If you want greater than 2 inch spacing between centerlines, multiply the space over 2 inches by the frog number to get the length of ‘plain-Jane’ track between the turnouts.
Chuck (Modeling Central Japan in September, 1964)
Atlas turnouts don’t have all that extra runout on the diverging route, as the other poster said, just mate them back to back, perfect 2" track centers.
I never have understood why Shinohara and others have that long runout on the diverging route? Seems you have to cut it off most of the time. Crossovers, passing sidings, yards, its always too long.
Another reason why other than hand layed, I prefer Atlas.
Sheldon
This works for the customline switches, but not for the superswitch, same issue as the Shinohara mentioned above. Keep in mind that a cross-over is an “s” curve. Adding straight track between the turnouts (while increasing track to track spacing) can help avoid issues with long rolling stock etc. Test to make sure.
True, but using a larger frog number is better than increasing track spacing. And this is another reason why Atlas turnouts make for better crossovers than the older Peco products. The Atlas have correct North American geometry so all the curve is before the frog so that on a crossover there a straight section between the two curves. The bigger the turnout size, the longer this straight section, minimizing the “S” curve.
Sheldon
Sheldon, as I said, test to make sure. My 85ft passenger cars seem to negotiate No 8 and No 6 Atlas based crossovers without derailing with the 2in track spacing.
Of course, club standards and “free-mo” seem to insist on straight sections.
hi,
Most brands of switches are constructed with a “curved” part before the frog and a straight part beyond the frog. In a crossover both straights together have a considerable length.
When pulling coaches a #6 crossover will do nicely, even with 90 feet coaches or autoracks. Overhang and coupler mismatch will be considerable; you might not like the looks though. Most of the time passenger train coaches have about the same length, which also helps to prevent derailments.
More spacing is making the straight part longer, so the length of your crossover, but a lot less then you would need for a #8 crossover. I do not know club or freemo standards, if you want your straight part as long as your longest car you will need a lot of track centre spacing; over 3"!!.
Paul
There’s no need to add a long straight between the turnouts of a crossover. For most applications, a crossover made of #6s or larger will be adequate.
There’s also no reason to be limited to the “natural” track-to-track spacing that comes from placing the turnouts together. Choose your track-to-track-spacing to fit the situation, and then trim or add track to make your crossovers conform to this.
The NMRA standards for track-to-track spacing are a good place to start.
Byron
I’m glad someone else pointed that out. Many of us old timers forget Atlas has expanded the line. Many of us really old timers remember the days BEFORE the customline switches which also had the same issue.
Which is 2 1/16 for yards (minimum) and 1 13/16 on parallel track (what is that scale 15ft?) which, as John Amstrong said, looks better.
Not exactly. That standard sets out different track-to-track spacings for different curve radii and for different sizes of equipment. Often, one will need to carry over a wider spacing from curved track into adjoining straight sections for various reasons, so HO track-to-track spacing is not the one-size-fits-all you seem to be suggesting, in my experience.
But perhaps I do not understand your point.
Doc, I just have to ask - what does this mean? I know what free mo is but have never examined their standards.
As for clubs, what clubs where? Every club I have ever seen, been a member of, or known much about had different standards - some very NMRA guided, some not.
Sheldon
There’s no exactly right answer, btw. If your mainlines are a different space apart, you may have to set your turnouts further apart and put a spacer in between them. Put your turnout that is most critical in place first, and then make the diverging track on both turnouts line up by sliding your 2nd turnout along the mainline until you can look straight down the diverging track and see it line up perfectly with your 2ns turnout.
Or, if your turnouts have a longer track on the diverging route, you may need to trim the track. Again, place the more critically spaced turnout into your mainline first, and then slide the 2nd one up and down the mainline until it lines up perfectly. Now trim you diverging track on one or both turnouts to fit.
Some examples I have come across:
From the Free-Mo Standards:
S3.8 Turnouts shall be at least #6.
RP3.8.1Turnouts on the module through route should be #8 or larger.
S3.9 There shall be a minimum of 12 inches of straight track between reverse curves.
Meade Area Railroad Society (MARRS) Smart-N Module Standards:
3.2. Curvature
The minimum radius for the mainline is 17.00". Recommended: No curves of less than 11.00" radius should be used. All mainline curves of less than 19.00" radius must begin and end with either an appropriate easement or a 15-degree curve segment of 19.00" radius.
All S-curve situations on the mainline must incorporate at least 4.90" of tangent (straight) track between the curves.
Baltimore OneTrak Group (BOG) Module Standards (N-Trak based):
5. MINIMUM RADIUS - is 18 inches with appropriate easements. To prevent binding the minimum length of tangent between all reverse curves must be 7 inches.
NMRA ROCKY MOUNTAIN REGION MODULE STANDARDS (HO)
“4.1.14 “S” Curves
All “S” curves must have a tangent section of track 90 scale feet long between the two curves. The
minimum radius of the curves shall be 32 inches.”
They’re not talking about the short reverse curves in crossovers created by turnouts between parallel tracks. That’s obvious from the descriptions.
Doc, I have to agree with cuyama here, none of those standards would seem to apply to crossovers to me.
But, since I’m not a “club joiner” or a “module builder” it matters not.
Since it has become such a discussion, I will share where my 40 years of building model trains has left me on the subject of parallel track spacing.
I am well aware of prototype dimensions and of NMRA RP’s, but I have found that for my purposes, a universal 2" spacing works well for the following reasons:
One, the reason that started this thread, the easily assembed Atlas #4.5, #6 & #8 crossover. And, the similar easy assembly of yard ladders with those turnouts.
Two, the large number of commercial products (bridges, structures and other track items) that use 2" or something very close to it.
Three, it is close enough to look good and wide enough to allow handling the equipment if needed.
Four, it keeps things simple.
Five, at the large radius curves I use, 36" and larger, no additional spacing is needed on curves.
Six, It is easy to do with commercial roadbed like Homabed.
As mentioned I use large curves, 36" in my minimum. All cuves have easments. And even with such large curves, I avoid really long equipment and locos.
Sheldon