Rookie question, I know. But I add a second loop on my layout and I need to know the gap I need at out of the turn with Atlas O-72 track, between the ties or the rails just to be clear with what we're talking about. Kind of gap to run 2 big engine like 4-8-8-4 or 2-10-10-2 locomotives. Thanxs for your help. (again!)
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Hello. I don't know what the exact minimum could be, but I believe the standard separation from centre rail to centre rail is 6" (15cm). So you would go from O60 to O72 to O84. These all have a 12"(30cm) difference in diameter, or a 6"(15cm) difference in radius. You could probably get away with a little less at the larger radii, but it's always better to be safe than sorry.
FasTrack was designed with this in mind. As Nicole pointed out, there is a 6 inch distance between center rails for each successive size of track. What I would do though is put down your O72 and then check the overhang of your engines and long cars. You may need to go wider than you had originally planned or increase the distances between the track centers.
J.C.,
On my new layout, I have Atlas Ø108 and Ø99 curves with 4-1/2" spacing throughout my dual main tracks and this allows my MTH Premier Big Boy 4-8-8-4 to run together with all the equipment I have except with the MTH Premier DDA40X. If the DD40 is on the outer curve and the Big Boy on the inner curve, they will hit. The Big Boy sticks out about 2" beyond the outer rail, and the DD40 is the worst for taking up space on the inner curves.
On page 3 of my layout thread (link in my signature, below) I posted pictures of the Big Boy and a passenger car. Unfortunately, that was in the old forum, and the picture can no longer be enlarged.
Bottom line: the 6" is probably a safe spacing.
You also have to watch for clearances for tunnel portals, buildings and other obstacles. I have found that if I use the Union Pacific recommended track clearances, everything is OK. That is, no less than 18-ft (4-1/2") total, or 9-ft (2-1/4") from center of track to obstruction. For buildings, etc., the clearance distances are greater.
REF: Page 6 of this document (link)
http://www.uprr.com/aboutup/op...ded/track_design.pdf
From here:
http://www.uprr.com/aboutup/op...cs/track/index.shtml
Good luck with your project.
Alex
On one end of my layout I have three tracks that turn on to one bridge. In order to make them fit I had to squeeze them to 4.5 inches center rail to center rail. My scale steamers make it but boy it makes for some nervous head on meets at that bridge.
It's fine for my triditional size engines but the scale stuff dose pass to close. I adjust the speed of one train so that will seldom happen, why test fate!
On the other end of the platform I went with Nicol's six inch rule and the scale stuff looks so much better at that end. If at all possible go with six inch spacing. It may not look prototypical but a truly scale turn would be about a hundred foot accross so compromise is a must.
Hey everyone who help me on this tread. I forget to thank you! Because of sir Alex and his awesome thread, 2 hours on it! I'm searching for my jaw again! What a good thread.
I have right now 4.5 inches between tracks. But even on my little 11x11 layout I can have 5.5 or 6 inches.
So before make my tunnel, fix my bridge and going farther, I'm gonna adjust the interior loop.
Thankx again railgods!
Prototypically as example the Pennsylvania Railroad spaced main line tracks on a 13-foot center line for straight sections. On our 1:48 this is 3-1/4-inches. And this would work just fine with any of our 1:48 stuff as long as we went straight for infinite.
But our problems arise because our curves are no ware close as broad as prototypical. I have check all my large scale engines and rolling stock for "overhang" and "inhang." The worst case found was the MTH scale Big Boy with a front end overhang of 3 1/16-inches(from center line) and the cab overhang of something less on GarGraves O72 curves.
Also to note that Ross double crossover spacing is about 4-9/16-inch. This will work if using 089 curves or larger transition off of the straight section.
Hi all,
I did a presentation on this issue at one of the ORG Layout Design Roundtables at York. I've attached the Power Point from that presentation to this post. The presentation includes a graphic that demonstrates how the extremes of overhang and encroachment are measured. There's also a list of the measurements for the most extreme locomotives and rolling stock for each radius.
In my experience the most extreme overhangs are on the MTH DM&IR Yellowstone (more than the Big Boy), the MTH W-1 electric, and the MTH UP Coal Turbine (used the W-1's chassis but with body changes). For encroachment the limit setter on O-72 is the Atlas 89 ft. flat car. Not many people have that car, so I also listed encroachment measurements for several more common passenger cars.
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