I have an oval at one end of my 4X8 HO layout. It has Atlas 22" radius (44" diameter) track. I want to put a runaround track inside it using Atlas 18" radius track. Will there be enough clearance for 50’ cars to pass? Also How will the inside (runaround) track line up with #4 turnouts?
On curves with 18" and 22" radii, I recommend a minimum separation between tracks of at least 2.5", if you are going to operate longer cars and locomotives. Best suggestion is to mock it up full size with your sectional track, and check with several of your longest cars coupled together on both tracks. Move the curves closer together until you are just short of side-swiping. Then you have the minimum clearance for your equipment on that radius of track.
Look at Atlas’s book HO Layouts for Every Space (see http://www.atlasrr.com/books.htm). Earlier versions had templates of how to nest curves inside each other with adequate clearance. I assume present versions of the book still have them. Some of the Atlas track plans in this or their other books will also show aligning curves using Atlas #4 turnouts - which generally work well with 18" and 22" radius curves.
Another way to try out your ideas is to download and use Atlas’s free RTS track planning software.
Hope this helps.
Fred W
It will work providing you do your part. This is a perfect application for Right Track, and I say that very infrequently. You may have to add a short piece of flex or cut one of your sectionals. If you go with flex from one turnout to the other, you might do better than 18" though.
I downloaded RTS V 7.0 yeaterday and couldn’t follow the directions for a figure eight!
I was not aware that it might do more. I will try again. Thanks
B.B:
Popular spacing seems to be 2 1/4 " for #6 crossoners. That’s what both my Shinohara and Tru-Scale prefab came as.
A pair of #4’s or #5’s will automatically be wider when placed back to back, and shouldn’t be as much a clearance problem as - when tracking the ‘S’ curve .
In general, 8 wheeled diesels do better on #4’s than 12 wheeled ones. I have laid one of crossover of each for run-arounds, but haven’t tested the Walthers #5’s yet.