I’m building spline roadbed right now. A siding with two tracks.
How much distance should I use between the tracks?
The siding is mostly straight track but at the end it’s a curve. How do I know the distance between the tracks at the curve?
Track center to track center is 55 mm on the straight track. Must the distance be larger at the curve? I don’t know how to calculate the distance.
Here is a chart to help you out:
http://www.nmra.org/standards/s-8.html
It looks like somewhere between 2.25 and 2.5 inches, depending on the equipment and the curve. So somewhere between 57 and 64 mm.
Thanks.
I looked at the link you gave me and it seems that I’m on the safe side if I use 64 mm. My radius is 31 inch.
I agree. The NMRA standards are the best I’ve found.
Do you guys use the same distance for straight and curved track?
If tracks are side by side through a curve, they have to be further apart than on a straight, especially in a smaller radius. The space between two 18" radius curves must be greater than that between two 30" radius curves because of the increased overhang and bogie throw. Wouldn’t want two trains moving in oppisite directions to clip one another. The closest mine come are 1 1/4" or 32mm (rail to rail). This gives barely suffifient clearance between two trains pulling 60 foot cars which are the largest I run.
It would probably be advisable to place your tracks a little further apart than the recommended distance for the simple reason of being able to get your fingers in between cars to uncouple or rerail them.
I widen out from 50mm on parallel tangent track to 60mm on (minimum 610mm radius) curves, by using a longer easement with a 10mm greater offset to the inner track.
Even in a larger scale (1:80, aka HOj) my equipment is smaller (especially shorter) than your US prototype HO. I think your choice of 55mm parallel tangent spacing is excellent, and 64mm curve spacing should be more than adequate.
Chuck (modeling Central Japan in September, 1964)
I used 60mm between nearly parallel tracks out on my main, and I could have cut it down to 50 without too many problems. I agree, though, that if you ever have a need to handle items in one train that is as close as 50mm to another on a parallel siding, you are likely to dislodge something on that other train. If you are using heavyweight cars, and I am sure you are EL, then stick with a full 70mm on curves. Those long cars will have their centres hung well inside curves less than about 40", and if a steamer’s cab is anywhere nearby, you may swipe the two together.
You may also want to consider what the prototype used. This will depend on the particular railroad and era you are emulating. For example on the Southern Pacific in the mid-twentieth century, the standard distance between centerlines of double track or mainline and siding was 14’. If you have signals between tracks, you need to increase the spacing at those points for clearance. For the S.P. it was 8.5’ clearance from centerline to the signal’s outer edge (for a single searchlight signal, this resulted in a 19’ distance from centerline to centerline.) If there was a platform between tracks, the standard was that the platform be 9.5’ narrower than the distance between the tracks. (If the platform was 10’ wide, the distance between tracks would be 19.5’.)
As mentioned in earlier, you should also consider the NMRA recommendations, particularly for tracks on curves so there is adequate clearance.
Mark