I’m going to be using Code 83 flextrack for the mainline and generally heavyweight applications, but elsewhere–sidings and low-speed places like yards–I’ll switch to Code 70. Am I right in assuming that the turnouts from the one to the other should be Code 83? Ideally, I suppose, the straight rails in the switch would be 83 and the curved rails 70, but that seems awfully complicated (does the prototype do it?). The point is: do I begin using the lighter rail after the turnout? Is there reason to consider an alternative?
Use the heavier rail for the turnout and make the transition after the turnout. I really doubt the prototype would make the transition in the turnout. Besides being complicated, it could cause maintenance and operational problems. I don’t see any benefit in doing it on the model or the prototype. Remember the “KISS” principle.
On the prototype they pick any place after the turnout to transition, some goe quite a distance before the change.
When I built my present layout, I did the same thing you are wanting to do. Go from code 83 mainline to code 70 in the yard. Because there is only a slight difference in size, you can’t really see it. The biggest impact visually is going from a mainline roadbed to no roadbed at all in the yard, and painting the rails. If I was going to do it again, I wouldn’t change rail codes. Too costly for the result. The only way that it looks good is when going from code 100 to code 70.
First item. Specialwork is always built with a single size of rail, usually the same as the heaviest adjacent rail, sometimes even heavier (to minimize maintenance issues.)
Then, rail sizes:
- Code 83 is in the ballpark for 129-135# rail, good for modern (and older heavy-duty) main tracks, down to and including the ‘main stem’ down the middle of a recently-built (post-2000) industrial area.
- Code 70 approximates 100# rail, which was mainline track on light-duty lines (the kind which would have been issued USRA ‘light’ locos.) It’s valid for yards and sidings which get heavy use.
- Code 55 (if your flanges can clear the fastenings) is good for older, little-used sidings. If used, there should be a length or two* of Code 70 before you get to the Code 83.
- Code 40 is too small for anything except mine tramways - and guardrails on my JNR prototype deck girder bridges (!)
Any siding still laid with Code 55 should have old, distressed ties and heavy rust. OTOH, a well-maintained yard will have good ties and be well leveled, with ballast to the tie tops and finer material up to the same level between the tracks.
- Prototype length, 25-33 scale feet, not 36 inch/1 meter.
Chuck (Modeling Central Japan in September, 1964 - with appropriate rail weights)