Bill Robb:
Yes, a very interesting and informative thread, thanks for posting. I’ve been using Superstreets for many years now but wasn’t aware of that parallel track gap created when using a Superstreets 90-degree crossover as shown in your first photo, or the track misalignment when using the new E-Z track switches to create a 90-degree intersection as shown in your last photo. I had bought a 4-pack of 90-degree Superstreets intersections a few years ago for potential use on my then planned layout but my final track design just couldn’t fit any crossovers. Have you tried putting a straight section in between the curved branches of the two switches? I know it would make the footprint of the intersection much larger but perhaps by using one or two 2½” curve-to-curve pieces would enable you to use stock pieces at the ends of the straight branches. My E-Z track switches are screwed down and in operation so I can’t try it with mine.
I have used D-16 curves nested inside D-21 curves on my Christmas layout every year but I only run one PCC on that layout so overhang is not an issue. But on my year-round layout, on which I run multiple PCC’s using insulated rails, relays and control blocks, I have left a “median” of about ½” to allow for the overhang as Lee Willis suggested a long time ago. Actually I don’t use any D-16 curves on this layout so I don’t have any nested curves just overhang locations on each end where one track of the double track line curves away from the other to start a loop.
Re non-concentric curves, those are prototypically correct as that’s the way Pittsburgh Railways did it on curves. I know I have some photos somewhere which show track around curves. All of the hills and intersections with diverging multiple routes required them to engineer unique track configurations including many S-curves.
Bill
