@Ted S posted:Very nice! I know that I've seen other write-ups that place the helix on a peninsula. It might have been in this DVD, which I heartily recommend, BTW.
Personally the idea of having switches on the helix makes me uncomfortable. I guess I would omit the third loop around the peninsula in the interest of reliability. Also, I would try to lengthen the run-up to keep the grade below 3% in both directions.
Of course doing this with wide radius (O72 or greater) takes a large room. But the general configuration and benchwork make excellent use of the space. More rectangular plans should probably be designed with a peninsula extending from the short wall.
Ted, you may be right, there will be a lot of drag force pulling a train up the helix, which will threaten to string-line the cars across the O72 turnout in the middle of the helix. Unfortunately, there is nothing in Atlas-O between and O72 and #5 turnout. I could look for a Ross that might fit.
I suppose the prudent thing to do would be to delete the middle level, turnout on the helix, and reduce the upper route to 8", reducing the grade up the helix. That would make for a more reliable layout. But... then the middle level shelf would only be 8" above the layout base, making it hard to see and appreciate the layout under the middle shelf. Tradeoff. Maybe 10" would be about 3%.
