There are two Helix on the Puget Sound Model Railroad Engineer’s layout at the Tacoma History Museum in Tacoma, Washington. See the following website;
http://www.psmre.org/
They have done a great job with their Helix and have addressed the issue in two different ways which they explain in the photo history of the layout. Hope that helps.
Here is how i hid my helix. It is 2 turns, had to put this in to gain my elevation to the mine/sawmill/oil refinery level. There is access to it from underneath the layout.
I have 2 helix’s on my Atlantic Coast & Eastern layout, one exposed at the topmost level only (3 loops below to the bottom level hidden with 4 tracks of staging at the lowest level maintaining a 27 inch curve, with a 20 inch straight section after each curved turn which relieves the strain on the train as it rounds the curves). The exposed (top)level was scenicked as a river course running along the inside of the helix track and scenicked with a forested hillside on the inside of the river and the outside of the track portion as it loops down to a tunnel portal for the train to disapear into the hidden portion of the “loop tracks” and the river disapears behind a tree line.
The other helix is a bit more difficult to explain as I really exposed the whole helix as I broke it into scenic elements, well sort of. I’ll explain, this helix needs more than 120 feet of track to seperate the upper and lower levels of the railroad to about 16 inches from the top of the lower to the top of the upper level. It was designed so that it ducks in and out of scenic elements as it rises. Example, for the rise for the 1st turn of the helix it enters a tunnel (while in the tunnel it rises at a 2.5 grade for approx. 8 feet ( the longest section of hidden trackage) while maintaining a 24 inch radius, as it exits the tunnel I lessen the grade to about a 1% grade not quite level and scenically treat the next 6 feet (mostly straight) of track as two very large factory buildings with sidings and 6 stories high facing the operator. (The operator is now standing in the middle of this fully scenicked helix as the train runs around him) and disguises another level of loops which are behind these buildings, the track enters into one of the buildings and begins another 2.5 % climb (level 2), again out of sight for a full 24 in curve. Another scenic section (level 3) sits above and upon which the helix track runs exposed as a cinder fill. As level 2 exits a tunnel portal it runs along in front of the 3 foot trestle on level 4 and ha
Well done, Midnight; but, the original thread was re how to hide them in the Midwest (where there are no gigantic mountains to stuff them in).