Check out these detail parts

[chuck geiger]

http://www.ashlintrains.com/servlet/StoreFront

[asciibaron]

i like the helix kit - 2% grade on 6.5 turns to gain 15" - for $100.00.  that seems reasonable.

-steve

[ednadolski]

The HO kit would probably work well for N scale -- more clearance and larger radii.  I'd bet you could stack multiple kits too.

[cv_acr]

Ah, a nice, simple helix. Haven't seen one of those in a while.

My train club has several of them, and we all know that helices and turnback loops take up a lot of room, so...
we stack as many in one spot as we can to share space.

http://www.wrmrc.ca/construction17.html
http://www.wrmrc.ca/layout10.html
http://www.wrmrc.ca/layout16.html

This one's actually nice and simple, it's just two single track helices stacked on top of each other.
http://www.wrmrc.ca/layout12.html

[Mark5]

Them buses have doors on the wrong side!  

Hmm, the helix looks like 1/4" plywood. Bet it would be a noisy thing. Still it is interesting.  Curves too sharp on most of them for my taste.

[up1950s]

Nice helix's for a logging or turn of the century before the last one , but I agree it would be too sharp for a long train . The 48 incher's for HO would be better for N , and with the extra width , threaded rods through the plywood  would be better for supports as they are adjustable and block less track .