Emailed to Nicholas, is this helix what you're looking for?  The outside track is 10' diam. and the inside track (as sidings) is 9' diameter.  See my Four Level Track with Helix Access for how to information.

My MTH Big Boy pulls long freights (60 car) up the helix with ease.  If your building one that large I have the cut out drawings for the base parts.  I'm happy to share the drawings.


I took a look at your Helix page.  You mention sidings, but I am unclear how these work.   I would like to break out of the helix part way up with a track switching off, but for the helix to continue up.  I have heard to avoid putting a switch on an incline.  It becomes difficult to interrupt the helix to make a level spot for a switch.

How have you connected your sidings to the helix or do I misunderstand what a siding is?  Do sidings mean "approach ramps"?   Is it even possible to switch out of a helix?


As the helix track starts up the steady curved grade there is an inside and outside track.  Using Ross curved switches, trains can move between the two tracks and also tie into the stub tracks on the wall.  My inside helix tracks are sidings.

Switches work fine between the inside and outside track because the grade stays the same.  Switching off the outside track to stub tracks on the wall requires some very careful calculations and trials.  Some of the tracks between the helix and the wall track are long to allow the grade to level.  The switches stay helix grade and that long tie in track adjusts to the level wall track.

With software I was able to work out the grades.

Look at the helix at the far end of the room here  7. Run Room looking from North end to South end.  That gives you a feel for the access to the helix.

This drawing also helps:  Run Room Main Area Track Plan


Run Room looking from North end to South end


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