When originally built, the layout had no helix:
This worked well enough with dual locomotives pulling six to nine passenger cars up the hill, but once I bought my first subway car set I found that the hill was far too steep. I simply cut off the lower end of the ramp, built an open circle out of Celotex, and made this first helix The geometry remained the same:
But as the focus of my railroad shifted into a 100% subway layout, I wanted to rebuild the lower level including the helix to make it a four track main line:
I am using OSB board for the helix since that is what we have in our storeroom that I could take without having to spend any money. The former NYP level (lower in these photos) and the Prospect Park level (the upper level on the ping pong table) are with a Celotex deck directly on the open frame. I knew that the ping-pong table upon which this helix would sit is five feet across, and so the helix has a five foot outer diameter. The four tracks are laid inside of this as is seen in the photo above, but no real attempt to create a particular radius was used.
The lower level in this photo is actually a 5" tall table setting on top of the ping pong table. Thus the first riser under the helix is 5" tall. Each riser is made from a 2 x 6 board, each one 1/4 inch taller than the previous one. Thus the grade of this first turn of the helix is controlled by how far apart these risers are. On top of each riser is a builder’s shim which provides a 1/4 inch super elevation to the helix deck. For the next level the risers will sit on the level below and will all be of a uniform height of 2.5’. The helix will have one and a half turns to it and will end up 10" above the surface of the ping pong table, where
