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hminky@yahoo.com
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Draw up a plan
Narrow gauge technology is basically based in the late 1870's. Here is a standard gauge tunnel for that era. It was typical of the style found on most smaller narrow gauge railroads. We will be building a tunnel similar to the Standing Stone Tunnel on the Ohio, River and Western. It is shown in Edward H. Cass' book Hidden Treasures. We are adapting the plan from his book.
This is the original On30 tunnel. It was an S scale portal. I never felt it had a narrow gauge look.
 At right is the tunnel portal from the "ill-fated OO/HO in the 1870's" project. It was a modified Woodland Scenics plaster HO tunnel.

I cut the plaster tunnel out of the mountain. The plan from Cass' OR&W book was scanned. The tunnel was on an 18" radius curve so the portal had to be larger.
A cardboard "tunnel" was mocked up and held together with paper clips. This was used to determine the tunnel size and clearances.
The largest pieces of equipment were used to determine the size of the tunnel. Back the locomotives through that is when the most clearance is needed.
After determining the inner size of the tunnel a plan was developed using Pro/Engineer Wildfire 3d modeling software.
The plans are available as downloads in PDF format from the website. You will need Adobe Acrobat Reader 5.0 or higher.

Click here to download the whole tunnel drawing prints on ANSI C-paper for full size views
Click here to download the front view - Prints on 8-1/2x11 full size
Click here to download the side view - Prints on 8-1/2x11 full size
Click here to download the top view -  Prints on 8-1/2x11 full size
Click here to download the section A-A view - Prints on 8-1/2x11 full size
Scratchbuilding the Tunnel Portal
Click here to build this  narrow gauge tunnel portal
Planting the Tunnel Portal
Click here to place this  narrow gauge tunnel portal into the mountain
Print the single views with Page Scaling set to: None
The assembly on 8.5x11 use: Print to printer Margins.