Making a curved tunnel

by Christian Andrews

One of the construction challenges I quickly encountered on the Mojave Desert and Southwest Mountains Railroad was a curved tunnel. The north end of the layout sports a double track curve overwhich I have planned a "mountain." All the articles I could find on building tunnels had straight tunnels, so I set about keeping my eyes open for contruction materials I could use for a curved tunnel.

What I eventually found were these cove and bead landscape boarder blocks

I set the blocks on a leveled bed of block wall 9"x12" caps. Even with the bottom of the first layer of edging blocks set below track level, three blocks high is more than enough tunnel hight.

After I had the tunnel walls in place, I removed the track and put in a layer of decomposed granite road bed. I sprayed for weeds first. (Weed control is a constant even in the high desert, but that is a topic for another time and another page.)

I covered the tunnel with redwood fence boards angle cut to fit. Each board has a cleat screwed to the underside hanging over the back side of the tunnel to help keep the boards in place. You will notice that I swapped in some brown edging blocks on the front side of the tunnel. These brown blocks are slightly smaller and slightly cheaper. I still have plenty of tunnel height.

I covered the whole tunnel in plastic to help keep the boards and tunnel dry.

The guy at the landscaping suppy called the rock I used for the waterfall "pot rock."

The tunnel is finished with dirt, a stream, water fall, and cast concrete tunnel portals.

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