Joining the railroad along Salt Creek is the Willamette Pass Highway, Oregon Hwy 58. Salt Creek Trestle spans both the creek and Hwy 58, providing easy access for viewing railroad action on that trestle. The highway is an important part of the scene.
One challenge faced by my model scene is that I compressed out of the scene many miles of creek and highway. While I planned for the highway to pass under the trestle, I needed to have it disappear from the scene. The prototype Hwy 58 passes through a tunnel further up the pass. Having my model highway plunge into a tunnel would be a good way to disguise its exit from the overall scene.
I laid out my Hwy 58 on a broad curve that sweeps under the trestle and then curves off to disappear into the tunnel under the roadbed for Wicopee. Viewing from the edge of the layout, this makes for a sweeping left curve. I laid out the curve on cardboard and cut that to represent the highway--about 25 HO-scale feet wide. This was then transferred to hardboard and cut out as the initial form of the highway.
Highway 58 route laid out. The Salt Creek Trestle towers were removed for scenery work around the piers seen in the upper portion of the photo.
As I worked with the highway scene, I needed to have it rise a bit from Salt Creek Trestle, just as the prototype highway climbs toward the pass. I formed the initial road grade using the insulating foam used for terrain formation. Some of this needed to be sliced to thinner profile and then smoothed to make a good road grade base. I then added a subroadbed of hardboard that I could sculpt into the terrain using Sculptamold. The "final" highway (hardboard) could lay on top of this allowing removal for further highway pavement treatment.
Rough highway grade.
Slicing the insulating foam to the desired thickness. A belt sander was used to further smooth and shape this road grade.
Once the highway was prepared, I built the tunnel. I used blocks of three-inch thick insulating foam to form the tunnel. Laying out the tunnel arch with a pen, I cut out the desired shape using a bandsaw. I created a cut stone face to the tunnel portal by drawing it onto the foam with a pencil. The pencil embossed the foam. I painted the tunnel interior gray and then added a thin mixture of Sculptamold to the portal. I needed to go over my "stone" embossing so it would show through this thin covering.
Highway 58 tunnel segments joined. The portal has been embossed using a pencil to form the cut stones used on the prototype Highway 58 tunnel.
Highway 58 tunnel fit into the terrain. Spray insulating foam was used to fill cracks and form rock outcroppings around this area. Most of the white spray foam seen here was trimmed back before the Sculptamold was applied. The hardboard highway subroadbed can be seen in the foreground.
Highway 58 tunnel installed within the terrain.
With Highway 58 installed, I can move on to other parts of the Salt Creek scene.