Spline Roadbed 1: Oakridge to Helix Spline Construction

The final section of subroadbed to be installed on the lower level stretches from the south end of Oakridge to the entrance to the helix. The trackage is primarily on a sweeping curve and will feature transitional scenery from the flatter valley hills modeled in Oakridge to the steeper mountain terrain that will be predominant on the mid and upper levels. For this reason, spline roadbed is the perfect choice.

I have used spline roadbed in the past on the mid and upper levels of the railroad. For me, it is ideal for mountain railroading as it creates beautifully flowing curves, natural easements, and is narrow for steep scenery. As always, I start with reference to the track plan to lay out the curve, however, I am not married to it and often will use the spline itself to find the best fitting curve for the railroad in space. In this instance, the path suggested for the turnaround curve was rather awkward and tight so I elected to broaden it slightly.

Initial curve laid out with two masonite splines. Oakridge is out of the picture to the bottom right and the helix is in the bottom left. Also in this scene will be Salmon Creek and Pope and Talbot Lumber, which will fit against the backdrop. The view from a ladder is best to see the entirety of the curve at one time and make sure there are no awkward kinks or bends. 

After I have decided on the proper arrangement, I glue 2 or 3 splines together with wood glue. I have used 1/4" masonite ripped into 1" strips throughout the project. In this case I glued 3 layers together as the curve was manageable and easily accessible. 

Three layers of spline laminated together and drying with clamps. A good supply of spring clamps is necessary. 

When using two different types of subroadbed transitions are are necessity. For spline to plywood, it is best to cut a small key-slot for one of the layers to fit into. This ensures proper alignment and flow. Once all seven layers of spline are laminated, I will take more care into creating a smooth transition. 

Key slot cut and spline fit for transition between two subroadbed types.

Clamps holding together the final layers for the Oakridge to helix curve.

Completed spline roadbed with 7 layers of 1/4" masonite.

In the next installment I will discuss how I install the risers and fasten the spline to the benchwork. This area presents unique challenges given the height of the benchwork and future location of Salmon Creek.