The minimum radius on Tom Harris’s Lakeside Lines model railroad is 60 inches. Allen Keller wonders if that requires some special kind of roadbed or preparation as it is such a huge radius. Tom uses a special kind of roadbed to make that kind of curve float nicely. Tom demonstrates how he builds his spline roadbed. His framework consists of two by fours screwed to the joists that hold up his train room.
Next he clamps some spline onto this framework, which makes nice flowing curves. He puts the front end of these blocks where the back end of his roadbed is going to be. He roughly plots where he wants his roadbed to be and places the blocks down right where he wants them.
Tom built his spline roadbed out of something called Blackboard, which comes in four by eight sheets and sold in the installation sections store. It is very flexible and easy to use and it does a good job. He starts with the smaller size, which is two inches tall. He starts by putting up a strip of the smaller size on these blocks which will be the ditch for my road bid. He uses two sizes so that the smaller size will be lower for the ditches.
If the track is not properly ditched, then the scenery will never look right. This is because when the railroads build their lines they always put good ditches on the side to make sure the track stays nice and dry. Next he attaches the next part of the roadbed using glue to hold it in place. He applies wood glue on the side of the next piece of roadbed.
To see the spline roadbed completed watch the full video, and watch more from Allen Keller’s Great Model Railroads in the Model Railroad Academy archives.