Maybe it’s just the mild climate here, but I’ve never had any problem with sagging roadbed when I’ve used a glued-together sandwich of Homosote and plywood over 16” spacing between risers. Even when I’ve used ½” plywood it always felt plenty stable, even overkill.

So for light weight and ease of handling, I decided to risk being scolded by wiser and more experienced modelers and used ¼” plywood on this layout. I admit that I’m nervous about having to eat crow, but so far I’m not seeing a problem.

Maybe people are just used to leaning on their roadbed when they need to reach in. This layout is mostly 16” deep so that won’t be necessary (or allowed).

But I’m bracing myself for a lesson learned “the hard way.”

I haven’t used cork roadbed since my very first layout, 50 years ago, so in a way I can’t say that I “prefer” Homosote. I’ve just never been tempted to use anything else. I like the idea of the pre-cut half profile kerfed strips, those make sense to me, but I feel like I’ve been a bit lazy not working out a jig to make them myself. I find that I enjoy the process of hand-carving the ballast shoulders, switch stand ballast prisms, between track- and trackside ditch details in the Homosote, so I’ve been content to stick with cookie cutter roadbed, cutting both layers at once.

I seriously considered Homosote splines for this layout and very nearly went that way, but the details of the 8-foot section joints just seemed more comfortable to me with horizontal layers.

The kids had lots of fun learning to guide a jigsaw and generated plenty of fluffy dust.

 Once the pieces were cut, students paired up to apply glue to mating surfaces. I didn’t have enough clamps for this many pieces at once, so we just laid them on the floor and piled books on the sandwiches.

Kids love glue.

Incidentally, the diagram on the whiteboard in the background was from my lesson on parabolic vertical curves, which are a key feature of the layout design. Discovering the many ways in which the elegant mathematics of the parabola figure in their daily lives creates a lot of excitement for kids, so I sort of bend the curriculum a bit to get them familiar with them sooner rather than later. 

Jeff Allen