Part of my solution came in the form of acrylic-latex caulk (the type used around doors and windows). I use gray caulk full-strength to cement the track and roadbed in place. While the caulk is still wet, I apply the first layer of ballast. Once the caulk has set, I dress the ballast, apply water to wet it, and then bond it in place with clear acrylic-latex caulk, diluted 1:5 in water.
While using caulk as an adhesive greatly limited the transmission of sound, I’ve also started using a few other sound-dampening products for even better sound control. As shown in the illustration, my subroadbed layer starts with a strip of 15mm (roughly ½”) foam padding, the kind used for camping sleeping mats. I cement this to the plywood layout surface with the acrylic-latex caulk.
On top of the foam mat, I lay a 4mm-(5/32″) thick strip of automobile sound insulation. This is a dense asphalt-based product with a self-adhesive backing. I found it in an auto parts catalog, and it’s sold in sheets. I cut the material into strips to use on the layout, and it provides good support for the cork roadbed and track.
I’ve also managed to limit the amount of ballast I need (further cutting down sound transmission) by building up the right-of-way profile using half-strips of Woodland Scenics foam roadbed, as shown in the illustration. I cement it to the subroadbed with caulk.
Though the process may seem like a lot of work, it’s all worth it when I watch my trains glide along the main line with the only sounds coming from their on-board sound decoders.
