I used Mianne benchwork with 1/2" plywood on top. Mianne supplies 90 degree clamps to hold the plywood to their framework, but I feel that tripling the number of clamps would help with some noise reduction.
I used 3/8" thick anti-fatigue matting between the plywood and the track for roadbed, stapled to the plywood. I secured the track in place by using small zip-ties, trying not to get them too tight. I got the matting at Lowes, they used to have it on a roll you could get cut to however many feet you wanted, but last time they only have pre-cut 5 foot lengths. When I first started using this matting, I calculated it was cheaper than buying the cork roadbed, not sure if that still holds true.
I then sprayed some Rust-Oleum Stone textured paint onto the edges of the matting (should have done the whole thing BEFORE I put down track). I have found once you put ballast on the noise is there to stay, this "spray on ballast" I thought would be a fair alternative.
Once some ground foam was added I thought it looked presentable and after a while I don't even notice there's no ballast between the ties. Spraying the entire matting before laying down track would have helped that illusion.
I still have noise but if I would add some more 90 degree clamps underneath the plywood I think it would help. All my engines are battery powered without sounds, I can hear the train "noise" over the generated, vibration noise as they go around the layout so that tells me the noise level is acceptable. I've added cloth skirting around the edges of the layout, but that hasn't seemed to lower the noise level.
I'm also positive the unwanted noise is coming from underneath the layout, being I don't have any wiring I may try some noise reducing batting/insulation to see if that helps.
