For HO highway guard rails I used N scale flex track ties, coragated stryine siding cut in a strip for the steel guard rail. Leave first post(tie) full lenth and aprox every fifth or so. Set ties in place on layout, using a dremil, drill the first hole and set post, the the next long one. glue guardrail to ties. Use a drill that ties can be forced in if in plywood, easy to remove. The road is not done yet but were getting there.
Bernard/Acela. I am not sure about the Z scale flex track. However if there is a strip along the ties that hold the spacing, (as like in the picture of N scale ties above) I think it would be OK. Anothrer thing I did not mention, I used the N scale rails for my bridge rails, being a smaller scale rail. I think the Z scale rails would work for you bridges and if the ties also work its a better bang for the buck. Here is another sot of the ties, please excuse the unfinished road and facia. May be a while befor I finnish it, installing 1 to 1 scale windows for my wife and other assorted items on her HUNNY DOO list LOL ...John.
