My layout is flat, but to break things up I wanted to add a couple bridges. I was planning on setting them right on top of my table top. I'm laying Atlas track on top of cork roadbed. I at first was thinking of getting the Atlas truss bridge as I really like the look of it, and the size would give it great presence. But them after looking at photos online, I see that there is quite a bit of structure under the track, which would be an issue. So I started looking at the MTH arch bridge and Lionel truss bridge (Not the new FasTrack one.), neither of which are as big as the Atlas one. I saw that MTH's arch bridge can be made "bigger" as it were by adding the girder bridges to either side to make it as long as you wanted, but it also seems to have some structure under the track, but not as much as Atlas. Lionel's is just a sheet metal bottom so I could put it right on the table top and lay the cork and track on it, but I don't know if I want cork on the bridge.
So, who has used them right on the table top? What did you have to do to do so? What did you learn you wish you knew before hand?
I'm leaning towards the MTH bridge, but I need to know how thick the under track structure is. Will the cork space the track right up to it, or will I need to get higher?