I make my own out of a piece of U channel. Even in real life they are not very complicated, at least the ones on horizontal ground. If the bridge is using something like canyon walls to withstand compression, they can get complicated. But most simple ones use either roller bearings or even sliding plates.
That's a big bridge. How about O Scale shoes? http://www.sceneryexpress.com/prodinfo.asp?number=FL6039
Ooops, terminology misunderstanding. I thought you were looking for just the top part that connects the bridge to the mount, which is also called the shoe. Tony's showed you one solution. I just use bits of styrene, in a very simplified construction, for the entire mechanism. Those are big shoes! I'll have to go looking at shoes next time I'm around some big bridges.
Pete- Greg has a thread in the Milw Fallen Flag Forum. Have you seen it? The bridge he's building is going to be unreal when completed. Boxcab E50
Ken, Not at the moment. Working from west to east: I have the first set of seven deck trusses completed. Now I have to scale out the next three, which are suppose to be longer in length. After those next three are completed I'll have the thing built up to the through truss. My seven deck trusses measure 131 scale feet each, 25 feet less than the real deal. So from the naked eye these seven look pretty close to the real thing. My plan is to get all the trusses built first then go back and build the top girder plates. I'm also working on how I'm going to do the piers and obviously the shoes. Once I get some picture worthy stuff I'll post some pics. Thanks for the help guys! It looks like I might be mixing a few commercial items together and also doing some custom made stuff to get my shoes.
Thanks, Ken! I had missed that thread--it's just WOW! Very nicely done, Greg! I use much the same technique to cut bridge parts. I print the bridge full size for N scale, then use the print(s) to cut the correct angles. I assemble the sides of the bridge on the print. I guess I'm going to have to take longer hikes the next time I'm in Alaska, to look for the shoes. I was hiking toward the Nenana bridge (690' span) the last time when a black bear diverted my attention.
Fine N Scale also makes bridge shoes, they are sold with piers meant to support the Micro-Engineering tall steel viaduct. Not exactly what you're picture shows, but a lot closer than the Micro-Engineering castings.
I also found pictures of the shoes on the Tanana highway bridge. but they seem not to want to upload. Modest affairs.