I recently saw a video made by BUDD RDC here http://www.youtube.com/watch?v=AGP8EI8aY9g&feature=related . and it showed a train ( RDC ?) going over a short plate sided bridge (looked like 50 feet or less ) on a straight section and It had guard rail from beginning to end over the bridge like it was a switch , but wasn't. Video was made early 50's but I am sure the bridge had been there quite a while. Why would the put guard rail on a plate bridge on a straight away ? Should we model that perspective on all bridges reguardless of type ? I went and got my plate bridges (Atlas) and they do not have guard rails like swithches do. Or , is it a special bridge that they do not want us to know about ? One to confuse and confound the enemy ? Ha! Inquiring minds want to know
You are correct that those inner rails on bridges were guard rails. However, their purpose was to prevent a derailed axle or truck from leaving the track and dropping off the bridge. They were more important for long freight trains where a car in the middle might have a derailed truck that could not be seen from the engine or caboose.
