The height of the trusses really does'nt matter. I've seen very short ponies, and some that are quite tall. The overhead struts, top lateral bracing, and the sway bracing(on larger bridges) is what constitutes a thru truss. Any truss bridge without at least the overhead struts would be considered a pony truss. This of course is with the trusses above the roadway......if they are below, it is a deck truss.
Is there a certain heighth requirment for the truss to be considered a pony truss as opposed to a through truss? I have seen bridges that are listed as a pony that is quite a bit shorter in heighth than the one pictured here. I understand that the through truss is held together at the top by cross angles and such, but the fact that this bridge posted here is completely opened and is taller than most ponies I have seen. Can someone help me differeniate the heighths and what constitutes a pony truss? Is there a possibility that the pony truss is a certain design rather than the shorter version of the through truss? Harold