Historic photo of the Miami & Erie Canal's Mad River aqueduct on March 23, 1911. This aqueduct was destroyed in the 1913 flood and it was never rebuilt. Only the southern abutment remains. Even here it's already derelict. The posts atop the towpath bridge held railings that only remain at the far left side of the photo. The structure is called a three hinged arch, despite the top chords of the arch being straight members. The angled members brace each other and rest against angled bearing blocks (thrust blocks) in the stone piers. A floor beam is hung with iron rods from the center of the arches, and the canal trough spans through everything. It's not actually a truss although it sort of looks like one. Thanks to Jim Graham for the structural information. This is the same aqueduct design that was used at the Cincinnati & Whitewater Canal's crossings over Dry Fork Creek and the Great Miami River in Cleves.