Fishbelly Deck Truss

Fishbelly deck truss bridges are an exceedingly rare form of deck truss with a distinctive polygonal bottom chord that is parallel to the top chord on all panels except for the last couple panels, where it slopes upward to meet the endpost. The design was usually employed where a substructure was being reused to build a new bridge, but the new bridge needed deeper trusses so it would be stronger. making the truss deeper in the center, but shallower at the ends allowed the substructure to be reused, while also offering the strength of a deeper truss.