Editing Plate girder bridge (section)

==Semi-through plate girder bridge==
[[File:PlateGirderBridgeUType.jpg|thumb|left|upright|Plate girder bridge: half-through type.]]
In the half-through bridge (also called a '''pony truss'''), the bridge deck is supported between two plate girders, often on top of the bottom flange. The overall bridge then has a 'U'-shape in [[cross section (geometry)|cross-section]]. As cross-bracing cannot normally be added, vertical stiffeners on the girders are normally used to prevent buckling (technically described as 'U-frame behaviour'<ref>{{cite web |url=http://www.steelconstruction.info/Design_for_half-through_construction |title=Design for half-through construction |publisher=Steelconstruction.info |access-date=26 December 2014}}</ref>). This form of bridge is most often used on [[railroad]]s as the construction depth (distance between the underside of the vehicle, and the underside of the bridge) is much less. This allows obstacles to be cleared with less change in height.