Which bridge uses pre-stressed steel or concrete and has no direct under supports?

• A. Beam / Girder Bridge
• B. Truss Bridge
• C. Rigid Frame Bridge
• D. Cantilever Bridge

Answer: (D)

A bridge built as a cantilever relies on arms that project from piers to support the structure, with the central span carried by those cantilevers rather than being supported continuously from below. Prestressed steel or concrete is well suited for this design because prestressing strengthens the cantilevered arms, allowing long spans to be constructed and resisted against bending without needing temporary supports along the midspan. The deck is typically joined between the cantilevers or hung from them, but at no point is there a direct support underneath the middle of the span. Other bridge types generally require supports under the span or at multiple points along it, so they don’t fit the description.