Which movable bridge has main girders that can be lifted together with the deck about a hinge located at the end of the span, and is also referred to as a drawbridge?

• A. Bascule Bridges
• B. Swing Bridges
• C. Lift Bridges
• D. Drawbridges

Answer: (A)

Movable bridges that open by lifting the deck along a hinge at the end are bascule bridges. The defining feature is that the leaves (the movable sections) hinge at the end of the span and lift together with the deck, typically balanced by counterweights to use less power. This is why the bridge is also commonly called a drawbridge—the visible action of the deck rising like a drawbridge is a familiar image.

The other types don't fit this description as neatly. A swing bridge rotates about a central pivot rather than lifting up about an end hinge, and a lift bridge moves the deck vertically but not in the end-hinged, deck-and-girders-as-a-unit manner described. So the mechanism that matches “lift together with the deck about an end hinge” and is also known as a drawbridge is bascule.