Civil Engineering Professional Engineer Practice Exam

Which type of movable bridge operates by raising sections to allow clearance?

1. Drawbridge

2. Pedestrian bridge

3. Suspension bridge

4. Arch bridge

The correct answer is: Drawbridge

A drawbridge is specifically designed to raise sections of its roadway, known as bascules or leaves, to provide clearance for vessels passing beneath it. This operational mechanism allows for the effective navigation of marine traffic, accommodating large ships that require a certain height to pass safely. The ability to lift or pivot sections of the bridge distinguishes drawbridges from other bridge types, enabling quick adjustments for both road and waterway usage. In contrast, pedestrian bridges are typically fixed structures designed for foot traffic and do not operate to allow for the passage of boats or ships. Suspension bridges use cables and are designed for static loads, while arch bridges rely on compression and their curved shape to support weight, neither of which includes the raising mechanism needed for waterway clearance. The specialized function of a drawbridge makes it uniquely suited to situations where clearance is necessary, highlighting its importance in civil and marine engineering contexts.