What is a Bascule Bridge?

About Bascule Bridge:

• It is a type of bridge that can be raised to provide clearance for waterway traffic and is also referred to as a lifting bridge or a drawbridge.
• It makes use of a counterweight to balance a span or leaf through its upward trajectory.
• The balance of the weight is sometimes adjusted according to the frequency of waterway traffic.
• The counterweight is usually heavier than the leaf itself, which makes lifting easier and reduces the energy needed to operate the bridge.
• The span can be single or double, and in rare cases it may even be triple or quadruple.
• A pulley system helps raise and lower the bridge.
  • Cables or chains connected to the counterweight run through pulleys and are attached to the leaf.
  • This mechanical system helps reduce the force needed to lift the leaf, using something called "mechanical advantage.”
• The word ‘bascule’ is French in origin and translates loosely as a seesaw or a balancing mechanical device.
• It is thought that bascule bridges were first designed during the mediaeval era in Europe, when they served defensive purposes.
• The longest double-leaf bascule bridge in the world is the Broadway Bridge in Portland, Oregon, USA.