Moveable Bridges

Even though they aren't that commonly used, moveable bridges are so interesting! We loved learning about them. Bascule Bridges (drawbridges), Vertical-Lift Bridges, Swing Bridges, and Transporter Bridges are the types of moveable bridges we talked about.

This is a swing bridge. The entire center span can rotate 90 degrees to allow boat traffic through, and then rotate again to complete the roadway. We made this easily with a cardboard span attached to a goat-cheese container lid with a brad. We filled the pan with water so our boat could float through.

Transporter bridges, our book said, are hardly ever used anymore. They move across two suspended cables almost like a horizontal elevator. The entire span or platform moves to transport cars across a small river or gully.

Partially lifted

This is a model of a vertical-lift bridge. When the bridge is down (I don't have a picture of this), cars can go across the span, which stretches between two pillars (the Wheaties boxes) like a regular bridge. When boat traffic needs to pass, the entire span lifts up vertically through a system of pulleys. Then boats can pass underneath with no obstructions in the water (bottom picture).

Our favorite double-leaf bascule bridge is Tower Bridge in London, and we watched a video of it lifting. This site also has an animation of both single- and double-leaf bascule bridges at work.