Bascule

The most common type of movable bridge used for highway bridges is the bascule bridge. This type of bridge provides unlimited vertical clearance for marine traffic.  There are three types of bascule bridges: trunnion, rolling lift and heel trunnion. The most popular type is the trunnion bascule. Trunnion bridges can be single-leaf with one movable span, or double-leaf with two opposing movable spans. Double-leaf trunnion bridges are commonly found in areas with a wider navigational channel.