movable bridge
Technical term for a bridge that can be moved to allow water traffic to pass, such as a drawbridge, bascule bridge, or swing bridge.
可動橋は、船が通るときに開く仕組みになっている。
A movable bridge is designed to open when ships pass through.
Compound of 可動 (movable) and 橋 (bridge). The exact historical derivation is uncertain, but the term is a straightforward modern technical compound.