3. Movable bridges

3.1 Presentation

When the height of the navigation gauge is significant (port areas, wide-gauge canals), the solution of crossing it by a fixed structure entails the construction of major access structures, which are sometimes unfeasible for lack of space.

Provided that the width of the gauge is only a few dozen meters, and that the road or rail traffic carried by the deck is not too restrictive, it is more economical to consider crossing with a movable bridge capable of giving way to shipping traffic, which has priority. The tracks can be crossed almost "level", with a minimum air gap under the deck, and without the need for access structures.