Pontoon Bridge: What is it for?

Pontoon boats or pontoons are usually flat bottomed boats. Pontoon boats have floats to support a certain structure on the water. This can be as simple as a flat deck or as complicated as a house-like structure.

One of the most useful designs for pontoons is to make it into a bridge. A pontoon bridge is a bridge that floats on water. A pontoon bridge is supported by barge or boat like pontoons.

Generally, these kinds of bridges are temporary structures. However, there are some pontoon bridges that may be are utilized for long duration of time. Sometimes, permanent floating bridges are built on areas where building a suspension or a cable bridge would not be considered as economically feasible. Suspension, cable or anchored bridges would need a section of land with elevation.

The military makes use of pontoon bridges during wartime at river crossings. Usually, these bridges are temporary and are destroyed or collapsed after the battle group crossed the river. This is done to deny access to the opposite side, their enemies.

Early pontoon bridges were made of wood and were built in a series of sections, beginning from an anchored point on the shore. The pontoons were formed by using boats with a number of barrels tied together. Rafters or timbers are then fastened to the barrels, forming a bridge section. Several of these sections were then maneuvered and anchored, forming the length of the bridge.

The sections of the pontoon bridge were then joined together using wooden stringers called balks. Once this was done, the balks were covered by wooden planking to form the roadway. The process was then repeated until the bridge reaches the other shore.

Pontoon bridges of today are designed the same way although the use of new materials and improved engineering technology makes them lighter but stronger.

Designing a pontoon bridge is quite tricky. The engineer must consider the maximum amount of load that it is intended to support. The pontoon of each section of the bridge can support a load equal to the mass of the water that it displaces. Once the maximum load of the bridge section is exceeded, one or several pontoons may sink. Also, the roadway of the pontoon bridge must be able to support the load but light enough for the pontoons to carry.

Pontoon bridges are quite safe. However, accidents do happen. For example, strong winds, strong water currents and flooding can pose a danger. Overloading the bridge may also cause the anchors or connections between bridge segments fail and can also be dangerous.