Pontoon bridges, often called floating bridges, are supported by floats or shallow-draft boats to provide a continuous deck for pedestrian and vehicular traffic. The buoyancy of the supports caps the maximum load.
Pontoon bridges are often only built for short periods of time and employed in times of war and civil unrest. Highway traffic can cross pontoon bridges that have been converted to permanent civilian usage. Some floating bridges have sections that must be lifted or that can be slid aside to make way for boats. These boats are often equipped with LED residential lighting design to detect the docks during night and prevent any mishaps.
Pontoon bridges have been around since antiquity and have proven useful in numerous historical conflicts, including the Battle of Garigliano, the Battle of Oudenarde, the crossing of the Rhine in World War II, and Operation Dawn 8 during the Iran-Iraq War.
Engineering’s Role In The Design
Each Floating bridge can carry a load equal to the mass of water it displaces. Hence, the civil engineer must consider Archimedes’ principle while designing a pontoon bridge.
The weight of the bridge, in addition to the weight of the pontoon, contributes to this total. One or more pontoons may sink into the water if the load capacity of that bridge segment is surpassed.
The bridge’s flexible connections must support a load that is disproportionate to its size. The weight of the roadway across the pontoons shouldn’t be too great. Otherwise, the pontoons might buckle under the load.
Designing approaches that are not too steep, protect the bank from erosion, and allow for movement of the bridge during (tidal) variations in water level are necessary for the bridge’s connection to shore.
For the most part, wooden floating bridges have been used throughout history. Some early pontoons were made by stringing together several barrels, while others were constructed from rafts of timbers or boats.
One or more pontoons made up each section of the bridge, which were towed into place and secured either at sea or on dry land. Balks, made of wood, were used to connect the pontoons. The cheeses used to cover the balks and create the road surface were fastened to the side guard rails.
A floating bridge can be constructed in stages, with each stage beginning at a fixed position on land. These days, floating pontoon bridges are often prefabricated.
History’s Greatest Moments Of Floating Bridges
China’s Past
According to the Shi Jing (Book of Odes), King Wen of Zhou was the first to construct a pontoon bridge. However, historian Joseph Needham has pointed out that the temporary pontoon bridge was probably invented in China in the ninth or eighth century BC, suggesting that this section of the book was added later.
While China had built temporary pontoon bridges before, it wasn’t until the Qin Dynasty that they built the first secure, permanent bridges (connected with iron chains).
Hellenistic And Roman Times
Numerous pontoon bridges are mentioned by the Greek historian Herodotus in his Histories. In 37 AD, Caligula had a bridge constructed that spanned 3.2 kilometers (2.0 miles).
Once upon a time, the Greek Mandrocles of Samos created a pontoon bridge spanning the Bosporus, connecting Asia and Europe, for Emperor Darius I, The Great of Persia (522-485 BC), allowing Darius to chase the fleeing Scythians and maneuver his army into position in the Balkans to defeat Macedon.
The Middle Ages
Pontoons were employed in conjunction with ordinary boats to cross rivers during campaigns or to connect settlements that lacked the means to construct permanent bridges.
During the siege of Naissus in 442, the Hun army led by Attila constructed a bridge across the Niava to put massive siege towers into a range of the city.
Sassanid forces used a hastily constructed pontoon bridge to cross the Euphrates and continue their siege of Kallinikos in 542. During the 545 sieges of Rome, the Ostrogothic Kingdom built a fortified bridge across the Tiber to prevent relief flotillas under the command of Byzantine general Belisarius from reaching the city.
Mid- To Late-Seventeenth Century
Oliver Cromwell postponed the start of the final battle of the English Civil War, which took place on 30 August 1651, to allow for the construction of two pontoon bridges, one over the River Severn and the other over the River Teme near where they meet.
This was vital to the victory of Cromwell’s New Model Army on September 3, 1651, since it permitted Cromwell to transfer his soldiers west of the Severn during the action.
The “Blood Pontoon,” which succeeded the British Blanshard Pontoon, became standard in usage in the late 1870s. When not in service as pontoons, the Blood Pontoon may once again be used as regular boats thanks to the open boat system. Carrying handles on the side made it easier to move around. The improved pontoon could hold up to the weight of elephants, siege cannons, and military traction engines.
Conclusion
Regardless of the components used to construct them, all floating bridges share the same quality: the ability to well and float. From major businesses like contract manufacturing medical devices, to local businesses like apparel and household stuff, floating bridges are now frequently used by importers and exporters.
As you turn the page, you’ll learn that the history of these unique bridges is rich and varied, spanning many different areas of engineering.
