Bridges are marvels of engineering that stand inconspicuously amongst us. We don’t think of them much even when we are passing over them. Nowhere are these structures more impressive then when they are constructed over water, which brings us to the question of how are bridges built over water.
Welcome to Engineering Discoveries. In this article, we will tell the answer…
Bridges are built over water by different methods (depending on the level of water and quality of the soil).
The first method is utilized for bridges that are constructed in shallow water. The foundation of the bridge is placed in low-depth water by permanently filling the specific spot, over which piers are built (a type of pillar can be built). However, when the soil at the top layer is unsuitable for building a bridge, temporary rigs are erected and piles are built deep within the river bed. The bridge can then be built using either the already completed piers, temporary platforms/mud islands in the water, or barges (though rarely in fewer depth glasses of water).
The next method is for the bridge constructed over deep water bodies (rivers or seas). The cofferdam technique is used in this case. In this method, a wall enclosing an area is built inside the water, and water is continuously pumped out from the area. After that, the foundation of the bridge(the pillars) is constructed inside the cofferdam. As the construction place is sea or river itself. Therefore, 24-hour watching is required outside the cofferdam to check high tides of water. Bridges build using this technique are strong and carry heavy loads.
And the last technique is called Case Drilling. This is the most advanced technique. In this technique, a water-tight chamber keeps the water away with the help of air pressure. Then a sealed tube chamber is fitted inside the chamber. After that, a long drill is put inside the tube and then the drilling process starts. Water filled during this process is pumped out. After that, a case is inserted into the hole which is drilled inside to give extra support. In this way, a stable frame is created. This frame is filled with concrete. Then pillars are built and hence the bridge.
29+ Images Illustrate How Bridges Are Constructed Over Water