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A pratt truss bridge design includes vertical components and diagonals that slope down towards the center. It was invented in 1844 by Thomas and Caleb Pratt. It was a common solution for railroad bridges when wood truss elements were replaced for metal. Here you can learn more about its history, its basic capabilities, and some of its most famous bridges that use it.
A trestle bridge is a bridge composed of a certain number of short spans which are supported by trestle frames. A trestle frame is a platform for supporting the weight and maintaining the stability of some object. This type of bridge is also called a trestle, because of a framework of frames which define the cross-section of a timber frame building or supports a trestle.
Beam bridge is the oldest and the simplest type of the bridge. It appeared when the first tree fell over the stream and a human crossed it. Today we still make bridges that use similar principle.
Modern cantilever bridge is one of the safest bridge variants because it can carry largest load. Since the dawn of the modern bridge, in 19th century, they were used to carry railroads.