It determines how much weight the bridge will hold. Bridges are very important to society because they help us cross large rivers, streams, canyons, freeways, railroad tracks, and more. A bridge is a structure used by vehicles and people to cross obstacles. Bridges are often used on highways all over the world. Without bridges transportation would be much more difficult.
Society is very dependent on transporting goods and people.
Everyone is affected by bridges. The first bridge that historians know about is an arch bridge built in Babylon around 2200B.C. Ancient Greeks, Chinese, Egyptians, and Romans built arch bridges too, mostly out of brick and stone. In the 1500 s truss bridges were invented. In the 1700 s cast iron and wrought iron were introduced into bridge building. In the late 1800 s steel was the most commonly used material in bridge building.