We see bridges everywhere. Whether bg or small, bridges make our lives easier. A modern bridge usually has a framework of concrete, steel, or wood. The roadways, the part we walk or ride across, are generally made of asphalt or concrete.A bridge must be able to with stand all the forces of nature - hurricanes, blizzards, or earthquakes. The best bridges are beautiful as well as useful. Early beam bridges helped people cross rivers and cayons. Some beam bridges were made of several logs tied together and covered with branches. Beam bridges are simple in desighn and cost the least. The most common bridges in the US today are beam bridges.
An arch bridge is shaped like a curve or arch. Roadway on an arch bridge usually lies either above or below the arch.
Modern suspension bridge, most of the bridges weight is distributed through the cables to the anchored points. ( )

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