Mr. Marc

"The beam bridge is the oldest, simplest, and most common type of bridge. A beam bridge is a horizontal, or level, structure. It has a support on each end. Other supports, called piers, may also hold up the bridge between the two ends."

"Like the beam bridge, the truss bridge has a support at each end. It may also rest on piers in between. But its structure gives it more strength than a simple beam bridge. A framework of metal or wood bars connects the two ends of the bridge. These bars fit together in triangular shapes."

"...the arch bridge is a very old design. An arched structure built beneath the bridge’s roadway provides its support. Arch bridges often span rivers and valleys."

"In the suspension type of bridge, the roadway hangs from strong wires called cables. The main cables hang between two or more towers. Smaller cables hang down from the curving main cables. The smaller cables hold up the roadway. Suspension bridges can span longer distances than any other type of modern bridge."

"A cantilever is a beam that has a pier at only one end, like a diving board. A framework of many bars adds strength to the beam, as in a truss bridge. At least two of these beams stretch toward each other to form a cantilever bridge."

"A cable-stayed bridge also uses cables to support the roadway. Its cables run directly between the towers and the roadway. They attach to the roadway in straight, diagonal lines."