THE BRIDGE The bridge is a structure built to span a valley, road, river, or any other physical obstacle. There are three major types of bridges: The beam bridge The arch bridge The suspension bridge The main difference between the three above is the distances they can cross in a single span. A span is measured as the distance between two bridge supports (columns). The beam bridge is basically a rigid horizontal structure resting on two piers, one at each end. The arch bridge is a semicircular structure with abutments on each end. The suspension bridge is one where cables are strung across the obstacle and the deck is suspended from these cables.

The beam bridge The arch bridge The suspension bridge

LARGEST BRIDGES The largest suspension bridge is Akashi-Kaikyo Bridge, Kobe-Naruto Route, Japan. Its span measures 1,991 m (6,529 feets). The bridge was completed in 1999. The longest bridge in the world measured by full length above land or water is the Lake Pontchartrain Causeway. It consists of two parallel bridges that are the longest bridges in the world by total length. The Second Lake Pontchartrain Causeway, which joins Mandeville and Metairie, Louisiana, USA, is 38.422 km (23 miles 1,538 yd) long. It was completed in 1969.

Akashi-Kaikyo bridge

OUR FAVORITE Our favorite bridge is Golden Gate Bridge, San Francisco, USA. It is a suspension bridge, 1.7 miles (2.74 km) long. This bridge was the largest suspension bridge in the world when it was completed in 1937 and it's a symbol of San Francisco.

Golden Gate Bridge - San Francisco, USA