@Pluma 20 August 2020 edited

Crossing Over

"Have you ever thought about how important a bridge is? After all,without bridges,how would people get across rivers and wide gorges.? Bridges are an essential part of out transaportation system for moving people and goods.

The first bridges were simply trees that fell o were place across water or canyons.The wood was strong enough to bear the weight of a person or two at a time,but not carrying heavy loads,People made bridges by stretching rope cable across an open area.In China and other places,rope bridges are still used.They're strong enough to hold people and pack animals with light loads.

Later,people built arch bridges by wedging together large blocks of stone to form a half circle.Arch bridges are among the strongest and longest-lasting:some built more than **1,500 years ago** are still being used,even today.People build arch bridges,but usually from concrete,wood or steel. Another kind of bridge is cantilever.It has two independent steelor concrete beams,one extending toward the center of a river from each bank.A third beam is lifted up to connect the beams.**Canada's Quebec Bridge** is one the worlds longest spanning **1,800 feet(549 m)** across the **St.Lawrence River.**

A suspension bridge spans even more space with its roadway hanging from steel cables supported by massive towers.Each cable can hold thousands of pounds of weight.Probably the most familiar suspension bridge is **California' Golden State**,with main span of **4,200 feet(1,280 m**).When completed in **1937**,it was the world's longest,but in **1964**,**New York Verrazano Narrows Bridge** beat that with a span of **4,260 feet (1,1981 m)**.Then in **1981**, And since **1998**,Japan's **Akashi - Kaikyo Bridge** has held the record,with the span of **1,1991 feet (6,529 m)**." What bridge is the longest now? **Photos:© San Juanico Bridge(Phillipines)** Read.Like.Comment. **Subscribe@Pluma**