shaahin and feryal's bridge info

special types of bridges are defined according to function. To ensure the strength and durability of bridges and other structures they design.Bridges are structures used by people and vehicles to make crossing areas easier in travel. Engineers build bridges over rivers, lakes, ravines, canyons, railroads, and highways. To build a strong bridge we must be built strong enough to safely support their own weight as well as the weight of the people and vehicles that pass over it. To make a strong bridge some parts should be designed triangular.The bridge should be very strong to hold windstorms, weathering, earthquakes, freezing and thawing.
This is a useful site: www.roadstothefuture.com/Coleman_Bridge.html

done by:Shaahin, Feryal