Timber Bridge

a bridge with wooden spans and supports. Timber bridges may also have concrete supports. The art of building timber bridges was highly developed in ancient Rome. In the chronicles of the llth and 12th centuries there is frequent mention of bridges built in Russia across large rivers. There are different timber-bridge systems in the USSR. It is practical to build them in regions rich in timber. Where the spans are 6-8 m, the simplest beam systems are used, while spans of 10-18 m require composite or bonded girders or a bracing system. Spans from 16 to 50 m are covered by span structures with trusses. Timber bridges are usually made from the wood of coniferous varieties (pine, fir, and larch), with important parts made of oak. Timber bridges are treated with antiseptics to prevent rotting.