A log bridge is a

timber bridge A timber bridge or wooden bridge is a bridge that uses timber or wood as its principal structural material. One of the first forms of bridge, those of timber have been used since ancient times. History The most ancient form of timber bridge is ...

that uses logs that fall naturally or are intentionally felled or placed across streams. The first man-made

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

s with significant span were probably intentionally felled

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s. The use of emplaced logs is now sometimes used in temporary bridges used for

logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, truckssoil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

contact and subsequent rot and wood-eating

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

infestation. Longer lasting log bridges may be constructed by using treated logs and/or by providing well drained footings National Parks Conference 1915, p. 59. "If we can design the abutment so that no moisture can collect under the logs the life of the bridge is materially increased." of stone or

concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...

combined with regular maintenance to prevent soil infiltration. This care in construction can be seen in the French bridge illustrated below, which has well locked dry set stone abutments and a footpath leveled with boards.

Various log bridge designs

File:Log bridge - naturally fallen or man felled.jpg, Log bridge over a river in

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

File:Zaire Log Bridge.jpg, Log bridge in

Zaire Zaire, officially the Republic of Zaire, was the name of the Democratic Republic of the Congo from 1971 to 18 May 1997. Located in Central Africa, it was, by area, the third-largest country in Africa after Sudan and Algeria, and the 11th-la ...

, made of multiple parallel logs File:Crossing Nisqually River near Cougar Rock 01.jpg, Log bridge over the Nisqually River, United States, made of one large log with handrail File:Schwarz - Schwarztöbeli IMG 6621.JPG, Log bridge in

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

with flattened top and handrail File:Suchá Belá, Slovenský ráj, 2012, 004.JPG, Log bridge in

Slovakia Slovakia, officially the Slovak Republic, is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the west, and the Czech Republic to the northwest. Slovakia's m ...

with additional boards on top File:Dřevěný most přes potok v Západních Tatrách.jpg, Log bridge in Slovakia with additional logs laid crosswise (a beam bridge) File:Vallorcine footpath bridge 2003-12-13.jpg, Log bridge in

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

with dry set stone abutments and a footpath leveled with boards File:Tibetan log bridge.JPG, Complex

Tibet Tibet (; ''Böd''; ), or Greater Tibet, is a region in the western part of East Asia, covering much of the Tibetan Plateau and spanning about . It is the homeland of the Tibetan people. Also resident on the plateau are other ethnic groups s ...

an log bridge made of multiple logs (a cantilever bridge)

External links

References

{{DEFAULTSORT:Log Bridge Bridges by structural type Beam bridges Footbridges