The Cogan House Covered Bridge, U.S.A.
|Ancestor||Truss bridge, others|
|Related||Tubular bridge, Skyway, Jetway|
|Carries||Pedestrians, livestock, vehicles|
|Material||Typically wood beams with iron fittings and iron rods in tension|
|Falsework required||Determined by enclosed bridge structure, site conditions, and degree of prefabrication|
A covered bridge is a timber-truss bridge with a roof and siding which, in most covered bridges, create an almost complete enclosure. The purpose of the covering is to protect the wooden structural members from the weather. Uncovered wooden bridges have a life span of only 10 to 15 years because of the effects of rain and sun.
Bridges having covers for reasons other than protecting wood trusses, such as for protecting pedestrians, are also sometimes called covered bridges.
History and development
Early timber covered bridges consisted of horizontal beams laid on top of piles driven into the riverbed. The problem is that the length between spans is limited by the maximum length of each beam. The development of the timber truss allowed bridges to span greater distances than those with beam-only structures or arch structures, whether of stone, masonry, or timber.
Early European truss bridges used king post and queen post configurations. Some early German bridges included diagonal panel bracing in trusses with parallel top and bottom chords. To solve the problem of deterioration of the wood upon exposure to weather, various forms of covering came to be employed.
At least two covered bridges make the claim of being the first built in the United States. Town records for Swanzey, New Hampshire, indicate their Carleton Bridge was built in 1789, but this remains unverified. Philadelphia, however, claims a bridge built in the early 1800s on 30th Street and over the Schuylkill River was the first, noting that investors wanted it covered to extend its life. Beginning around 1820, new designs were developed, such as the Burr, Lattice, and Brown trusses.
Examples of covered bridges
There are about 1600 covered bridges in the world.
- Canada: the Hartland Bridge is the longest covered bridge in the world. In 1900, Quebec, New Brunswick, and Ontario had an estimated 1000, 400, and five covered bridges respectively. By the 1990s there were 98 in Quebec, 62 in New Brunswick, and one in Ontario, the West Montrose Covered Bridge.
- China: covered bridges are called lángqiáo (廊桥), or "wind and rain bridges" in Guizhou, traditionally built by the Dong. There are also covered bridges in Fujian. Taishun County, in southern Zhejiang province near the border of Fujian, has more than 900 covered bridges, many of them hundreds of years old, as well as a covered bridge museum. There are also a number in nearby Qingyuan County, as well as in Shouning County, in northern Fujian province. The Xijin Bridge in Zhejiang is one of the largest.
- Germany: Holzbrücke Bad Säckingen, over the river Rhine from Bad Säckingen, Germany, to Stein, Switzerland (picture), first built before 1272, destroyed and re-built many times.
- Switzerland has many timber covered bridges: Bridge over the river Muota, Brunnen, near Lake Lucerne (picture), Berner Brücke/Pont de Berne over the Saane/Sarine, near Fribourg, (picture), Kapellbrücke.
- USA: The Federal Highway Administration (FHWA) encourages the preservation of covered bridges with its Covered Bridge Manual. There are bridges in California, for example at Knight's Ferry, North Carolina, Pennsylvania, Georgia, Oregon, New Hampshire, New York, Ohio, Alabama, Tennessee, Illinois, Indiana, Iowa, Maine, Maryland, Michigan, Missouri, Connecticut, Massachusetts, Rhode Island, Vermont, Virginia, Minnesota, Wisconsin, and West Virginia.
Other covered bridges
The term covered bridge is also use to describe any bridge-like structure that is covered. For example
- The Lovech Covered Bridge in Bulgaria is covered not for structural reasons, but to accommodate shops.
- The Pont de Rohan in Landerneau, France is one of 45 inhabited bridges in Europe.
- A tubular bridge is a bridge built as a rigid box girder section within which the traffic is carried. Examples include the Britannia Bridge and the Conwy Railway Bridge in the United Kingdom.
- A skyway is a type of urban pedway consisting of an enclosed or covered footbridge between two buildings, designed to protect pedestrians from the weather. For example, the Bridge of Sighs in Cambridge, and Oxford's Bridge of Sighs and Logic Lane covered bridge.
- A jet bridge is an enclosed, movable connector which extends from an airport terminal gate to an airplane, allowing passengers to board and disembark without having to go outside.
- Some stone arch bridges are covered to protect pedestrians or as a decoration as with the Italian Ponte Coperto and Rialto Bridge, and the Chùa Cầu (the Japanese Bridge; picture) in Vietnam.
Covered bridges in fiction
Covered bridges are popular in folklore and fiction.
North American covered bridges received much recognition as a result of the success of the novel, The Bridges of Madison County written by Robert James Waller and made into a Hollywood motion picture starring Meryl Streep and Clint Eastwood. The Roseman Covered Bridge from 1883 in Iowa became famous when it was featured in both the novel and the film. A covered bridge is also prominently featured in the story "Never Bet the Devil Your Head" by Edgar Allan Poe, and covered bridges serve as plot points in the 1988 comedy films Beetlejuice and Funny Farm.
Irgandı Bridge, Bursa, Turkey
A covered bridge in West Sumatra, Indonesia (1877-1879)
"鞘橋" (Saya Bridge) in Kotohira, Japan
Plank-lattice truss interior structure of Green River Bridge in Guilford, Vermont
Covered bridge entrance, Frankenmuth, Michigan
The Russein Bridge (Russeinerbrücke) in Switzerland under construction in 1857. The falsework under the bridge will be removed when the bridge is finished.
- "Covered bridge". Encyclopedia Britannica. Retrieved 8 October 2012.
- "Bridges of Woolwich Township". Woolwich.ca. Township of Woolwich. Retrieved 25 February 2014.
- "Covered Bridge Manual". U.S. Department of Transportation. Retrieved 9 October 2012.
- History/Design Pennsylvania Covered Bridges; accessed 2015.02.26.
- Marshall, Richard G. (1994). "Carleton Bridge". New Hampshire Covered Bridges: A Link With Our Past. Concord: New Hampshire Department of Transportation. OCLC 31182444.
- Kopas, Virginia (30 March 2012). "Pennsylvania is among the tops in the number of covered bridges". Pittsburgh Post-Gazette. Archived from the original on 9 October 2012. Retrieved 9 October 2012.
- "World Guide to Covered Bridges". WoodCenter.org. Iowa State University Institute for Transportation. Retrieved 9 October 2012.
- "Ponts couverts". Transports Quebec. Retrieved 26 September 2012.
- "New Brunswick Covered Bridges". Retrieved 8 October 2012.
- "West Montrose Covered Bridge". Region of Waterloo. Archived from the original on 19 January 2011. Retrieved 31 October 2009.
- "Fujian Bridges!". Amoymagic.mts.cn. 17 January 2004. Retrieved 4 January 2012.
- "Museum of Ancient Bridges, Taishun County". China.org.cn. 27 June 2002. Retrieved 4 January 2012.
- "Langqiao.net" (in Chinese).
- "Swiss Timber Bridges".
- "Covered Bridge Manual". U.S. Department of Transportation. Retrieved 28 November 2012.
- "Knights Ferry SHP: California's Longest Covered Bridge". Retrieved 28 November 2012.
- "North Carolina Covered Bridges". Retrieved 28 November 2012.
- "Covered Bridges in Tennessee". Tennessee Department of Transportation. Retrieved 28 November 2012.
- "Maryland's Six Existing Covered Bridges". Maryland Covered Bridges. Retrieved 1 July 2014.
- "Swamp Meadow Covered Bridge". VisitRhodeIsland.com. Retrieved 11 July 2013.
- "Covered Bridge". Zumbrota Covered Bridge. Retrieved July 16, 2014.
- Chrimes, Mike (1991). Civil Engineering, 1839-1889. London: Alan Sutton. p. 47. ISBN 1-84015-008-4.
- Gesell, Laurence E (1992). The Administration of Public Airports. Chandler, AZ: Coast Aire. pp. 114–115. ISBN 0-9606874-7-5.
- Dégh, Linda, ed. (1980). Indiana Folklore: A Reader. Bloomington: Indiana University. p. 42. ISBN 0253202396.
|Wikimedia Commons has media related to Covered bridges.|
- Covered Bridge Security Manual United States Forest Service
- Use of Laser Scanning Technology to Obtain As-Built Records of Historic Covered Bridges United States Forest Service
- "Covered Spans of Yesteryear", documenting the current and former covered bridges of the United States and Canada
- National Society for the Preservation of Covered Bridges
- Covered Bridge Map, an interactive map showing locations of covered bridges in the United States and Canada
- (French) "Les ponts couverts au Québec, héritage précieux", an article on covered bridges in Quebec