Covered bridge

Covered Bridge

The Cogan House Covered Bridge, U.S.A.
Ancestor	Truss bridge, others
Related	Tubular bridge, Skyway, Jetway
Descendant	None
Carries	Pedestrians, livestock, vehicles
Span range	Short
Material	Typically wood beams with iron fittings and iron rods in tension
Movable	No
Design effort	Low
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 lifespan 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 and keeping horses from shying away from water, are also sometimes called covered bridges.

History and development

Baumgardener's Covered Bridge, showing the truss protected by the covering

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.

In the mid-1800s, the development of cheaper wrought iron and cast iron led to metal rather than timber trusses, except in those areas of plentiful large timber.

Examples of covered bridges

Buchfart - Alte Holzbrücke 1613

There are about 1600 covered bridges in the world.

Asia

• 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.

Europe

• 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.

North America

Canada

The 1,282-foot (391 m) Hartland Bridge in New Brunswick 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.

United States

According to Covered Bridges Today by Brenda Krekler, as many as 12,000 covered bridges once existed in the United States; that number dropped to under 1,500 by the 1950s. The National Society for the Preservation of Covered Bridges was formed in 1950.

The Federal Highway Administration (FHWA) encourages the preservation of covered bridges with its Covered Bridge Manual.

Today, covered bridges exist in several states:

• Alabama — see list of covered bridges in Alabama
• California — eleven were reported in 2002, including one at Knight's Ferry
• Connecticut — several wooden covered bridges exist over the Housatonic River
• Delaware - Three bridges remain in New Castle county.
• Georgia — see list of covered bridges in Georgia (U.S. state)
• Illinois — five covered bridges remain in the state, most notably the Red Covered Bridge north of Princeton
• Indiana — In 1980, Indiana was reported as having 130 extant covered bridges, with the highest number (36) in Parke County. See list of covered bridges in Indiana.
• Iowa — Nineteen covered bridges were built in Iowa between 1855 and 1885; nine remain, five of which are in Madison County around Winterset (see List of covered bridges in Madison County, Iowa).
• Maine — see list of covered bridges in Maine
• Maryland — six remain as of 2015
• Michigan — see list of covered bridges in Michigan
• Missouri — see list of covered bridges in Missouri
• Minnesota — see list of covered bridges in Minnesota
• Massachusetts — see list of bridges on the National Register of Historic Places in Massachusetts
• New Hampshire — At one time there were about 400 covered bridges in New Hampshire. It was reported that "at the end of twentieth century there were still nearly seventy covered bridges in New Hampshire." In 2006, it was reported that there are 54 surviving bridges administered by the New Hampshire Department of Transportation, the most famous being the Cornish–Windsor Covered Bridge (1866), spanning the Connecticut River from Cornish, New Hampshire to Windsor, Vermont; this bridge is the longest wooden covered bridge in the United States. See list of covered bridges in New Hampshire.
• New Jersey — New Jersey had up to 35 covered bridges at its peak; many that were destroyed or damaged in various major floods are rebuilt as metal truss bridges. Today, two covered bridges remain: Green Sergeant's Covered Bridge (19th century) and Scarborough Bridge (1959).
• New York — see list of covered bridges in New York
• North Carolina — two remain, the Pisgah and Bunker Hill
• Ohio — 142 remain, the second-highest of any state, down from over 4,000 at peak. See List of covered bridges in Ohio.
• Oregon — see list of covered bridges in Oregon
• Pennsylvania — about 219 remain, the most of any state. See List of covered bridges on the National Register of Historic Places in Pennsylvania.
• Rhode Island — see list of covered bridges in Rhode Island
• Tennessee — four remain as of 1980
• Vermont — "Vermont is justly famous for her covered bridges. No other state has built and still possesses so many of the old timbered crossings in so small an area." In 1996, 106 covered bridges were reported in Vermont. See list of covered bridges in Vermont.
• Virginia — see list of covered bridges in Virginia
• Wisconsin — The only remaining historic covered bridge in Wisconsin is the covered bridge in Cedarburg. There is also the Smith Rapids Covered Bridge in Park Falls, but it was built in 1991.
• West Virginia — see list of covered bridges in West Virginia

Other bridges that are covered

Pont de Rohan

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 and the The Pont des Marchands in Narbonne are two 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 1992 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.

Gallery

• 

  Covered Bridge at Bowie Race Track

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  West Dummerston Covered Bridge

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  Holzbrücke, Bad Säckingen

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  Kapellbrücke, Luzern

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  Oldest covered railroad bridge in the United States is located at Hopkinton, New Hampshire.

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  Covered bridge at the Cole Land Transportation Museum in Bangor, Maine

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  Hartland Bridge

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  Corbin covered bridge over North Branch where it enters the Sugar River in Newport, NH

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  Chengyang Bridge

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  Xijin Bridge in Zhejiang, China

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  A covered bridge in West Sumatra, Indonesia (1877-1879)

• 

  Saya Bridge in Kotohira, Japan

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  Plank-lattice truss interior structure of Green River Bridge in Guilford, Vermont

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  Covered bridge entrance, Frankenmuth, Michigan

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  The Russein Bridge (Russeinerbrücke) in Switzerland under construction in 1857. The falsework under the bridge was removed after the bridge was finished.

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  Rosenman Covered Bridge, in Madison County, Iowa

External links

• 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