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The Lake Pontchartrain Causeway, sometimes only the Causeway,〔(【引用サイトリンク】 title=The Causeway website )〕 is a causeway composed of two parallel bridges crossing Lake Pontchartrain in southern Louisiana, United States. The longer of the two bridges is long. The southern terminus of the Causeway is in Metairie, Louisiana, a suburb of New Orleans. The northern terminus is at Mandeville, Louisiana. Since 1969, it was listed by Guinness World Records as the longest bridge over water in the world; in 2011 in response to the opening of the allegedly longer Jiaozhou Bay Bridge in China, Guinness created two categories for bridges over water: continuous and aggregate lengths over water. Lake Pontchartrain Causeway then became the longest bridge over water (continuous)〔(Longest bridge over water (continuous length) ), Guinness World Records. Last accessed July 2011.〕 while Jiaozhou Bay Bridge the longest bridge over water (aggregate).〔(Longest bridge over water (aggregate length) ), Guinness World Records. Last accessed July 2011.〕 The bridges are supported by 9,500 concrete pilings.〔(PILE RESTORATION OF THE LAKE PONTCHARTRAIN CAUSEWAY )〕 The two bridges feature a bascule, which spans the navigation channel south of the north shore. ==History== The idea of a bridge spanning Lake Pontchartrain dates back to the early 19th century and Bernard de Marigny, the founder of Mandeville. He started a ferry service that continued to operate into the mid-1930s. In the 1920s, a proposal called for the creation of artificial islands that would then be linked by a series of bridges. The financing for this plan would come from selling home sites on the islands. The modern Causeway started to take form in 1948 when Ernest M. Loeb Jr. envisioned the project. Due to his lobbying and vision, the Louisiana Legislature created what is now the Causeway Commission. The Louisiana Bridge Company was formed to construct the bridge, which in turn appointed James E. Walters Sr. to direct the project.〔(【引用サイトリンク】publisher=http://louisianacivilengineeringconference.org/ )〕 The original Causeway was a two-lane span, measuring in length. It opened in 1956 at a cost of $30.7 million. A parallel two-lane span, 1/100th of a mile (15 m) longer than the original, opened on May 10, 1969, at a cost of $26 million. Since its construction, the Causeway has operated as a toll bridge. Until 1999, tolls were collected from traffic going in each direction. To alleviate congestion on the south shore, toll collections were eliminated on the northbound span. The standard tolls for cars changed from $1.50 in each direction, to a $3 toll collected on the North Shore for southbound traffic. The opening of the Causeway boosted the fortunes of small North Shore communities by reducing drive time into New Orleans by up to 50 minutes, bringing the North Shore into the New Orleans metropolitan area. Prior to the Causeway, residents of St. Tammany Parish used either the Maestri Bridge on U.S. Route 11 or the Rigolets Bridge on U.S. Route 90, both near Slidell, Louisiana; or on the west side, via U.S. Route 51 through Manchac, Louisiana.〔(【引用サイトリンク】publisher=http://louisianacivilengineeringconference.org/ )〕 After Hurricane Katrina on August 29, 2005, videos collected showed damage to the bridge. The storm surge was not as high under the Causeway as it was near the I-10 Twin Span Bridge, and damage was mostly limited to the turnarounds.〔 A total of 17 spans were lost. Structural foundations remained intact. The causeways have never sustained major damage of any sort from hurricanes or other natural occurrences, a rarity among causeways. The existing fiber optic cable plant was blown out of its tray but remained intact per optical time domain reflectometer (OTDR) analysis. With the I-10 Twin Span Bridge severely damaged, the Causeway was used as a major route for recovery teams staying in highlands to the North to get into New Orleans. The Causeway reopened first to emergency traffic and then to the general public - with tolls suspended - on September 19, 2005. Tolls were reinstated by mid-October of that year. The Lake Pontchartrain Causeway is one of seven highway spans in Louisiana with a total length of or more. The others are, in order from longest to shortest, the Manchac Swamp bridge on I-55, the Atchafalaya Basin Bridge on I-10, the Louisiana Highway 1 Bridge, the Bonnet Carré Spillway Bridge on I-10, the Chacahoula Swamp Bridge on U.S. 90, the Lake Pontchartrain Twin Spans on I-10, and the LaBranche Wetlands Bridge on I-310. The Maestri Bridge comes close, but runs short by two-tenths of a mile at roughly in total length. Louisiana is also home to the Norfolk Southern Lake Pontchartrain Bridge, which at is one of the longest railway bridges in the United States. The southern end of the Manchac Swamp Bridge (on the western edge of Lake Pontchartrain) is the western end of the I-10 Bonnet Carré Spillway Bridge (on the southwestern edge of Lake Pontchartrain), and the northern end of the LaBranche Wetlands Bridge is the eastern end of the I-10 Bonnet Carré Spillway Bridge; so these three bridges, by name, are in fact one contiguous bridge. The total driving distance on continuous elevated roadway is over . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lake Pontchartrain Causeway」の詳細全文を読む スポンサード リンク
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