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The Tomlinson Lift Bridge is a crossing of the Quinnipiac River in New Haven, Connecticut. The bridge forms a segment of U.S. Route 1. The Tomlinson Vertical Lift Bridge carries four lanes of traffic across New Haven Harbor and a single-track freight line owned by the Providence & Worcester Railroad that connects the waterfront with the Northeast Corridor line of Metro North and CSX. A sidewalk is present along the southern edge of the bridge. ==History== The first bridge here was erected in 1797 by Isaac Tomlinson's group to replace profits from their ferry ruined by a new bridge.〔HAER data page 4〕 This -wide covered wooden truss bridge included a draw to allow vessels through.〔 It has also been described as a "wood and sandstone" bridge.〔(【引用サイトリンク】url=http://www.constructionequipmentguide.com/Cianbro-Bridges-Quinnipiac-River/1634/ )〕 The second bridge, 1885-1922, was an iron bridge which was never particularly good, having been salvaged from a scrap yard, and not thought well of even before then.〔 By 1913, this bridge was opening 17,000 times a year.〔 Plans for replacement were created during World War I.〔 The third bridge on-site was a trunioned double-leaf bascule drawbridge with its counterweights in a closed pit underneath, built between 1921 and 1924.〔HAER data page 5〕 It was designed by engineer Ernest W. Wiggin of New Haven in the Beaux-Arts style, based on a bascule design by Joseph B. Strauss.〔〔HAER data page 7〕 Before the completion of the adjacent Q Bridge, it was carrying 30,000 vehicles a day.〔HAER data page 6〕 When closed, clearance under the bridge was at mean high water, ranging from at extreme high tide to extreme low tide.〔 The channel width was , with a total span length between centers of .〔 The builder was the Phoenix Bridge Company of Philadelphia, Pennsylvania.〔HAER data page 13〕 The current bridge, the fourth one on this site, is a lift bridge long and wide, a significant improvement from the previous (third) bridge's channel.〔 The mechanism raises the lift span with counterweights on each of the two towers on either end.〔 The bridge cost $120 million, designed by Hardesty & Hanover LLP of New York City, is wide and long with two tower spans and six -long approach spans.〔(Tomlinson bridge construction notes )〕 The lift span weighs almost with a total load-to-move of . It provides a channel with horizontal clearance and vertical clearance when the span is closed, and an additional vertical clearance when it is open. The project began as a renovation of the third Tomlinson Bridge but evolved into the construction of a totally new structure. Securing the bridge's lift piers initially proved difficult because rock elevation and slope differed along the route. To secure the piers, teeth were welded to the tip of 20-in-diameter pile shells that were then drilled into the bedrock. For some piles, an adequate seal was not achieved until the pile had been seated into 5 ft. of bedrock. 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「Tomlinson Lift Bridge」の詳細全文を読む スポンサード リンク
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