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The Jamaica Line (also known as the Broadway Line or Broadway (Brooklyn) Line) is an elevated rapid transit line of the B Division of the New York City Subway, in Brooklyn and Queens, New York City, United States. It runs from the Williamsburg Bridge southeast over Broadway to East New York, Brooklyn, and then east over Fulton Street and Jamaica Avenue to Jamaica, Queens. In western Jamaica, the line goes into a tunnel, becoming the lower level of the Archer Avenue Line in central Jamaica. The and trains serve the entire length of the Jamaica Line, and the serves the line west of Myrtle Avenue. The longest elevated line in the system, the Jamaica Line includes the oldest existing elevated structure in the subway system - the original 1885 line of the Brooklyn Elevated Railroad, the BMT Lexington Avenue Line - between Gates Avenue and Van Siclen Avenue, as well as the newest elevated structure - the 1988 ramp into the underground Archer Avenue Line. When the Brooklyn–Manhattan Transit Corporation (BMT) operated the line railroad directions were east and west, generally in agreement with compass direction. However under NYCT, the directions used are north and south, which replaced the BMT's old west and east respectively. This reclassification resulted in services which ran through the BMT Nassau Street Line to Downtown Brooklyn having two south ends. To eliminate any confusion, the directions of train services in the eastern division were switched, with trains running towards Jamaica being considered Northbound.〔The service table on the 1967 New York City Rapid Transit Map and Station Guide refers to southbound a.m. skip-stop service on the and .〕 The (later K) and current services were an exception to this, with Jamaica or Metropolitan Avenue remaining the south terminal, since they used the Chrystie Street Connection from the Jamaica Line to the IND Sixth Avenue Line. == Description == The Jamaica Line includes a variety of structures. The original BMT Jamaica Line started from Broadway Ferry, Brooklyn. The line was two tracks, and connected with Marcy Avenue, from the west. This section, which was called the "Broadway Spur", has a short, but easily seen remnant (about one-half of a block in length, no tracks, just maintenance buildings) west and south of where the line curves toward the Williamsburg Bridge. From Marcy Avenue to a point just before Alabama Avenue the line operates on the structure of old elevated railways, but substantially rebuilt and upgraded to a three-track line around World War I under the Dual Contracts of 1913. From Alabama Avenue to just before the current Cypress Hills station, the Jamaica Line operates on the oldest elevated structure in New York City, a steel-reinforced cast iron line opened in 1893. Interestingly enough, west of Alabama Avenue, a third middle trackway exists and elevates over the other two tracks, ending just west of the Alabama Avenue station. This track was intended to be an express track, but engineering studies completed after the work started indicated that the vibration of trains passing over the stations would be too severe and would literally shake the stations apart. Between Crescent Street station and Cypress Hills, the line runs on an "S-curve", turning north from Fulton Street onto Crescent Street, then east onto Jamaica Avenue. The curves are at nearly-90 degree angles, forcing trains to drastically reduce speed to 15 miles per hour in order to traverse them. The line east of Cypress Hills is known as the Jamaica Avenue Line, the newest section of the line which was built under the Dual Contracts. This structure has provisions on its entire length for three tracks,〔New York Times, (New Subway Line: Affords a Five-Cent Fare Between Manhattan and Jamaica, L.I. ), July 7, 1918, page 30〕 but a center track was never built, with the exception of a layup track at 111th Street and another between 160th Street and 168th Street on the now-demolished original end of the line. Four curves on the line, including the two on the Jamaica Avenue "S-curve", rank among the 30 sharpest curves in the subway system.〔 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「BMT Jamaica Line」の詳細全文を読む スポンサード リンク
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