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overhead line crossing : ウィキペディア英語版 | overhead line crossing
An overhead line crossing is the crossing of an obstacle—such as a traffic route, a river, a valley or a strait—by an overhead power line. The style of crossing depends on the local conditions and regulations at the time the power line is constructed. Overhead line crossings can sometimes require extensive construction and can also have operational issues. In such cases, those in charge of construction should consider whether a crossing of the obstacle would be better accomplished by an underground or submarine cable. ==Crossings of roads and railway lines== Overhead line crossings of roads, railway lines, and small- and medium-sized watercourses do not normally require special construction. However, in the first years of overhead line building a scaffold under the line was required, when a railway line or a road was crossed. Later in Germany and some other countries on each end of a powerline crossing of a state-operated railway a dead-end tower was required, which can still be seen on some old power lines. For overhead line crossings of motorways the pylons must be rebuilt before they wear out, because these demand additional maintenance. If local conditions are appropriate, an overhead line can be implemented by way of a valley bridge. For example, the Koersch valley bridge near Esslingen, Germany carries the 110 kV, three-phase line of the EnBW AG with 2 circuits. Because of the danger of short circuits from falling objects, undercrossings are typically avoided.
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「overhead line crossing」の詳細全文を読む
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