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Sosrobahu is a road construction technique which allows long stretches of flyovers to be constructed above existing main roads with a minimum of disruption to the traffic. The technique was designed by Tjokorda Raka Sukawati and involves the construction of the horizontal supports for the highway beside the existing road, which is then lifted and turned 90 degrees angle before being placed on the top of the vertical supports to form the flyover pylons. This technique is of considerable value in increasing road mileage in large cities where there is a restricted space for new roads and where the closure of existing roads for the length of time to build a flyover using normal construction techniques would impose significant economic costs. ==Background== By the 1980s, Jakarta was experiencing increased traffic congestion, and flyovers were seen as one solution to the improving transport infrastructure. One construction company operating at that time was PT Hutama Karya, which was granted a contract to build a highway above bypass A Yani, an extremely important stretch of highway where it was vital that the road would continue to be open to traffic throughout the period of construction. In addition to this challenge, PT Hutama Karya were also granted a contract to build a flyover between Cawang and Tanjung Priok in 1987. The most difficult issue was the requirement to support the road with a row of concrete pylons (pier shafts) 30 m apart, on top of which would sit the 22 m wide road supports. The vertical pier shafts were to be sextagonal in shape with a diameter of 4 m, and were to sit in the central lane of the existing road. The erection of the pier shafts was not difficult; what caused problems were the poured concrete pier heads. With conventional construction techniques, the pier heads would be moved into place with the help of iron supports beneath the outspread pier heads, but the use of iron supports would necessitate the closure of the road below. Another option was to support the pier heads from above, but this increased the costs of the project. In response to these problems, Sukawati had the idea of initially erecting the concrete pier shafts and then building the poured concrete pier heads in the centre lane, parallel to the existing roadway, and then raising and turning the pier heads 90 degrees into place. The only problem with this idea was that the pier heads weigh approximately 480 tonnes each. 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「Sosrobahu」の詳細全文を読む スポンサード リンク
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