随着交通运输的发展,一些既有线路与道路的交叉需要增建和改建立体交叉。为了不影响既有线的运营,采用顶入预制的箱形框架,可以收到较好的效果。近年来,此法正在不断改进完善,迄今所用顶入法施工的框架,宽度和总长均已达40米左右,而框架顶面至轨底的高度已可压缩至0.4米左右,这在桥梁建筑史上是一个很大的改进。箱形框架桥的结构型式, With the development of transportation, the crossing of some existing lines and roads needs to be built and reconstructed. In order not to affect the operation of existing lines, using prefabricated box-shaped frame, you can receive better results. In recent years, this method is constantly improving and perfecting. Up to now, the framework of top-in construction method used has reached a width of 40 meters and a total length of 40 meters. The height from the top to the rail of the frame has been reduced to about 0.4 meters. History is a big improvement. Box-framed bridge structure type,