在实际勘测与选定铁路和公路时，需要设置横断面。在直线路段，这一工作是按一般方法进行；而在曲线上横断面的设置则比较复杂一些，因为这时的横断面应当在曲线半径的延长线，（法线）上。要知道，在山坡路段，横断面稍稍偏离半径方向，就会使横断面发生显著的变化，从而造成土方设计上不正确的计算。 In the actual survey and selected rail and road, you need to set the cross-section. In a straight line, this work is done in the usual way; while setting the cross-section on the curve is more complicated because the cross-section should be on the extension of the curve radius (normal). You know, in the hillside section, the cross section slightly deviates from the radial direction, it will make significant changes in the cross-section, resulting in earthwork design incorrect calculation.