桥台锥体顺桥轴方向坡率和横断面方向坡率是不同的。因此,在不同方位上边坡率随之变化。锥体是椭圆锥的一部份。根据常用的放样方法(双点双距法、纵横等分法、双圆投影法、支距法)放样出来的图形是椭圆,这对桥台锥体坡脚基在同一标高附近,放样的精度是足够的。但在山区铁路,桥台常常位于山坡 Bridge abutment along the bridge axis direction of the slope and cross-sectional direction of the slope is different. Therefore, the slope rate changes in different directions. Cone is part of an elliptical cone. According to the common lofting method (double-point double-distance method, vertical and horizontal bisection method, double-circle projection method, distance method) out of the figure is elliptical, which is on the bridge abutment cone foot near the same elevation, Is enough. But in the mountain railway, abutment is often located on the hillside