The invention relates to an overpass which is a crossroad three-layer overpass. The overpass is provided with sixteen lanes. The sixteen lanes comprise four straight lanes, four right turning lanes, four left turning lanes and four turning lanes. The overpass has three layers, the ground of the first layer is a pedestrian path, and the ground of the second layer and the third layer are vehicle passing paths. The contour of the three-layer bridge surface of the overpass is #-shaped. And the third-layer bridge surface is a twenty-sided shape enclosed by twenty line segments. A fourteen-sided courtyard enclosed by fourteen line segments is arranged in the three-layer bridge surface of the overpass. The overpass shown in the figure 1 and the figure 2 is provided with twelve lanes passing through three layers of bridge floors. And the turning parts of the four left turning lanes and the four turning lanes of the overpass are arranged on the three-layer bridge surface. Four right turning lanes of the overpass are arranged on the second-layer bridge floor in the whole process. The overpass shown in the figure 3 and the figure 4 is provided with eleven lanes passing through the three layers of bridge floors. And the turning parts of the four left turning lanes and the three turning lanes of the overpass are arranged on the three-layer bridge surface. Four right turning lanes of the overpass and a turning lane of a north coming vehicle are arranged on the second-layer bridge floor in the whole course. The overpass is not provided with ramps.

本发明所述立交桥，为十字路口三层立交桥。立交桥设置十六条车道。十六条车道是：四条直行车道、四条右拐弯车道、四条左拐弯车道、四条调头车道。立交桥有三层，一层地面为人行通道，二层和三层为车辆通行通道。立交桥三层桥面轮廓是井字形状。三层桥面，是由二十条线段围成的二十边形。立交桥的三层桥面内，有一个由十四条线段围成的十四边形天井。图1和图2所示立交桥有十二条车道经由三层桥面。立交桥的四条左拐弯车道，四条调头车道的拐弯部位均在三层桥面。立交桥的四条右拐弯车道，全程在二层桥面。图3和图4所示立交桥有十一条车道经由三层桥面。立交桥的四条左拐弯车道，三条调头车道的拐弯部位均在三层桥面。立交桥的四条右拐弯车道，北向来车的调头车道全程在二层桥面。立交桥没有匝道。