一、问题的提出四级公路平曲线上路面加宽常见的几何布置型式有如图1、图2所示两种。图1的加宽渐变段仅仅设在直线缓和段L_s范围内,呈三角形,故称之为三角型,即在圆曲线范围内路面加宽为不变的全加宽值W,圆曲线两端设置加宽缓和段,其加宽值由直线段加宽为零按直线比例逐渐增加到圆曲线起点处 First, the question raised Four-level highway flat curve on the road surface to broaden the common geometric layout shown in Figure 1, Figure 2 shows two. The widening and gradual change section in Fig. 1 is only located in the range of the straight-line easing section L_s, which is triangular. Therefore, it is called the triangular type, that is, the widening value W is constant in the circular curve, Set to widen the easing section, the widening value is widened by the straight line segment to zero by a straight line gradually increased to the starting point of the circular curve