中文摘要：

为了明确传统公路平、纵线形分离设计思想存在的不足及对行车安全的影响,从公路三维线形本质出发,采用空间曲率和挠率对现有线形几何特性进行描述,建立了基于二维设计要素的公路三维线形描述模型;利用SPSS分别建立了高速公路和双车道公路相邻路段平均曲率差、挠率差与事故率之间的关系模型。研究结果表明：公路线形设计时平纵线形的叠加并不能保证组合线形在三维空间中的连续性,当二维线形要素变化时,组合线形的连续性会存在不同程度衰减;空间曲率和挠率的突变量大小与行车安全强相关,其中曲率的连续对行车安全起主导作用,公路真三维线形设计应至少保证二阶几何连续。

英文摘要：

To define the deficiencies of traditional highway horizontal and vertical separated design practice and the effect on traffic safety, spatial curvature and torsion were adopted to describe the geometric properties of current alignments on the basis of the nature of highway three- dimensional alignment, and highway three-dimensional alignment geometric description model was developed based on the two-dimensional design elements. Using SPSS software, the relationship model of the mean curvature and torsion differences with accident rates on adjacent segments of expressways and two-lane highways was developed. The results show that superposition of horizontal and vertical alignments can＇t guarantee geometric continuity in three- dimensional space, and the geometric continuity will degradation in different degrees when the two-dimensional design elements change. The sudden change amounts of curvature and torsion have a strong correlation with traffic safety; in which curvature continuity plays a leading role. Highway three- dimensional alignment design should satisfy the second-order geometric continuity at least.