The Running Speed Law and Model under Combined the Effect of both Horizontal and Vertical Alignments

Highway alignment design should make alignments continuous and keep the index balance in order to ensure the security and comfort of the vehicles traveling at a high speed. Alignment-index value of Highway in plain area usually relatively higher. The current standard is based on the method of design-speed from the theory of alignment design which the index is usually given a much looser value scope. This design method has some defects itself. Based on the field survey to collect the value of Running Speed in the highway, this paper has summarized the characteristic of the Running Speed of Highway in plain area and provides the scope of Running Speed in different conditions such as the segment of straight line and curvous line. Based on the statistic-value of the Running Speed, this article has contributed the Running Speed model by the conditions in single alignment of horizontal and vertical and also including their composition.