六十年代以来,国外开始对使用电子计算机进行纵断面线型的最优化设计作了研究,并且在一定的范围内进行了实验性的使用。实践证明:在减少工程数量、提高设计质量及提高线路设计的自动化程度等方面都取得了较为满意的结果。但是线路纵断面最优化设计是一个比较复杂的问题,涉及的因素很多。它不仅要考虑工程经济的问题,而且要考虑在使用期限 Since the 1960s, foreign countries began to study the optimal design of the profile of the profile using electronic computers, and carried out the experimental use within a certain range. Practice has proved that: in reducing the number of projects, improve the quality of the design and improve the degree of automation of circuit design and so have achieved more satisfactory results. However, the optimal design of the line profile is a complex issue involving many factors. It should not only consider the problem of engineering economy, but also to consider the useful life