高等级公路是国家公路网的骨干,在国民经济发展中具有重要的作用。它主要供汽车高速行驶,要求提供最大的通行能力和最佳的服务水平,线形设计要求高度重视汽车行驶的安全、效率、经济和舒适,尽可能满足和发挥汽车运输的特点。对高等级公路的勘测设计显然不能沿用过去测设低等级公路那一套方法,而需要研究和选用手段比较先进、理论比较严密、能实现多方案比选论证、精度好、效益高的方法,以期设计出的公路能具有显著运输效率,能满足国家在政治、经济和国防各方面的要求和长远利益, High-grade highways are the backbone of the national highway network and play an important role in the development of the national economy. It is mainly used for high-speed vehicles, requiring the maximum capacity and the best service level, the linear design requires a high degree of emphasis on the safety of vehicles, efficiency, economy and comfort, as far as possible to meet and play the characteristics of motor transport. It is obvious that the survey and design of high-grade highways can not follow the method of measuring low-grade highways in the past, and the methods of research and selection are more advanced and the theory is more rigorous. The method of multi-scheme comparison and selection, high accuracy and high efficiency can be realized, With a view to design the highway can have significant transport efficiency, to meet the country’s political, economic and national defense requirements and long-term interests,