0前言我国幅员广袤,地域辽阔,其中69%的国土面积为山区,特别是在西部的12个省市区中,山区所占的比例更是高达75%以上。公路建设项目投资巨大,因此要求在建设项目的决策和设计过程中,必须依据交通需求和公路通行能力,科学确定合理的道路形式。目前正值西部道路建设的高峰期,山区 0 Foreword China has a vast territory and a vast territory, of which 69% of the land area is mountainous. Especially in the 12 provinces and municipalities in the west, the proportion of mountainous areas is as high as 75% or more. The huge investment in highway construction projects requires that in the process of decision-making and design of construction projects, it is necessary to scientifically determine a reasonable road form based on traffic demand and the capacity of roads. At the peak of the western road construction is the mountainous region