The Comprehensive Evaluation Model Of Linear Index For Mountain Low-Grade Highway In Rebuilding And Widening And Its Application

Background of low-grade highway rebuilding project to the mountainous areas ofYunnan to study the alignment indicators of highway. Different from the new highway, themain way to achieve the reconstruction of mountain low-grade road is widen the local sectionor adjust the horizontal and vertical Alignment of local road, therefore, reasonable applicationof horizontal and vertical indicators, so that the traffic safety to be guaranteed, constructioncosts and damage to the environment has been effectively controlled, is an outstandingtechnical problems facing the mountain low-grade highway renovation and expansion.Base on the characteristics of low-level highway reconstruction projects in mountain,analysis of factors affecting highway alignment indicators on the three aspects of road trafficsafety, environmental impact and road-building economic costs, horizontal and verticalindicators of local sections for the object, safety、environmental and construction costs for theconstraints, using the analytic hierarchy process to establish a three-level indicators of sevenevaluation factors mountain low-grade highway alignment indicators comprehensiveevaluation system, among them with the traffic security layer,the environmental impact layer,economic layer three level as secondary index layer,level3index is in the secondary indexselection of impact assessment of factors. Based on Fuzzy theory, to quantify factors thatill-defined or difficult to quantitative of the road alignment indicators evaluation. Inestablishing evaluation weight set, using the analytic hierarchy process, scientific andreasonable to reflect the index importance degree and the index of the difference between thedegree.By analyzing the characteristics of Yunnan highway development and environment, andin combination with the actual situation of the project, select the23typical sections, redesignthese sections by using the indicators which near the specification limit or ultra-specificationlimit. Using of mountain highway alignment index comprehensive evaluation model,toevaluate the impact of traffic safety, environmental impact and economic of the23section inusing different linear index.According to the analysis of the evaluation results, we can get the following conclusions:In the mountain road highway horizontal alignment design, should be caution to chose to thelimit of standard index, for ultra specification of indicators should be combined withengineering, critical review of the feasibility of the indicators; In process of back curve design, for the adoption of ultra-specification indicators should accord to the actual situation, basedon the principle of protection of the natural ecological environment, where appropriate; Inthe vertical alignment design, downhill section near the specification limit indicators shouldbe used with caution；In the short length of slope sections, the slope near the specificationlimit or ultra-specification limit, flexible adopt the specification limit index orultra-specification index in accordance with the actual situation of the project.