The Research Of Risk Assessment Method In Road Alignment Based On Risk Implicit Factors

Highway route design is not only the key to highway construction, but also the main content in overall planning, pre-feasibility study, feasibility study and design stage. However, due to subjective effects of uncertainties exist in design stage,there are certain risks of traditional design methods for line programme choices. Once designer’s subjective analysis was mistaken, passive acceptance generated by the qualitative analysis would form lone-term and sustained adverse impact to project construction.The concept of risk assessment in the design of road alignment was introduced in this passage, which would be improved as an important parameter in stage of feasibility analysis. Combined with engineering practice of construction and operation periods, an applicable set of risk evaluation system was built. The system can be more objective in analysis of uncertainties that exist in the design process.The result can provide a reference for designers to improve the designer’s subjective uncertainty, and to achieve the purpose of reduce subjective errors and project’s risk.The article was mainly to complete the following contents:1、Based on the summary of the risk and related concepts, concept of "risk implicit factor" was proposed. And subjective influencing degree of the factors on classification of "quality"and"quantity"impact factor in road alignment stage was explicated.2、Through reverse thinking of risk identification, An HOI(hidden-out-in)risk identification model based on "environmental"and"economic" implicit factors was proposed. Various risk factors involved in design phase of road alignment, that would impact decision-makers subjectively and result in the increase of dominant/hidden cost, were analysized.3、Based on the HOI-risk-identification model and actual situation of engineering, evaluation index system of subjective impact factors in the stage of selection design was established in accordance with multi-level pyramid’s progressive distribution mode.4、Take advantage of optimized AHP(Analytic Hierarchy Process) combined with traditional AHP and BP neural network, a comprehensive risk evaluation model was established.The model could determine the risk impact of the indicators for the selected line program,which would be more scientific and rational in assisted in decision maker’s work. 5、Typical road selections of Shenhai Expressway were selected as examples to discuss the feasibility of this risk assessment methodology in the design of road alignment.