Research On Serviceability Evaluation And Optimization Of Construction Resources Of Rural Road Network

As an important part of the road network,rural roads are the primary public welfare infrastructure to support the construction of new socialist countryside and play a vital role in promoting the economic development of rural areas.China's rural roads have experienced rapid development in the past 30 years and have formed a huge road network nowaday.In the face of rural road networks with complex topologies and unbalanced regional development,how to develop a targeted evaluation and optimize the limited construction resources for supporting the social and economic development in rural areas has become a focus issue of relevant government departments and research institutions.Under the circumstances above,this thesis takes rural roads as the object of the research and focus on two key problems including the serviceability evaluation of rural road network and the allocation optimization of construction resources.The research has significant theoretical and engineering value.The main research contents of the thesis are as follows:(1)On the basis of clarifying the serviceability of rural road network,we combine the characteristics of rural roads used to connect administrative nodes and traffic nodes at all levels in rural areas,establishe an evaluation index system for rural road network serviceability including road network scale and spatial distribution,road network service capacity,road network management and road network operation.The evaluation index system assesses the matching degree between rural roads and regional economic and social development from static and dynamic levels.Furthermore,analytic hierarchy process and fuzzy comprehensive evaluation method are used to integrate multiple indicators in the evaluation index system to achieve comprehensive evaluation of single indicator.(2)Using the massive basic data of rural roads in Guangdong Province from 2012 to 2017,we make an in-depth and systematic evaluation of the development status of rural road construction and serviceability of rural road network in the order of province,regions(the Pearl River Delta,East of Guangdong,West of Guangdong,North of Guangdong)and cities(21 cities in total).The results show that the rural roads in various regions of Guangdong Province have the characteristics of uneven development.The rural roads in the Pearl River Delta region are obviously superior to other regions,and there are also obvious differences between the different cities in the eastern,western and northern regions where the development is relatively backward.(3)In order to ensure that the rural road planning can meet the desired service and the limited investment budget,we establishe a bi-level planning model for optimal allocation of rural road construction resources considering road network capacity and traffic equilibrium.The proposed model takes the minimum saturation of the road network considering the future traffic volume as the optimization goal,and is constrained by investment budget and road service level.Meanwhile,we design a decision variable data structure that represents the road construction plan in the form of ‘Construction Cost-Design Capacity-Design Speed'.The data structure comprehensively considers the factors such as the cost,benefit and level of service of rural road construction,and provides a unified carrier for realizing the calculation of the plan.(4)In order to solve the bi-level planning model for optimal allocation of rural road construction resources,a model solving algorithm based on genetic evolution and Logit multipath traffic assignment was presented.Based on the limited rational behavior of traffic participants,the Logit-based multi-path traffic assignment algorithm is used to solve the lowerlevel planning model with the minimum total impedance of the road network as the target under fixed demand.When constructing the fitness function of the genetic algorithm,the investment constraint penalty factor and the road service level constraint penalty factor are introduced to reducing the fitness value of chromosomes that do not meet the constraints(instead of directly eliminating it).This method preserves the diversity of chromosomal genes and improves the probability that the genetic algorithm obtains a relatively optimal solution.Taking a road network of a township in Zhanjiang City,Guangdong Province(including 25 links,18 nodes)as an example for case calculation,the experimental results show that the proposed model and algorithm have high accuracy and reliability.