Research On Methodology For Highway Maintenance And Rehabilitation Decision-making Based On Integrated Asset Management

China has constructed a tremendous highway infrastructure system;thus,for road agencies,it is increasingly and highly required to maintain and manage a variety of highway assets such as sub-grade,pavement,bridge and tunnel structures,and roadside facilities economically and efficiently.In the traditional separate-managed highway asset management,the overall consideration of other highway infrastructure assets and highway network are often neglected in maintenance and rehabilitation(M&R)planning;hence,while the optimal decision of each highway asset can be made,the summation of them cannot achieve the optimal M&R solution of the total highway network.To bridge this gap,inspired by integrated asset management,numerous researchers conducted studies focusing on highway M&R planning and decision-making following an integrated asset management manner in the past decades.However,most of these works just conducted M&R decision-making and resource or budget allocation for various highway assets infrastructure on the same platform simultaneously,but neglected the asset dependence among each asset classes.Therefore,it is still unable to truly achieve the real overall optimal M&R decisions for the total highway network system.To this end,this study proposed a methodology for highway network M&R planning based on integrated asset management considering asset dependence.First,the asset dependence in the highway network is summarized and analyzed.Specifically,three prerequisites for highway network M&R planning and decision-making following integrated asset management were presented.First,it requires a comprehensive network condition performance metric for the overall highway network system that reasonably incorporates various classes of highway infrastructure assets.Second,it needs to appropriately consider the traffic redistribution in the highway network during the M&R duration and its impacts on the M&R planning and decision-making.Third,it entails to adopt a reliable and robust decision-making methodological framework that can comprehensively analyze and determine M&R projects treatments for different highway asset infrastructures.Further,on the basis of the requirement of employing a comprehensive network condition performance metric for the overall highway network,and based on the current highway technical condition evaluation system in China,the evaluation index for the technical condition of the sub-grade,pavement,bridges,tunnels,culverts,and traffic facilities,as well as the integrated overall condition performance index for the technical condition of the highway network that comprehensively considers the multiple highway assets infrastructure were presented and analyzed.Then,based on the the requirement of reasonably considering of the traffic redistribution of the highway network system during highway M&R interventions,first,the influence of implementing different types of highway M&R activities regarding diverse highway infrastructure assets,including sub-grade,pavement,bridges,tunnels,culverts,and traffic facilities were analyzed.Subsequently,pavement,bridge,and tunnel M&R interventions were considered,and the associated impacts of implementing these M&R projects on the distribution of traffic flow in the highway network were analyzed respectively.With this regard,a model calculating highway segment capacity,a generalized traffic impedance function model,and a traffic assignment model based on stochastic user equilibrium(SUE)during implementing M&R interventions were developed subsequently.Also,an algorithm based on the Self Regulated Method of Successful Averages(SR-MSA)was employed to solve the SUE problem.Besides,based on the requirements of using a comprehensive methodological framework for highway network integrated asset management,a model for M&R decision-making objectives including agency cost,network performance,user cost,and environmental impact were established respectively.Considering the impact of traffic redistribution on various decision-making objectives during implementing highway M&R interventions,a bi-level multi-objective optimization(MOO)model for highway network integrated asset management M&R planning and decision-making was developed.Specifically,the upper model was set to MOO model optimizing the proposed four decision-making objectives,and the lower model was set to a SUE model on the basis of the determined M&R plan from the upper model.To better consider the relationship between various objectives,a posteriori optimization method was selected for solving the MOO problem.A reference point based Non-dominated Sorting Genetic Algorithm III(NSGA III)and SR-MSA were adopted to solve the bi-level MOO model and to generate Pareto solutions.Then,a weighted-sum method,normalization and analytic hierarchy process(AHP)were used to determine the final satisfactory solution.Finally,to demonstrate the effectiveness and feasibility of the proposed method in this study,a 5-year case study was conducted based on an real highway network in China,focusing on pavements and bridges.A bi-level MOO model was established and a 4-objective Pareto solution set was generated using NSGA III and SR-MSA.Then,the trade-off analysis between agency costs and network performance,user cost,and environmental impact was conducted subsequently.Based on the results of trade-off analysis,the Pareto solutions were normalized,and satisfactory solutions were then obtained using weighted-sum method and AHP.By comparing various decision objectives of the highway network system during the planning horizon of the satisfactory solution and the non-M&R case,the M&R investment benefit level of the preferred satisfactory solution was further evaluated.The results of the case study can greatly prove the effectiveness and feasibility of the proposed method for highway network M&R planning based on integrated asset management.In the decisionmaking for integrated asset management based M&R planning,it enable to assist decisionmakers in making M&R decisions that have a high cost-effectiveness,are people-oriented,environmentally friendly,and resource saving.In conclusion,the research results demonstrated that the methodology proposed in this study enable to meet the needs of the development of China’s highway infrastructure system,support the intelligent decision-making of China’s highway infrastructure assets management,and provide a new feasible direction of China’s highway network system M&R decisionmaking and planning based on integrated asset management.Furthermore,compared with existing research,this study has the following innovations and contributions:(1)a methodological framework with optimization model,and solution algorithm for the highway network M&R planning based on integrated asset management considering asset dependence was established;(2)a bi-level optimization model reasonably integrating traffic assignment into the decision-making of highway M&R planning was established to better consider the impact of different types of highway M&R projects on the traffic distribution of the overall highway network,which;(3)a MOO model for highway M&R decision-making was established,taking into account objectives of agency costs,network performance,user costs,and environmental impacts,in which Pareto trade-off analysis analysis could be conducted through NSGA III,and more people-oriented and environmentally friendly M&R decisions could be hence generated.