Research On Integrated Planning For Hub-and-spoke Aviation Network And Fleet Considering Operation And Time Cost

While the civil aviation industry has been promoted to transfer from high-speed development to high-quality development,China is putting effort to improve the connectivity between cities and travel convenience of small-medium cities.The existing point-to-point route structure can not fully cover all travel demands,resulting in the inadequate air routes of airports in small-medium cities can only meet a small part of market demands.Presenting a highly discrete state,the passenger demand is limited to form a scale so as to result in the problems such as low flight frequency and high time-cost of passengers’ waiting time.Thus,large airlines need to transfer their strategy of route network structure from point-to-point to hub-and-spoke to provide basic aviation services,to serve for the country’s powerful civil aviation strategy and to pursue the high-quality development of the industry.To accomplish the “transformation from large air country to powerful air country” proposed by CAAC,it is extremely important to study how to build a rational hub-and-spoke route network and optimize the corresponding fleet configuration,so as to improve the mutual adaptability between the route network and the fleet and to take advantage of the scale economy of hub-and-spoke network operation.The existing literature has achieved fruitful results on hub-and-spoke network design and fleet planning researches.However,most literatures separated hub network design and fleet planning,both of which are strategic decisions.So the decision schemes may have negative impacts on tactical decisions(matching aircraft types and routes),causing the decision schemes suboptimal.Therefore,it is necessary to integrate aircraft types and routes matching with hub-and-spoke network designing and fleet planning.Under the optimization target of minimizing airlines’ total operation cost and combined with specific application scenarios,two integrated models of hub-and-spoke network and fleet joint planning are built for single and multiple allocation hub-and-spoke network structure respectively.An integrated planning model of non-strict hub-and-spoke network and fleet is also developed with the goal of airlines’ total operating cost and service objects’ time cost.Then three heuristic algorithms are designed to solve the specific problem.The validity of the models and algorithms is verified by instances and sensitivity analysis.This paper mainly studies the integrated planning and decision-making of hub-and-spoke network and fleet from three aspects as follows.(1)Integrated planning problem of single allocation hub-and-spoke network and fleet considering operation costTraditional methods are disconnected from each other in solving the two kinds of decisions for route network design and required matching transportation capacity,and do not consider key resource constraints.To compensate these deficiencies,the representation method for variable and allocating fixed cost of aircraft types and routes to replace the economies of scale is first derived.Then,fully considering the resource constraints such as the maximum flight frequency on each route and the available flight time of the fleet,based on the single allocation hub-and-spoke network structure and on the premise of meeting the transportation demand of each city pair(origin and destination,O&D),a mathematical model for the integrated planning of the single allocation hub-and-spoke network and the fleet is developed with the goal of minimizing the total operation cost of the airline.Meanwhile,a variable neighborhood search algorithm and an optimal allocation algorithm of route capacity are designed to solve the model.The results of instance analysis show that:(1)The integrated planning mathematical model of the single allocation hub-and-spoke network and fleet is more consistent with the actual operation than existing models,while the designed algorithm is efficient and feasible.(2)The available flight time of the fleet and the maximum flight frequency of each route are airlines’ key resource elements.Only by considering their constraints in the hub-and-spoke network design and fleet planning,the planning schemes can better meet with the needs of future actual operations.(2)Integrated planning problem of multiple allocation hub-and-spoke network and fleet considering operation costMinimizing the unit operation cost is considered as the matching criterion of aircraft types and routes by the existing integrated planning literatures.Against these deficiencies,the demand matching window of aircraft types and routes is constructed based on the relationship between aircraft capacity and route transportation demand.Based on the multiple allocation hub-and-spoke network structure,to meet the transportation demand of each O&D,the demand matching window is incorporated into the hub-and-spoke network design and fleet planning decisions as the criterion of aircraft types and routes matching.With the goal of minimizing the total operating cost of airlines,an integrated planning mathematical model of multiple allocation hub-and-spoke network and fleet is built.The genetic algorithm and Floyd-Warshall algorithm considering the variable cost are developed to solve the model.The results of instance analysis show that:(1)The integrated planning model considering demand matching window is more practical,and the solution algorithm designed is efficient and feasible.(2)The demand matching window is one of the key factors affecting hub-and-spoke network design and fleet planning,while the utilization rate of fleet with specific type of aircraft determines the fleet configuration,which has relatively less impact on the design scheme of hub-and-spoke network.(3)Integrated planning problem of non-strict hub-and-spoke network and fleet considering operation and time costThe air service objects chooss the direct transportation or transit transportation route after comprehensively considering the cost and time when traveling.Therefore,when designing hub-and-spoke network,it is necessary to relax its basic limit and allow direct transportation between non-hub cities.First,the calculation method of time cost for service objects is established based on the non-strict hub-and-spoke network structure.Then,on the premise of meeting the transportation demand of each O&D,the integrated planning model of non-strict hub-and-spoke network and fleet is developed with the goal of minimizing the sum of airlines’ total operating cost and service objects’ time cost.The tabu search algorithm and the shortest path algorithm considering the time cost are designed to solve the model.The results of instance analysis show that:(1)The integrated planning model considering the cost of operation and time is reliable,and the algorithm designed is efficient and feasible.(2)The more airlines pay attention to the time cost of service objects,the more direct routes should be opened,and the operation mode of high-frequency and small capacity aircraft should be adopted.(3)The hub-and-spoke network structure is suitable for serving the O&D market with low transport demand,while the direct transport is suitable for serving the O&D market with high passenger transport demand.