The Spatial Pattern Analysis And Distribution Optimization Of Air Cargo Transportation Network

Along with the upgrade of industrial structure and rapid e-commerce development in China,more and more short life-cycle or time-sensitive products rely on air transport.Hence,air cargo transportation as a business becomes a new growth point in China civil aviation transport industry.This paper considers China civil aviation freight transport network as study objects,spatial statistical analysis and multi-objective optimization model are adopted to study the evolution of spatial pattern of China air cargo transportation and airport accessibility during 2001 to 2013,and optimize air cargo transportation network layout.The result will not only guide resource allocation of air cargo transportation from the supply-side but also provide important theory support to China air cargo transportation industry development and airport layout optimizationFirst,based on SDE and Spatial Gini index,this paper analyzes the spatial pattern evolution characteristic of air cargo transportation in China,the result shows:(1)The spatial pattern of air cargo transportation is consistent with economic distribution,mainly concentrating in Shanghai and Hangzhou-the core of Yangtze River Delta,Guangzhou and Shenzhen-the core of Pearl River Delta,Beijing and Tianjin-the core of Beijing and Tianjin District,as well as developed areas in western China(Chengdu and Chongqing),China flight transport center is moving to the northwest inland region from the southeast coastal areas.(2)Four combination airports(Beijing/Tianjin,Shanghai/Hangzhou,Guangzhou/Shenzhen and Chengdu/Chongqing)replace Beijing,Shanghai and Guangzhou and become four highly concentrated regional air cargo transportation combination hubs,Air freight network is switches from coexistence hybrid network(point-to-point structure,hub-and-spoke hub structure)to hub-and-spoke network.(3)The air freight at airports and flight segments tends to disperse,and its volume on hub airports and main routes reduces slowly year on year,Regional airports and branch flight segments undertake more and more air cargo.(4)Between four combined hubs air cargo transportation main corridors are established,the 30%of total air freight volume was concentrated on those corridors.Second,this paper employs weighted sum of annual available freight tonnage from one airport to others as a measuring index to analyze the spatial-temporal change of air-side freight transport accessibility of China civil aviation airport.The result shows:(1)Air-side freight transport accessibility of the airport increases year by year.The absolute variance of the accessibility between airports becomes larger and the relative variance becomes smaller.In addition,more than 80%airports are below average value of the airport accessibility.(2)Beijing,Shanghai,Guangzhou and Shenzhen airports take the first four positions in the ranking of air-side freight transport accessibility of the airport.(3)Air-side freight transport accessibility of the airport comes down exponentially.(4)Air-side freight transport accessibility of the airport gap between east and west airports narrows down.(5)Air-side freight transport accessibility of the airport in seven region shows increasing trend and in west grows faster than east and north.Final,aiming to maximize the network accessibility and utilization,this paper simulates a multi-objective bi-level programming model.In the upper model,cargo aircraft flights are distributed to the segments to maximize the network accessibility and utilization.In lower model,air cargo transportation route and mode are determined to minimize the total transport cost.The model is solved by NSGA-II algorithm and the trade-offs between the objectives are reflected by Pareto optimal solutions.In this paper,the distribution of air cargo transportation network is studied by taking 20 airports in China in 2013 as an example.The results show:(1)A quarter of cargo aircraft flights is distributed to the segments between Beijing,Shanghai,Guangzhou and Shenzhen,which are considered as hub airports in the network.(2)When the decision maker prefers to the network accessibility,more cargo aircraft flights should be distributed to the segments between the hub airports.On the contrary,cargo aircraft flights should be evenly distributed to the segments if the average network utilization is preferred.(3)If cargo aircraft flights distribution tends to disperse on the segments,the network accessibility will decrease,but the network utilization will increase in the optimized schemas.(4)Reducing the total number of cargo aircraft flights will decrease the network accessibility.On the other hand,increasing the total number of cargo aircraft flights will decrease the network utilization.