基于货物时间价值的空铁联运转运枢纽选址优化

高效合理的联运网络是空铁联运快递服务产品创新的重要支撑。本文在考虑货物时间价值的基础上，以空铁联运转运枢纽的位置以及运输方式选择为决策变量，构建以综合成本最低为目标的空铁联运转运枢纽选址模型，并设计变邻域遗传算法进行模型求解。以截至2019年开通高铁并设有机场的200个地级城市为例，采用复杂网络和优劣解距离法结合的方法选取空铁联运转运枢纽的备选城市，验证模型和算法的实用性及有效性。结果表明，运输时间限制和折扣系数是影响空铁联运网络综合成本的重要因素。随着运输时间限制的增加以及折扣系数的降低，空铁联运网络综合成本分别降低了15%和11%。空铁联运转运枢纽的空间布局主要受运输时间限制的影响。运输时间限制较低时，空铁联运转运枢纽布局以东北地区和西部地区为主，以提高快递运输的时效性。运输时间限制较高时，空铁联运转运枢纽布局向中东部地区转移，为经济服务趋势明显。空铁联运网络最优枢纽数量则受运输时间限制和折扣系数的综合影响，但运输时间限制对于最优枢纽数量的影响更为显著。合理布局空铁联运转运枢纽和提升空铁联运规模效益是提高空铁联运服务时效性和竞争力的重要途径。

Optimization of Air-rail Transshipment Hub Location Based on Time Value of Goods

An efficient and reasonable intermodal transport network is an important support for the innovation of air-rail intermodal express service products. In this paper, considering the time value of goods, an air-rail intermodal transfer hub location model is constructed, which takes the location of the air-rail intermodal transfer hub and the choice of transportation mode as decision variables with the objective of the lowest comprehensive cost. A variable neighborhood genetic algorithm is designed to solve the model. Using 200 prefecture-level cities with high-speed rail and airports as of 2019, alternative cities for air-rail transit hubs were selected using a combination of complex networks and superiordisadvantage solution distance methods. The practicality and effectiveness of the model and algorithm are verified. The results show that the transportation time limit and discount factor are important factors affecting the comprehensive cost of the air-rail intermodal transportation network. With the increase in transportation time limit and the decrease in the discount factor, the integrated cost of the air-rail intermodal transportation network is reduced by 15% and 11% respectively. The spatial layout of air- rail intermodal transfer hubs is mainly influenced by transport time constraints. When the transportation time limit is low, the layout of air-rail intermodal transfer hubs is mainly in the northeast and western regions to improve the timeliness of express transportation. When the transport time limit is high, the layout of air-rail transit hubs shifts to the central and eastern regions to serve the economy. The optimal number of hubs in the airrail intermodal transport network is influenced by the combination of the transport time limit and discount factor, but the transport time limit has a more significant impact on the optimal number of hubs. It is an important way to improve the timeliness and competitiveness of air-rail intermodal transport services to reasonably arrange air-rail intermodal transport hubs and improve the scale efficiency of air-rail intermodal transport.