Integrating public transport in sustainable last-mile delivery: Column generation approaches
研究了协调三阶段最后一公里配送系统的问题，利用公共交通闲置运力将包裹运入市中心，提出列生成算法，在24个算例中找到16个新最优解。
We tackle the problem of coordinating a three-echelon last-mile delivery system. In the first echelon, trucks transport parcels from distribution centres outside the city to public transport stops. In the second echelon, the parcels move on public transport and reach the city centre. In the third echelon, zero-emission vehicles pick up the parcels at public transport stops and deliver them to customers. We introduce two extended formulations for this problem. The first has two exponential sets of variables, while the second has one. We propose column generation algorithms and compare several methods to solve the pricing problems on specially constructed graphs. We also devise dual bounds, which we can compute even when the graphs are so large that not a single pricing round completes within the time limit. Compared to previous formulations, our models find 16 new best known solutions out of an existing dataset of 24 instances from the literature. • We optimise a three-echelon last-mile delivery system. • Spare capacity on public transport is used to bring parcels into the city centre. • We propose column-generation-based methods for an extended formulation. • We find 16 new best known solutions for an instance set from the literature.