We introduce a two-echelon urban delivery problem with second-level unmanned vehicles. This problem typically applies for delivering parcels or other small commodities to pedestrianized areas such as campuses or residential clusters. To model the proposed vehicle routing problem, we introduce a mixed-integer program. We further propose construction heuristics and a hybrid metaheuristic approach with backtracking for solving larger instances. A sensitivity analysis for vehicle speed combinations reveals that increasing small autonomous vehicle (SAV) speeds has only very limited effects on cost. We therefore recommend to keep SAV speeds rather low because of a more pedestrian friendly environment in practical implementations.

我们介绍了使用二级无人驾驶车辆的两级城市配送问题。此问题通常适用于将包裹或其他小商品运送到行人专用区，例如校园或住宅群。为了对提出的车辆路径问题建模，我们引入了一个混合整数程序。我们进一步提出了构造启发式方法和具有回溯功能的混合元启发式方法来解决较大的实例。车速组合的灵敏度分析表明，提高小型自动驾驶汽车（SAV）的速度对成本的影响非常有限。因此，我们建议将SAV的速度保持在较低水平，因为在实际实施中会更加人行友好。