A hybrid urban delivery system with robots

Cities are now restricting access for conventional delivery technologies in some areas, requiring businesses to adopt more flexible distribution systems to complete their deliveries. We present a two-echelon hybrid truck-based robot delivery system for last-mile logistics operations. Robots can navigate through truck no-go areas such as pedestrian zones and college campuses, while trucks can travel through less restricted areas. The hybrid delivery model allows the distribution system to automatically select the better distribution strategy, thereby improving distribution efficiency. We present a mixed-integer linear program to model the proposed system. We also offer valid inequalities to strengthen the formulation and a large neighborhood search-based algorithm with innovative adaptive methods and multiple operators to solve medium and large-scale instances efficiently. Computational experiments are conducted to evaluate how our proposed model performs. Sensitivity analysis experiments considering truck no-go areas of different sizes and area access time windows are performed and reveal managerial insights. We suggest setting up appropriate time windows for some truck no-go areas to reduce the burden of logistics companies in increasing distribution routes due to access restrictions.