2E-VRP-SBS instances
Description
In considering route optimization at a series of express stages from pickup to delivery via the intercity linehaul, we introduce the two-echelon vehicle routing problem with satellite bi-synchronization (2E-VRP-SBS) from the perspective of modeling the routing problems of two-echelon networks. The 2E-VRP-SBS involves the inter-satellite linehaul on the first echelon, and the pickups from senders to origin satellites (i.e., satellites for cargo collection) and deliveries from destination satellites (i.e., satellites for cargo deliveries) to receivers on the second echelon. The 2E-VRP-SBS integrates satellite bi-synchronization constraints, multiple vehicles, and time window constraints on the two-echelon network and aims to find cost-minimizing routes for various types of trucks. Small-scale instances. Considering the computing abilities of CPLEX 12.4 indicated by some computational trials, there are one depot, three origin satellites, and three destination satellites on the first echelon. The number of senders or receivers served by an origin satellite or a destination satellite is assumed to be the same, and the number of senders or receivers served by a satellite is 5, 6, 7, 8, or 9. Each small-scale instance is denoted by num_os-num_ds-num_gc-sn, where num_os or num_ds denotes the number of origin satellites or destination satellites, num_gc is the number of senders or receivers served by a satellite, sn is the instance sequence for the same num_os, num_ds, and num_gc, and sn is 1, 2, 3, 4, 5, 6, 7, 8, or 9. We designed the large-scale instances by referring to data provided by a logistics company in China. Referring to the locations of 17 distribution-centers (DCs), which are located in 17 prefecture-level cities in Shandong province, we designed the nodes on the first echelon as follows. First, it is assumed that each DC can be used as the depot, i.e., the depot location is the same as one of the DC locations. The large-scale instances are distinguished by the location of the depot. Second, there are 17 origin satellites with different locations, and the location of an origin satellite is the same as the location of a DC. Third, there are 17 destination satellites with different locations. The location of a destination satellite is the same as the location of a DC, and the location of an origin satellite should not be the same as the location of a destination satellite, if there are inter-satellite linehaul demand between the origin satellite and the destination satellite. Generally speaking, we designed 17 large-scale instances that are distinguished by the location of the depot. The number of senders or receivers served by an origin satellite or a destination satellite is assumed to be the same. The number of senders or receivers served by a satellite is 120. The sending-receiving relationships between senders served by an origin satellite and receivers served by destination satellites are randomly generated.