Operational strategies for single-stage crossdocks.

摘要

Because of the growing importance of hub-and-spoke operations in the trucking industry, crossdocking has become an important and effective tool to transfer freight. Companies like Wal-Mart, Costco and Home Depot are using this kind of facility in their logistics operations. In these crossdocks, efficiently operating them, thereby reducing unnecessary waiting and staging congestion for freight and workers is an important issue for managers.;This dissertation uses real-time information about the contents of inbound and outbound trailers and the locations of pallets to schedule unloading for waiting trailers or assign destinations for unloading pallets: we choose a waiting trailer that will need the least time for its pallets and existing pallets; and we may assign an alternate destination for a pallet if its primary destination is expected to encounter congestion. Two dynamic trailer scheduling and four alternate destination strategies are proposed and compared with baseline scenarios.;Our simulation results suggest that: (1) Our strategies are effective. The two time-based trailer scheduling algorithms can save cycle times as much as 64%, 57% and 30% in the 4-to-4, 4-to-8 and 8-to-8 crossdock scenarios, respectively; the four alternate destination strategies can save cycle times as much as 34% in the 8-to-8 staging crossdock scenarios. In addition, these strategies can raise throughputs for crossdocks. These effects should result in noticeable improvements in supply chain networks, including shorter transportation lead-times, more reliable on-time deliveries and lower inventory costs. (2) In our alternate destination strategies, even if a destination-change results in extra time for value-added services for freight, the strategies are still worth adopting. (3) The combination models of our trailer scheduling algorithms and alternate destination strategies work better than solely implementing an alternate destination strategy when trailer arrivals are dense. (4) A higher flexibility in choosing alternate destinations can bring higher performance for crossdocks.