具時窗多趟次車輛途程問題與委託零擔貨運服務之模式

A Mathematical Model for a Multiple Trip Vehicle Routing Problem with Time Window and Outsider Carrier Selection

物流為航運管理重要的一環，如何將貨物由配送中心運送給顧客，是一項很重要的實務問題，因為運輸成本在物流各項成本中所占之比例很高。在實際生活中，由於需求具有波動與不確定性，當顧客需求超過業者所擁有之車隊容量時，業者必須考慮以員工加班運送或將過剩的需求委託零擔貨運運送。本研究以單一配送中心為研究對象，主要研究目的為在配送中心擁有不同車種與面臨需求超載之情境下，建構一整合具時窗多趟次車輛途程與委託零擔貨運服務之整數規劃模式，協助物流管理者解決問題。研究結果顯示，藉由本研究中所建構之整數規劃模式可提供物流管理者對車輛指派更具調度彈性，降低營運成本，增加公司利潤。 Physical distribution plays an important role in the shipping industry. Considering transportation costs amount for a fifth or even a quarter of the average sales dollars, the delivery of goods from a depot to local customers is an important and practical problem for logistics managers. In reality, we are facing the fluctuation of demand. When the total demand is greater than the whole capacity of owned trucks, logistics managers may consider adopting a multi-trip strategy or using an outsider carrier. In this study, logistics managers must route a fixed number of trucks with different capacities from a single depot to customers with certain demand while trucks can operate multi trips with time window constraints or logistics managers make a selection of less-than-truckload carriers. The main objective of this study is to develop mathematical model to help logistics managers solving the problem. The results show that the proposed integer programming model can provide more flexible vehicle scheduling for logistics managers, lower operating costs and increase profits for a company.