定期航線貨櫃存量管理與空櫃調度之研究

Container Inventory and Repositioning Management for Liner Shipping Service Routes

定期航運面臨市場競爭激烈，運價調升空間不大，如何有效分配艙位與 管理貨櫃資源，節省營運成本，為各航商所面臨的重要問題。然而航 商攬貨常以最大化艙位利用率為目標，依據各靠港代理行攬貨能力分配艙 位，業績表現亦多以艙位達成率來衡量，較少考量貨載之邊際貢獻與櫃流不 平衡產生的空櫃滯留儲存費與調櫃成本。此外，航商不斷的擴大船隊、增加 航線，以及投入大型貨櫃船到歐美等主要航線，造成艙位過剩、運價低迷， 而亞洲新興國家製造業快速成長，大量的消費性貨品從亞洲港口輸出歐美國 家，然而從歐美國家輸出到亞洲國家的貨量卻少很多，造成定期航運櫃流不 平衡，航商必須從多櫃區調度空櫃到缺櫃區，維持空櫃在一定的存量，支援 運務之需求，導致航商空櫃調度成本大幅增加。目前貨櫃調度作業多半仰賴 專業人員之經驗判斷，較缺少系統化的程序作為調櫃決策依據，因此本研究 參考櫃調相關文獻以及訪談公司櫃調人員，提出貨櫃存量與空櫃調度流程， 引用存貨控制模式，推導櫃調前置時間、空櫃存量與再調櫃點；並應用線性 規劃建立之櫃調模式求算最佳調櫃量，並以國內某航商之一條越太平洋美西 航線作簡例進行數值分析。研究結果發現貨櫃調度前置時間為缺櫃港開始進 行空櫃調度到空櫃調回到港的時間，是影響缺櫃港空櫃存量與再調櫃點最重要的因素；貨櫃安全存量除了受貨櫃調度前置時間影響外，另外會受到貨運需求的不確定性，以及航商所期望的顧客服務水準影響。

As liner shipping companies have been facing fierce market competition, freight rate increase is hard to achieve and most liner companies cannot make reasonable profits. Additionally, most liner shipping companies have been increasing their fleet and service routes, and they deploy large-size containerships to Asia/Europe and Asia/America routes. These approaches resulted in overcapacity, low capacity utilization and low freight rate. Moreover, the number of shipments from Asian ports to Europe and America far outnumbered the shipments from Europe and America to Asia. These trade imbalances resulted in container flow imbalances. Consequently, liner shipping companies have to spend substantial costs in repositioning empty containers between excess container zones and demanding container zones and to maintain safety stock empty containers to support the needs of customer services for those empty zones. This research formulates an empty container inventory control model to derive container repositioning lead time, safe stock and repositioning point. Additionally, linear programing is utilized to formulate an optimal empty container repositioning model to minimize repositioning costs. A numerical case study of a transpacific service route is implemented to verify the feasibility of the proposed models. The results show that the key factors influencing empty container inventory and repositioning points are repositioning lead time, uncertainties of shipment demand and service level of liner shipping companies.