定期航運艙位超賣模式之研究

A SLOT ALLOCATION MODEL WITH OVERBOOKING FOR LINER SHIPPING

定期航運業常因顧客臨時取消貨櫃運送或是減少艙位需求，造成空艙之損失。艙位是不可儲存之商品，船公司可運用收益管理之超賣策略，求取適當的超賣數量，將艙位做更有效的分配利用而提升利潤。再者，由於國際貨櫃流量之不平衡，船公司必須做好空櫃調度，以降低因貨櫃流量不平衡所帶來之龐大成本負擔。本文以銷售艙位之數量為著眼點，探討定期航運艙位超賣下單一航線之艙位分配模式，在考量各港口有其獨立之離散型顧客到達率情形下，提供船公司一套系統化的方式，藉以決定單一航次之艙位銷售數量以及空櫃調度，求取最大化利潤。經由案例顯示具超賣策略之模型，可帶給船公司更高之期望利潤，且其影響隨著顧客到達率之不確定性增高而更為顯著。

The liner shipping industry often suffers from no-shows and cancelations that make some container slots empty for a voyage. Container slots are perishable assets and can not be stored for the next voyage. A liner shipping company can enhance the slot utilization and reduce unused capacity by properly adopting the overbooking strategy, an important element of revenue management. On the other hand, due to the unbalanced container flow caused by the international trade pattern, a liner shipping company has to reposition the containers efficiently and effectively to satisfy the container need while trimming the reposition cost. In this paper, we discuss slot allocation on a single route by considering slot overbooking. By assuming a discrete customer show-up rate at each port, we propose a systematic approach to determine the amount to sell and the way to reposition empty containers so as to maximize the profit of the liner shipping company. We use a numerical example to show that the proposed overbooking model can increase the expected profit of the company. Moreover, the influence of adopting overbooking becomes more pronounced when the uncertainty of the customer show-up rate increases.