Minimizing Departure Time for Outgoing Trucks in a Crossdock

論文發表人: 王建富 (加州大學爾灣分校運輸科學博士班)

 

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越庫碼頭(Crossdock)在供應鍊營運中扮演著重要的角色。由於在供應鍊環節中某些活動對於減少運輸前置時間的要求提高,例如及時物料供給、客製化生產以及中途併貨等策略,使得縮短貨品在越庫碼頭的處理時間顯得亦形重要。在本研究中,我們針對等待入庫卸貨的貨車加以排程,以使得貨品在等待出庫的貨車之等候時間最少,亦即使其停留在越庫碼頭的時間最短。我們採用了動態模擬的模式來比較三種排程策略:先到先服務(first-come-first-served) 、look-ahead 以及 leave-early。我們發現當採用leave-early策略及在配備有四個卸貨碼頭與四個出貨碼頭的越庫碼頭時,相較於其他兩種策略,我們的策略能為貨物節省最高達百分之十二等候時間或者最高達百分之四的整體轉運時間。

 

Crossdocks play important roles in supply chain operations. Due to the need to decrease transportation leadtime to coordinate with other supply chain activities such as just-in-time, make-to-order or merge-in-transit strategies, the importance of shortening total processing time at crossdocks has increased. In this research, we schedule waiting inbound trucks in such a way to allow for the early departure of outgoing trucks.  This minimizes the time freight spends in a crossdock. We use a dynamic simulation model to compare the performance of first-come-first-served, look-ahead and leave-early policies under different truck inter-arrival times and crossdock layouts. From our simulation results, we find that our leave-early algorithm can save up to 12% on freight wait time in outgoing trucks and 4% on total time relative to the other policies under a 4 receiving doors and 4 shipping doors layout. In addition we suggest guidelines for choosing scheduling algorithms in different situations.