6.1 Conclusion
Scheduling algorithms are used at sea ports all over the world to make sure that terminal operators can handle the loading and discharging of container vessels as quickly as possible.
The algorithm of [Hen09] combines the Berth Allocation Problem and the Yard Allocation Problem. This algorithm is adapted to fit the situation at the MSC Home Terminal in Antwerp. Terminal specific constraints on the berthing of the vessels have been modeled to match the restriction of the terminal. In the Yard Allocation Problem an extra means of transport is added, the multi trailer. This device can take multiple containers at once and transport them between two fixed interchange zones. To see the effects the use of the multi trailer on the performance of the algorithm, a sensitivity analysis has been clone. The effect of the following parameters has been investigated.
We tried to estimate the value of the multi trailer costs by tuning the parameters in such a way that the behavior of the model represents the situation at MSC Home Terminal. When these multi trailer costs are known, a sensitivity analysis is performed to investigate how the model reacts on changes in the other parameters. In this analysis, only one parameter is changed each time.
• Number of multi trailers
The number of multi trailers affects the multi trailer capacity. Adding multi trailers up to a number of 4 will decrease the objective function value. Adding even more multi trailers will have no effect on the objective function value. This means that 4 multi trailers with each 4 trailers will be able to all the necessary work.
• N umber of trailers per multi trailer
The number of trailers per multi trailer not only affects the multi trailer capacity, but also affects the multi trailer costs. When a multi trailer can transport more containers in one run, the multi trailer costs per container will decline. In this analysis, a number of 12 trailers are needed to meet all multi trailer transport demand.
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44 Chapter 6. Conclusions and recommendations
• Location of the interchange zones
Due to the specific characteristics of MSC Home Terminal, only one interchange zone can be moved. The interchange zone position at zone 2 has the lowest objective function value. This position is located almost at the far left end of the terminal.
When we move it from this position to the middle of the terminal, we see that the multi trailer is used less, and the objective function rises. From this analysis we see that the current interchange zone position at MSC Home Terminal gives a relatively high objective function value in the model.
6.2 Recommendations
Based on the findings 111 this report, some recommendations for further research can be made.
• In the original model, all costs were expressed in terms of straddle carrier distances.
With the introduction of the multi trailer in the model, different sorts of costs, like maintenance come to play a role. This is why it is hard to compare the straddle carrier costs to the multi trailer costs. In this research the multi trailer costs are fixed, and the model is tuned in such a way that the behavior of the model represents the situation at MSC Home Terminal. In order to be able to make a realistic comparison between the two different means of transport, research could be done to find the factors t.hat influence the choice when to use a multi trailer or not. With this knowledge, a more sophisticated multi trailer cost factor could be created.
• The specific layout of MSC Home Terminal can have a big impact on the behavior of the model. Research might point out for which terminal layout and dimensions the multi trailer would perform best.
• In this research the use of a multi trailer at MSC Home Terminal is investigated. The multi trailer is chosen as an alternative means of transport to straddle carriers. This is not the only alternative though, and research could focus on alternative means of transport in the yard.
Bibliography
[Gua04] Y. Guan and R .K. Cheung. The berth allocation problern: Models and solutions methods. OR Spectrum, 26:7592, 2004.
[Hen09] M.P.M. Hendriks. Multi-step optimization of logistics networks strategie, tactical, and operational decisions. Phd thesis, 2009.
[Henll] M.P.M. Hendriks, E. Lefeber, and J.T. Udding. Simultaneous berth allocation and yard planning at tactical level. submitted to OR Spectrum, 2011.
[Ima08] A. Imai, H. Chia Chen, E. Nishimura, and S. Papdimitriou. The simultaneous berth and quay crane allocation problem. Transportation research part E, pages 900-920, 2008.
[Sta08] R. Stahlbock and S. Voss. Operations research at container terminals: a literature update. OR Spectrum, pages 1-52, 2008.
[Ste04] D. Steenken, S. Voss, and R. Stahlbock. Container terminal operation and oper-ations research - a classification and literature review. OR Spectrum, pages 3-49, 2004.
[Vis03] I. Vis and R. de Koster. Transshipment of containers at a container terminal: An overview. European Journal of Operational Research, pages 1-16, 2003.
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46 Bibliography