Contributed Session Thu.3.MA 042

Thursday, 15:15 - 16:45 h, Room: MA 042

Cluster 13: Logistics, traffic, and transportation [...]

Real-world applications


Chair: Kaj Holmberg



Thursday, 15:15 - 15:40 h, Room: MA 042, Talk 1

Kaj Holmberg
Planning and routing in networks: Urban snow removal


We study the problem of planning service tasks in street networks, and use snow removal as a generic problem. Snow removal is (sometimes) an important problem. Drastic weather changes might become more frequent in the future, which indicates a need to handle unusual situations. Computerized optimization based tools for planning will be a help.
The goal is to find good a plan: When should each task be done, which vehicle should do the task and how should the vehicle travel between tasks. Different vehicles have different capabilities and tasks may have precedence requirements. The objective function may include finishing times, costs and environmental aspects.
The problem is too difficult to be solved by standard methods, but there are several usable structures in the problem, such as the Chinese postman problem, the rural postman problem, the asymmetric traveling salesman problem as well as scheduling with precedence constraints. We discuss solution methods containing several different heuristic parts building up and improving the solutions, using decomposition frameworks. Some preliminary conclusions from a real life example are mentioned.



Thursday, 15:45 - 16:10 h, Room: MA 042, Talk 2

Rodrigo Moretti Branchini
Fleet deployment optimization model for tramp and liner shipping

Coauthor: Vinícius A. Armentano


We present a generic mixed integer mathematical programming model to tackle operational and tactical planning problems faced by liner and tramp shipping companies in maritime logistics. The liner shipping company pickups and delivers client cargoes, e.g., containers, along a pre-established route analogous to the hop-in and hop-off of passengers in a bus line. A tramp shipping company does not have a predefined route to follow, the route is constructed and executed as new demands arrive. Although the relevance of the types of decisions for each operation is different, for example daily routing decisions are more important to tramp than to liner companies, both operations share similar structure, such as the goal of profit maximization while fulfilling established contracts agreements, and may have part of the decision making process modeled and solved using a generic MIP formulation. The decisions addressed by the model are the definition of fleet size and mix (e.g., which vessels to charter in/out or lay-up), the evaluation of spot voyages contracts and and the determination of vessel routes and schedules. The model was implemented with CPLEX and computational results are reported.


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