Ett informationsblad från matematiska institutionen vid Linköpings universitet. Material till Lite Mat lämnas till Maud Lindström litemat@mai.liu.se senast torsdagar kl 12.00.

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***LITE MAT***

Ett informationsblad från matematiska institutionen vid Linköpings universitet

v24 2001

Licentiat-seminarium

Torsdagen den 14 juni kl 13.15 presenterar Nima Golbaharan sin licentiatavhandling

An Application of Optimization to the Snow Removal Problem - A Column Generation Approach

Diskutant är doktor Niklas Khol, Senior Consultant, Carmer Consulting AB.

Abstract: The cost of the snow removal operation is considerably affected by the routing of the snowploughs. The difficulty of routing increases, when operational regulations on the routing stipulated by Swedish National Road Administration, must be taken into consideration. In general, the problem of routing of snowploughs has different characteristics depending on whether the routing is performed after the snowfall or during the snowfall. Furthermore, the operational regulations that require satisfying a time window on each treated road segment, give rise to a more complex routing problem. The computational complexity is increased when the time windows are wide. In this thesis, we focus on developing and implementing a solution method for the routing of snowploughs after snowfall with wide time windows. Ploughing of each road segment is to be performed within a specified time window for that road segment. We solve the problem by an optimization approach based on the Dantzig-Wolfe decomposition method. The routes are generated according to a column generation procedure. The master problem is a linear problem and the subproblems are Constraint Shortest Path Problems. An integer solution to the overall problem is obtained by using two different approaches. The first approach is based on the use of branch and bound procedure and the second one on the use of a greedy search procedure. Both approaches result in a heuristic solution. The solution method is applied to the operation district of Eskilstuna.

This work has been financed by the Swedish Transport and Communication Research Board, KFB, and the Swedish National Road Administration, VV.

Lokal: BL32, hus B

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