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ELA - Robust consolidation of tactical wagon routes in railway freight traffic (BMBF)

Background:

Single wagonload traffic is a particular production form in railway freight traffic. Small groups of wagons have to be transported but their size does not justify direct transport. There, wagons from different relations, i.e. origin-destination pairs, are decoupled, sorted and consolidated in shunting and reclassification yards. Our research project dealt with the question for the optimal sequence of yards for each wagon.

Approach: 

Firstly the central issues were analyzed in cooperation with our project partner Deutsche Bahn Mobility Logistics. In particular, the volatility of demands in wagonload traffic have been identified as an important planning aspect. Therefore, we designed a mathematical flow models which finds a cost efficient solution for multiple demand scenarios. The resulting problem is NP-complete and very large-scaled for real-world applications. Considering the problem structure, we developed a Branch-and-Price-and-Cut approach which outperformed the commercial standard solvers for the problem. Nevertheless, it was impossible to solve real-world instances. A new matheuristic approach, i.e. a combination of metaheuristic and exact optimization elements, turned out to be the most efficient way to solve the problem.

Results:

The matheuristic method was implemented into a software prototype at our project partner Deutsche Bahn. Even for large instances, it is able to find feasible solutions with an optimality gap of less than 10% in 12 hours.

Contact: Prof. Dr.-Ing. Uwe Clausen

 

Bundesministerium für Wirtschaft und Technologie logo_tuev_rheinland Schmidt-Gevelsberg GmbH
Log!n BHS Spedition und Logistik GmbH logo_algorithm_engineering