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08. Branching Strategies to Improve Regularity of Crew Schedules in Ex-Urban Public Transit Steinzen, Ingmar Suhl, Leena Kliewer, Natalia We discuss timetables in ex-urban bus traffic that consist of many trips serviced every day together with some exceptions that do not repeat daily. Traditional optimization methods for vehicle and crew scheduling in such cases usually produce schedules that contain irregularities which are not desirable especially from the point of view of the bus drivers. We propose a solution method which improves regularity while partially integrating the vehicle and crew scheduling problems. The approach includes two phases: first we solve the LP relaxation of a set partitioning formulation, using column generation together with Lagrangean relaxation techniques. In a second phase we generate integer solutions using a new combination of local branching and various versions of follow-on branching. Numerical tests with artificial and real instances show that regularity can be improved significantly with no or just a minor increase of costs. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Ingmar Steinzen and Leena Suhl and Natalia Kliewer 2007 Is Part Of OASIcs, Volume 7, 7th Workshop on Algorithmic Approaches for Transportation Modeling, Optimization, and Systems (ATMOS'07) (2007) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/OASIcs.ATMOS.2007.1167 urn:nbn:de:0030-drops-11674 https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2007.1167 eng https://creativecommons.org/licenses/by-nc-nd/3.0/legalcode