Synchronization of regional public transport systems

Transferring from one vehicle to another is generally inevitable in public transportation. In urban areas this often includes changing between vehicles operated by different companies. It is well known that good transfer possibilities increase the attractiveness of public transportation. Since this is an important goal, in the present paper we study the synchronization of timetables between different operators with an individual timetable planning process. The synchronization task is a very complicated problem due to the large amount of transfer locations and possibilities and the fact that they are interrelated network-wide. Our main contributions are a model to evaluate transfer quality locally and globally and an interactive optimization approach that allows an integration of the power of mathematical optimization algorithms with the expertise of the planners. We demonstrate our approach by highlighting some results achieved for the public transportation network of the city of Kaiserslautern, situated in south-western Germany.