סמינר מחלקתי - יובל אלבר

Recently, cities have begun to incorporate battery-powered electric buses in their bus fleets. For example, Dan, the largest bus operator in the greater Tel Aviv area, declared its plan to acquire 5 electric buses this year, after a 2-year long pilot with one bus. The transition to electric buses is motivated by the technological evolution of high-capacity batteries for electric vehicles and the growing public awareness to the shortfalls of the currently prevailing diesel technology. Due to the risk involved in adapting new technologies and because the operational lifespan of diesel buses is 12-15 years, it is likely that the transition to electric buses will occur gradually. Therefore, for an extended period, there will be a need to plan the transit system operation of fleets that contains at least two types of buses. These two types have significantly different operational cost structures and range limitations. In particular, the operational range of electric buses is limited and thus, charging or battery-swapping operations should be included in their daily schedule. This study extends the classic bus scheduling models and solution methods to the more complex problem of scheduling mixed fleets. We formulate the model as an integer program and devise a math-heuristic that can solve larger instances. These solutions method are tested and compared using instances that are based actual time-tables of Dan in Tel Aviv and Metro-Dan in Beer-Sheva.