Multiobjective Approach to Creating Bus Timetables with Multiple Vehicle Types

In times of climate change and scarce resources, it is essential to reduce emissions and to use fuel as economically as possible. The transportation sector alone accounts for 44% of the energy use in New Zealand, with only about one-quarter of that amount being used by the transportation industry for transporting goods. Therefore, an attractive public transport service and prudent use of its vehicles can help make travel more economical, thus saving resources and reducing carbon dioxide emissions. How to make public bus services more attractive is demonstrated with two simultaneous objectives: minimizing the expected passenger waiting time and minimizing the discrepancy from a desired occupancy level on the vehicles. The first objective is intended to improve the service and attract more users, and the second objective is intended to ensure economical operation. A network-based procedure is used to create timetables with multiple vehicle types to solve this multiobjective problem. The method is applied to a case study in Auckland, New Zealand, and results in a savings of more than 43% of passenger waiting time while attaining an acceptable passenger load on all vehicles.