A distributed constraint-based search architecture for bus timetabling and duty assignment

In order to manage the daily operation of a bus company, different types of scheduling must be performed on a regular basis: bus timetabling, duty assignment, bus assignment, rostering, driver assignment, etc. Due to problem complexity and limitations of available computer technologies, these scheduling activities are often performed by separate software systems. Even within a single type of scheduling, the schedule for each route is generated independently of each other. This mode of isolated scheduling leads to inefficient schedules since interrelated constraints are not considered and resources cannot be shared among routes. This paper documents research that explores how a distributed constraint-based scheduling architecture might shed some light on this integration problem. Our current software prototype integrates the scheduling tasks of bus timetable generation with duty assignment and permits bus and bus driver resources to be shared among routes. This approach guarantees that the resulting timetable satisfies both service requirements as well as bus driver labour constraints.