We describe a framework for running large-scale multi-agent simulations of travel behaviour. The framework represents each traveller as an individual ‘agent’ that makes independent decisions about its desired use of the transportation system during a typical day. An agent keeps a record of its decisions in a ‘plan’. A plan contains the agent’s schedule of activities it wants to perform during the day, including times and locations, along with the travel modes and routes it intends to utilise to travel between activities.