Travel Time Budget – Decomposition of the Worldwide Mean

The paper is concerned with the travel activity and more specifically the urban travel time during a day. This individual mean travel time budget (TTB) has been hypothesised by Zahavi (1980) to be a constant amount of time close to 1 hour per day. This TTB seems to be stable between different cities and between different time periods. Under the TTB stability hypothesis, travel time-savings are totally reinvested in transport. This reinvestment mechanism could then explain the urban sprawl, and give to the increasing speeds all the responsibilities of the “urban transport diseases”. However, the TTB stability seems to be valid at the world aggregate level only. The paper proposes to explore finer scales of observation of the TTB: from the aggregate to the desaggregate levels of observation. First, a worldwide comparison of the mean TTB of 100 cities is produced. Second a hazard based model for the individual TTB of the French city of Lyon is constructed. Hence, two opposite urban models appear at the aggregate level: an extensive urban model of which development is based on extensive consumption of space and time resources, and an intensive urban model restricting its spatial and temporal extension. At the desaggregate level, the analysis identifies the relationships between the individual TTB and the socio-economic variables and the mobility and activities attributes. Finally, the model seems to indicate that the traditional hypothesis of the minimisation of the temporal costs of travel is unsuitable to model the behaviour of the whole urban population.