The impacts of household structure on the individual stochastic travel and out of-home activity time budgets

The amount of time individuals and households spend in travelling and in out-of-door-activities can be seen as a result of complex daily interactions between household members, influenced by opportunities and constraints which vary from day to day. Extending the deterministic concept of travel time budget to a stochastic term, and applying a Stochastic Frontier Model to a dataset from the 2004 UK National Travel Survey, this study examines the hidden stochastic limit and the variations of the individual and household travel time and out-of-home activity duration– concepts associated with travel time budget. The results show that most individuals may not have reached the limit of their ability to travel and may still be able to spend further time in travel activities. The analysis of the model outcomes and distribution tests show that among a range of employment statuses, only full-time workers’ out-of-home time expenditure has reached its limit. Also observed is the effect of having children in the household: children reduce the flexibility of hidden constraints of adult household members’ out-of-home time, thus reducing their ability to be further engaged with out-of-home activities. Even when out-of-home trips are taken into account in the analysis, the model shows that the dependent children’s in-home responsibility reduces the ability of an individual to travel to and to be engaged with out-of-home activities. This study also suggests that, compared with the individual travel time spent, the individual out-of-home time expenditure may perform as a better budget indicator in drawing the constraints of individual space-time prisms.