Changes in travel mode use over the life course with partner interactions in couple households

The paper links the mobility biography approach with studies on intra-household interactions between partners in travel. It does so by developing a multi-group path model – a structural equation model without latent variables – of changes in car use over time as a function of changes in activity and trip patterns, path dependency (baseline car use), life course changes, and the respective respondent's partner's car use, activity and trip patterns. In terms of life course changes, the paper accounts for (gradual, rather than abrupt) changes in paid and unpaid worktime, and the birth of a first or higher-order (i.e. second or further) child. The model further categorises respondents by gender. It focuses on couples who share one car. A model for multi-car households is estimated for comparison. The results show multiple interactions between two partners at the baseline as well as over time. The effects of the birth of a child are less clear than expected. Generally, they suggest that increases in driving are primarily an outcome of higher-order births, especially in one-car households. Policy conclusions are (1) that it may be overly optimistic to assume that the birth of a child can be utilised as a 'window of opportunity' to reduce driving, and (2) that social interactions between partners should be taken into account in policy concepts.