I belong to a two-adult, one-car household. Yet even if I didn’t, my husband and I would be more likely to decide to move from a 0-car or multi-car household to a one-car household than most other two-adult households because we have just had a baby. This is according to some new research by the University of the West of England, University of Essex and Department for Transport called the Life Transitions and Travel Behaviour project (funded by ESRC).

It is common sense that major life events cause people to reconsider a range of lifestyle choices and behaviours. The Life Transitions project studies this on a statistically significant basis using data from the Understanding Society survey and British Household Panel Survey, which together track the relationships, employment, attitudes and health of tens of thousands of individuals over time. The analysis focused on commuting choices and car ownership changes in households encompassing 32,000 people over 18 months. The research also took into account contextual factors such as whether the households were in urban or rural areas, the age and gender of individuals in the households and environmental attitudes.

Most of their conclusions match common sense expectations – an individual who gains their driving license is likely to want to own a car. The number of cars in a household correlates with the number of adults and therefore households that gain or lose an adult through decisions to cohabit or separate are likely to gain or lose vehicles too. Likewise, if switching/relocating employment or moving home increases commuting distance to over two miles, people are more likely to switch to commuting by car than if their situation had remained unchanged, whilst if distances are reduced to under three miles, they are more likely to switch to non-car and active modes of travel. The research also confirms that context such as proximity to amenities and availability of public transport contribute to both car ownership and commuting mode decisions.

All these conclusions and more (see project website: http://travelbehaviour.com/) are valuable to practicing transport planners, who are expected to play a major role in promoting travel behaviour change for a variety of reasons: reducing congestion in an urban area, improving the health of a local population, or meeting climate change targets. The Department for Transport recommends that transport planners use its Behavioural Insights Toolkit and Enabling Behavioural Change guidance to support funding bids and implement Government policy locally.

Apps, advertisements, challenges, competitions, confidence building, championing, crowd-sourcing, information, incentives, loyalty schemes, nudges, social marketing, media campaigning, personalised travel planning – the tools available are many and multiplying. Having strong, scientific evidence to support how the use of these tools is targeted is essential to optimise their effectiveness.

The research also revealed a few surprises that may suggest alternative targeting. The one that particularly caught my eye was why households having a child should seek to become a one-car household. In fact, in the stable population (those not experiencing a life event), children being present in households made it more likely that the household would have one car instead of none or two. This is despite the fact that having a child makes an individual more likely to commute by car if staying in employment.

Does this mean that those who are relinquishing a car after having a child are doing so because they are no longer in employment and decide to become full-time parents? Do they seek to be one-car households because disposable income is lower if the mother is on maternity leave and then due to the costs of the child? What is the difference in effect between having a first child and subsequent children? Does the age of the children matter? Or the age gap (e.g. if wider, then it is more likely that the household will have a number of years when the children will need to go in different directions to nursery, primary school, secondary school)? These questions were beyond the scope of the project and may result in sample sets too small to be significant if the same methodology is used as for the main project. However, they are questions I can relate to personally, and indicate the path to further research that has been launched by the Life Transitions project.