Scope Designing good transport policies, including but not limited to planning infrastructure development, requires insight into the likely development of the demand for transport. In the past decades, the aggregate demand for passenger travel has long developed in line with per capita GDP and population growth, but there are strong signs that this close connection is weakening in advanced economies. In particular, car travel volumes in some countries are no longer growing or have declined despite continued growth in GDP. It is important to understand why this is so. Is the phenomenon transitory or is it permanent? Are changes in relative prices the explanation, or is it that higher GDP no longer translates into more disposable income for many households? Have attitudes towards car travel changed, perhaps in combination with increased availability of non-car transport modes, or are socio-demographic factors (e.g. ageing, urbanisation) responsible?
All explanations are plausible and probably a combination of them explains the aggregate trend. Furthermore, the relative importance of different factors may differ among countries and between places within countries (e.g. urban and rural regions), as a quick glance at available evidence indeed suggests. Separating out the various driving factors is important for making good projections of travel demand as well as for other facets of transport policy (emissions, congestion management, etc.). This holds for the economies where the demand for car travel appears to be levelling off, but also for developing economies as they may be confronted with similar changes at lower levels of incomes (e.g. because of more rapid urbanisation and different policy incentives). The aim of the roundtable is to further the emerging understanding of the drivers of changes in passenger travel and to discuss policy implications.