Over the past 10 to 15 years, the growth of passenger vehicle travel volumes has decelerated in several high-income economies and, in some, growth has stopped or turned negative. Drawing from work presented to and discussions at the ITF Round Table on Long-run Trends in Travel Demand, held in November 2012, this paper presents evidence on known causes of this change in growth rates and discusses knowledge gaps, hypothetical explanations and policy implications.

In many advanced economies, car use per head, and sometimes total car traffic, has shown low growth. In some countries (and especially cities) it has declined. In a few countries, there have been similar studies of the distance travelled by all modes added together, which has shown a similar trend though with some doubts about how international air travel should be handled. It is generally agreed that the trends in the last few years must be influenced by world economic problems, but some of the possible changes in trends seem to go back ten or twenty years, with signs detectable even further back.

Although there are differences of emphasis, the statistical facts of a reduction in historic growth, low growth or stability at national level, and reductions in specific locations, especially some larger urban areas, seem broadly agreed by most analyses. This evidence is sometimes ignored, but it is not contested.

There is great interest in the appearance of some common features in many countries, notably including changes in the propensity to get driving licences among young adults (especially teenage men), an apparent weakening of the association between income and mobility, a greater influence of public transport, walking and cycling to economic prosperity in some of the most successful cities, and the development of e-commerce, telecommuting and social networks.

There are currently differences in judgement on how influential these factors are, and on whether the observed trends are temporary or reflect structural shifts which could be long-lived. These differences especially focus on the relative importance of economic issues (particularly prices and incomes) and wider social and cultural changes, such as mobile internet access, demographic, gender, attitudinal and cultural trends, the effects of transport policies and the possibilities of deeper concepts of “saturation” of mobility when further increases bring little extra benefit. There is at the moment no strongly-established common view about future growth in car use to the extent that was taken for granted in earlier decades.

The paper discusses research needs, and some emerging issues for future transport policies, including the appraisal of large-scale transport infrastructure projects, service provision, pricing, the allocation of risk and initiatives to reduce car dependence, in the context where forecasts are problematic and contested.

After decades of increases, the growth in driving in the United States is levelling off, and dropping on a per capita basis. These shifts have enormous implications for public policy in the US and abroad, as evidence shows that this phenomenon is generally reflected in developed counties around the world with mature transportation systems. Yet while there is little doubt that the sputtering US economy has a major impact, emerging research suggests the changes in driving habits also result from a long-term structural change, reflective of a host of shifts in demographics, culture, technology, as well as settlement patterns in US metropolitan areas. But whether due to a momentary blip or long-term structural changes, the changes have important implications for public policy. For example, US roadways are arguably safer and less congested. However, the resulting declines in gasoline consumption also result in less revenue collected from gasoline taxes and fewer resources for all modes, including public transport. The key is for policymakers to understand these new developments and their impacts on transportation finance, the environment, and general economic development. This paper explores those macro forces through an analysis of driving trends, a review of existing literature and a discussion of what is likely behind these trends, as well as implications for public policy.

A mobility analysis, carried out in early 2011 by the Netherlands Institute for Transport Policy Analysis, showed that, following the remarkable growth in the 1980s and 1990s, the overall national mobility of the population in the Netherlands has not increased since 2005. This particularly appears to apply to car use. Except for the credit crisis around 2008-09, the reasons for this development remained unclear at the time. Based on further analyses of the developments in mobility over the last ten years and some findings from other countries, the following four hypotheses related to the apparent stabilisation of car use were formulated and investigated in further research:

- The mobility system has started to show signs of “saturation”; for instance, in car ownership levels, a reduced need for mobility to perform activities, less need to increase activity opportunities due to improvements in the mobility system, structural frictions in housing and labour markets, etc.;

- The broad implementation of the (mobile) Internet in society (e-working, e-shopping, e-commerce, use of social networks) is leading to a reduction in physical (car) mobility;

- The mobility of young adults is declining as a result of changes in socio-economic, spatial and cultural factors;

- National mobility is being taken over by international mobility.

In the first part of our contribution, a detailed description of the developments in mobility between 2000 and 2010 is presented, with emphasis on specific trends for various user categories (by travel mode, by age group, by gender). This part can be seen as a description of recent developments in mobility growth.

In the second part we present the findings of our recent research related to the four hypotheses. As some of these findings differ somewhat from research results in other western European countries, we will also focus on these differences and their possible explanations. We conclude this part of the contribution by formulating some possible implications from our findings for transport policymaking.