Editorial Understanding behavioural change: An international perspective on sustainable travel behaviours and their motivations Selected papers from the Travel Behaviour Track in the Demand Topic Area of the 12th World Conference on Transport Research In an era of international fiscal austerity and global environ- mental threats there is a growing urgency for improved under- standing of how to encourage more sustainable travel behaviours worldwide, particularly in and around cities. By 2050, the world population is expected to increase from 7.0 billion to 9.3 billion. At the same time, the population living in urban areas is projected to grow from 3.6 billion to 6.3 billion. Thus, the urban areas of the world are expected to absorb all the population growth expected over the next four decades, while at the same time drawing in some of the rural population (United Nations, 2012). Problems related to urban mobility have, for decades, been a major concern for citizens and policy makers. Despite some attempts for restraint, cars continue to be the most popular mode of travel in developed countries given their door-to-door flexibility, comfort, privacy, and multi-functionality. In developing countries the increase in car use and car ownership has been rapidly catching up with the devel- oped world, especially in Latin America, India and China (Dargay and Gately, 2010). Consequently, traffic congestion on urban roads has become a common scene all over the world. Surface transport is an essential service in any modern society. Goods transportation ensures that products can be shipped from factories to markets. Passenger transport, both private and public, allows people to visit each other, go to work or school, and participate in a myriad of economic and social activities. An efficient transport system is often a major precondition for economic growth, competi- tiveness and employment. Transport is therefore fundamental to human society and economy and insuring proper mobility is vital for the competitiveness of markets and well-being of citizens. However, transport is also a main contributor to environmental problems such as deteriorating air-quality, noise and, not less important, CO 2 emissions. In the 2011 white paper on transport policy the European Commission highlighted that urban transport accounts for 40% of CO 2 emissions of road transport and approximately 70% of other pollu- tants from transport (European Commission, 2011). Increasing use of cars for everyday mobility has also been associated with health degradation in western countries (Schnohr et al., 2006). Evidently, there is need for better public policies to contend with the wide- spread dependency on the car in everyday life. As a generally available public good, transport is limited by its throughput capacity. Hence, historically, the focus of transport policy in developed countries was on transportation supply and demand management, mostly aimed at mitigating traffic conges- tion (Shiftan and Golani, 2005) and improving flow within existing capacities. Despite some areas of success (e.g. in amending planning codes for new developments and improving public transport) these policies have only managed to slow the rate of car trip and distance travelled increase, but not completely reverse these trends. People drive not just to work, but to shopping, to school, to sports, to visit family and friends, and so on, while the available evidence suggests that a notable share of driving is by choice (Handy et al., 2005). Compact development, higher parking fees and fuel costs have made car use less attractive, particularly in Europe, though still relatively wide spread. There are some who claim that in recent years we are beginning to see, in the West, a start of a possible reverse trend in car-use known as ‘peak-car’, related to economic hardships, changes in residence locations and rapid proliferation of informa- tion and communication technologies like high-speed internet and smart mobile phones (Puentes and Tomer, 2009). However, this would still need to be seen over a longer time horizon before it can be empirically verified. It has also become apparent that travel behaviours are strongly associated with personal choice, social lifestyles and urban contexts. A result of complex interactions between attitudes, perceptions, information, and knowledge, interpersonal relationships and social norms (Steg, 2005), and external physical circumstances related to urban form (Schwanen and Mokhtarian, 2005; Mokhtarian and Cao, 2008; Shiftan and Barlach, 2002). This makes motivating more sustainable travel behaviours challenging. Thus, it is clear that for policies to be successful in reducing car use, these interactions must be better understood and accounted for in policy formulation. As these studies have been conducted almost entirely in developed countries, there is still a wide gap in the state-of-the-art regarding the trends and behaviours in developing countries. The World Conference on Transport Research (WCTR) aims to provide a venue for presenting transport research from various regions and countries, with particular emphasis on presenting research conducted in developing countries. In this ensemble of eight selected papers from the Activity and Transport Demand Analysis track of the 12th WCTR hosted in Lisbon in July, 2010, we present an international collage of papers on understanding sustainable travel behaviour motivations from different geogra- phical contexts and social backgrounds. A broad range of policies and behavioural aspects are covered, including push and pull measures, as well as soft policies; policies targeting the general population compared to children and adolescents; different trip types such as service trips and recreation trips; and various travel modes, including cycling. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/tranpol Transport Policy 0967-070X/$ - see front matter & 2013 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.tranpol.2013.02.003 Transport Policy 26 (2013) 1–3