The future framework of the transport system is closely linked to the general energy supply of the future. The relatively cheap availability of petroleum oil has allowed great expansion of the transport system over the past hundred years. This relationship between energy supply and vehicle technology and the characteristics of the transport system is typified by the internal combustion engines that power much of the transport system. However, circumstances are changing. There is an increasing concern about the environmental consequences of the fuel technology used. Just as important are the concerns over the future availability of the fuel required. The recurrent crises and even wars in some areas where oil and gas is produced and the instability of political systems in other fuel producing areas only add to this. Driven by these issues, a wide range of new or improved fuel technologies are being proposed and developed, each with its issues over the wider consequences of its adoption. The implications of the various futures are best considered by investigating a series of scenarios reflecting a range of 'best' estimates of future conditions in the energy, transport, economic and social fields. This explains the background behind the STEPS project. The overall aim of STEPS is to develop, compare and assess possible scenarios for the transport system and energy supply of the future and supports both the overall FP6 programme objective and the specific future needs of the transport energy sector. In doing this it takes into account effects such as: - autonomy and security of energy supply; - effects on the environment; - economic, technical and industrial viability; - interactions between transport and land use. The results of STEPs constitute a valuable synthesis of the main findings on trends and policy scenarios and their predicted effects. STEPs results serve as a basis for the development of a view on future policy and give insight into research requirements in the area of transport and energy scenarios. The main findings on trends are: - The long-term future of energy supply for transport appears difficult, and the situation has become significantly more critical even during the short project period of STEPs. - Today a growing majority of experts believe that because of a combination of scarcity in cheap oil, increased global energy demand and greater supply disruptions provoked by geopolitical dependence of Europe, fuel prices will continue to rise in the medium and long term. Indeed, mostly due to the emerging economies in Asia (in particular China and India), energy demand is rising significantly more than oil production and oil refining capacity, making disruptions in energy supply a major and increasing concern. The share of worldwide energy demand and energy market stress that these markets bring along with their expansion is overwhelming. The growth of mobility and transport systems in most Asian countries has progressed at a different speed; India and China had a slow start but have now surpassed Western regions in their economic growth rates, which is directly reflected in their transport demand, mobility growth, and increased energy demand. - All trends in economic activity, goods transport and personal travel, point towards longer distances and, despite energy efficiency gains, to more energy consumption. This reflects a pattern shared by most industrialised countries which have developed their economy and lifestyles firmly rooted in the promise of cheap energy supply. A trend towards an ever-increasing intensity of freight transportation is observed. In the passenger transport sector a trend for increased mobility coupled with faster and more flexible realization of mobility needs and an increase in the use of private automobiles contunies. This is noticeable in the increasing traffic flows, the modal split, high car dependency, etc. These trends are unsustainable vis-à-vis the trends of declining energy supply, increased supply disruption risks, higher energy costs and the growing risks of climate change. - All efforts to decouple economic growth and energy consumption and to reduce greenhouse gas emissions have, with a few local exceptions, failed and are insufficient to meet the more demanding post-Kyoto targets. The main findings on policies are: - Demand management policies making road transport slower or more expensive (push measures) are more efficient in reducing transport fuel consumption than policies promoting more sustainable transport modes, such as walking/cycling or public transport (pull measures). Integrated strategies combining push and pull demand management policies, technology development policies and land use policies are more successful than isolated individual policies. The efficiency depends on the level of change of both push and pull measures, and availability of alternatives. - Technology development policies making vehicles more energy-efficient or promoting alternative propulsion systems are successful in reducing fuel consumption per km, but tend to result in longer distances travelled by both passengers and freight unless the higher costs of new technologies are taken into account. - All policies using dominant push measures resulting in lower fuel consumption for transport have negative effects on accessibility and hence economic activity. Public transport fare reductions (pull measures) would have good impacts on accessibility and lower fuel consumption.