This volume is the result of an international collaboration, which started with a conference at Smadalaro Gfrrd in Sweden. The workshop was supported by the National Science Foundation of the USA (INT-9215114) and by the Swedish National Road Administration, the Swedish Council for Building Research, the Swedish Transport and Communications Research Board and the Swedish Council for Planning and Coordination of Research. This support is gratefully acknow ledged. The collaboration started as a bilateral u.S.-Swedish endeavour but was soon widened to other scholars in Europe, Asia, Australia and South-America. Network Infrastructure and the Urban Environment is a policy area of growing importance. Sustainable cities and sustainable transport systems are necessary for attaining a sustainable development. The research and policy field, represented in this volume, comprises a number of challenging contrasts: - the contrast between infrastructure investments, mobility and environmental sustainability; - the contrast between policy contexts, modelling traditions and available decision support systems in various parts of the world; - the contrast between available best practice methods and the majority of models applied in planning; the contrast between static models of cross-sectionary equilibria and dynamic models of disequilibrium adjustments; and the contrast between state-of-the-art operationalland-use/transport models and new demands for land-use/transportlenvironment models due to changing policy contexts. Bridging some of these gaps constitutes important research tasks, that are discussed in the twenty-two chapters of this book. A number of emerging research directions are identified in the introduction and summary chapter.