The environmental research institutes behind this proposal offer a unique interdisciplinary research competence in addressing the linkages between societal drivers, environmental change, impacts and policies in a common analytical framework, i.e. the enhanced causal chain for the relations between transport and environment. Sustainable transport is chosen as a common, and increasingly crucial, environmental research area. Transport produces the more persistent, and resistant, of the environmental problems. It also brings about a broad range of problems: both global and local emissions; health and ecological impacts; land take and landscape changes. Therefore, transport is often the source of substantial environmental policy goal conflicts. Focusing on the environmental trade-offs highlights the dilemmas of sustainable transport. It serves as a methodological crucial case, testing the thesis of sustainable transport under its most difficult conditions, when a solution has controversial effects. Overcoming these conflicts means handling difficulties in political, administrative and academic priorities and concerns, and pave the way for more robust solutions also under the more likely, more beneficial conditions.