In this paper, a model of territorial impact assessment, both theoretical and operational, is presented and applied to the assessment of Trans European Networks policies. Methods and Results A methodology of TIA is proposed starting from a theoretical definition of territorial cohesion, intended as the territorial dimension of sustainability. Its three dimensions namely territorial efficiency, quality and identity and sub-dimensions become the criteria and sub-criteria of a multicriteria impact model, working both with quantitative and qualitative variables. The potential impact of a policy is made truly territorial through a double regionalised coefficient of desirability (territorial utility function) and vulnerability of single regions to each typology of impact. An operational interactive simulation package (SIP) is built and applied to the impact of priority TEN policies on NUTS 3 European regions. Conclusions The methodology proposed proves theoretically sound and methodologically correct: it allows a flexible and interactive definition of some political coefficients (the weights of the different criteria, the variation field of the standardised and scaled variables, the form of the utility functions) and encompasses the relevant dimensions of territorial sustainability both traditional and relatively new ones, like those connected to territorial identity. The results of its application to TENs policy prove consistent and worth further work on the statistical side.