The European Union needs harmonised guidelines to improve the appraisal of large-scale infrastructure dedicated to the Trans-European Networks (TEN); in order to contribute to such guidelines, EU-funded EVA-TREN analyses ex-ante studies and projects outcomes at European level. EVA-TREN’s First Experts’ Workshop has gathered experts of large-scale infrastructure planning and operation of the domain of transport and energy. Investigation of their practices highlights the following issues: first, the appraisal frameworks EU countries apply for transport and energy projects differ considerably in scope, sophistication, methodology and parameter values; second, the EU Member States share only a small part of all research results; and third, transnational projects are still problematic within the Union. As a result, cost overruns appear in the majority of projects. Investigation of the EU Cohesion Fund programme reveals that one project in four costs more than 20% above budget, while only one in five stands below + 10%. The main problems are modifications to the project (30%) and delays (25%); inadequate cost estimates and technical reasons are quoted in only 20% of overcosts. Sustainability does not explicitly appear in the appraisal process, even though it is repeatedly quoted as a central aspect of the decision whether an infrastructure should be built or not. Transport and energy projects essentially differ in finance and elasticity: most infrastructure investments in the transport sector require public funding, whereas those in the energy sector usually do not need any; the situation is similar for operation at regional level. In the transport sector, provision of new road capacities induces additional transport demand, while provision of new electricity lines has very little effect on demand. In terms of methodology, the quality of evaluations would benefit from increased transparency and from improved feed-back, as would provide for instance peer review of ex-ante assessment and more systematic ex-post evaluations. Combination of methods may as well contribute to better appraisal. Two approaches based on Cost Benefit Analysis (CBA) look promising: Netherlands’ Overview Effects Infrastructure (OEI) and Japan’s combination of CBA and Multi-Criteria Analysis (MCA). OEI puts emphasis on the exploration of the problem and on the survey of effects, while Japan’s procedure relies on MCA for ranking projects amongst those that score sufficiently well in CBA outcome and it allows other projects to be reassessed considering intangible values, which gives them a second chance. Experts consider macroeconomic models very bad at providing data that are meaningful for CBA; in the case spatial dynamics is tackled at national level only, and therefore produces data that are not detailed enough for assessments at regional or local level, the missing data should be generated through regional/local scenarios. In practice, the match between evaluation results and project outcomes would be improved if authorities take actions on four topics: to start with, they should use masterplans; then, they should only select mature projects - for which they request measurable and quantified goals, results and impacts; third, they should establish a clear managerial body; and fourth, they should provide assistance on administrative and financial matters as well as methodological support on assessment procedure.