This paper addresses the problem of transmission planning in interconnected power systems under the uncertainty of future generation parks and fast varying marginal production costs. The decision maker has to consider many different aspects during the definition of different transmission planning strategies that sometimes might even be contradicting. Major contributions are the incorporation of energy policy measurements in the evaluation process of candidate transmission plans and the inclusion of short-and long-term uncertainties. The proposed methodology, so-called C-TRAP, is based on a semi-dynamic heuristic approach that solves the social welfare maximization problem for several discrete steps considering different preferences for energy policy and transmission network reinforcements. The flexibility provided through the heuristic analysis is very important for decision makers in the new uncertain environment in power systems. (c) 2013 Elsevier Ltd. All rights reserved.