[en] This comprehensive final report for the Swiss Federal Office of Energy (SFOE) reviews work done on the development of new power transmission planning tools for restructured power networks. These are needed in order to face the challenges that arise due to economic, environmental and social issues. The integration of transmission, generation and energy policy planning in order to support a common strategy with respect to sustainable electricity networks is discussed. In the first phase of the project the main focus was placed on the definition of criteria and inputs that are most likely to affect sustainable transmission expansion plans. Models, concepts, and methods developed in order to study the impact of the internalisation of external costs in power production are examined. To consider external costs in the planning process, a concurrent software tool has been implemented that is capable of studying possible development scenarios. The report examines a concept that has been developed to identify congested transmission lines or corridors and evaluates the dependencies between the various market participants. The paper includes a set of three appendices that include a paper on the 28^th USAEE North American conference, an abstract from Powertech 2009 and an SFOE report from July 2008.