As the complexity of urban planning increases by the discovery of new issues and new dynamics, it appears that the “role of the planner as the technical expert just supporting the political decision makers has been progressively substituted by the awareness of the wicked nature of planning problems” (Balducci and Mäntysalo 2013) and that “the notion of value-neutral expertise is no longer widely accepted” (Innes 1998). In this framework, an attempt to show the necessity for participation in public transportation planning for sustainable development derived to a proposal for defining the framework of participation, based on theories of communication, and a proposal for a series of important aspects to be taken into consideration for designing and assessing a participation framework, based on additional theories of participation processes. The study of two case studies in Switzerland and in Japan is then analysed with this framework and the results are discussed in a comparison, putting into perspective the specificities of each case with the aim of bringing a better insight about participation framework and processes. The extent to which are influenced public transportation in each case is also assessed, highlighting the need to focus on an issue specific to this transportation mode in order to make the study of participation process in this field relevant. Finally, a set of recommendation is proposed, based on the theory from the first part and the points highlighted in the second part. EPFL