The creation of an efficient public transport system increasingly requires collaboration between independent organizations. Institutional reforms in Europe have created governance situations where collaboration between organizations is a critical issue, and examples include the integration of transport and land-use planning and the planning of large public transport projects. The organizational context of public transport, with several formal, discrete organizations that need to collaborate, raises questions about how functioning collaborations can be accomplished. This paper examines how to create functioning collaboration between organizations in the public transport sector. We depart from a theory of collaboration as a stepwise trust-building process, and we present results from a comparative case study of collaboration in two Swedish public transport projects. The results show some of the prerequisites that must be in place in order for the collaboration to work, but also the boundaries of what collaborative approaches can bring about. Conditions such as honest, open, and inclusive dialog between stakeholders and resources in the form of finance, knowledge, mandate, and leadership are important. While there is no guarantee that this will lead to differences in interests being resolved, the results indicate that it improves the chances of finding compromises that all of the involved stakeholders can accept, especially if favorable conditions for collaboration are established at an early stage of the planning process. Building on these findings, we suggest some practical recommendations for improving collaboration in future public transport projects. These practical recommendations are aimed at improving the handling of unavoidable conflicts in collaboration in a constructive way.