Despite high expectations, in The Netherlands the formation of public-private partnerships (PPPs) in the field of transport infrastructure is stagnating. This article addresses the question of why this is the case. On the basis of a comparative analysis of 9 case studies concerning the building of partnerships, 3 patterns are identified. The first is the successful formation of partnerships resulting in enriched projects. The second pattern is that of early interaction resulting in ambitious proposals for which there is no support. The third pattern shows ineffective market consultations followed by unilateral public planning, leading to stagnating contract negotiations.

These patterns are coherent and are caused by a number of generic factors. An important explanation for stagnation is the lack of interaction. As a result, public and private parties will fail to reach a common understanding, will be unable to contribute to the enrichment of the project content and will fail to develop mutual trust. If parties engage in early interaction, the lack of embeddedness of their efforts may result in an uncritical piling up of ambitions and an absence of the capability to realize trade-offs and generate support. These explanations are related to the absence of conscious and systematic attempts to manage and arrange interaction processes aimed at the formation of PPPs. On the basis of these findings the author formulates a number of suggestions to improve the quality and effectiveness of these processes.