Though different forms of public–private partnerships exist, in the organizational structure of most forms a public and a private project organization can be derived, resulting in two collaborating project organizations. The literature on project management however mostly considers one project organization. The literature on public–private partnerships considers the public part of the organization mostly as ‘the client’. This research focuses on the relationships between public and private organizations: the two collaborating project organizations, the relationship with their parent organizations, and with external actors. Exploratory interviews in three cases uncovered five mechanisms leading to tensions between project partners: ambiguity, conflict of interest, triangular relationships, unclear purpose and organizational context.

Purpose - The authors argue that public project managers do not consider the iron triangle (cost, quality and schedule) primary important in measuring the success of their projects. To investigate which success criteria are important to public project managers, the authors interviewed 26 Dutch project managers who are employed by the government and who are responsible for managing infrastructural projects. The paper aims to discuss these issues. Design/methodology/approach - In this research the Q-methodology is applied. Q-methodology helps to find for correlations between subjects across a sample of variables. Q-factor analysis reduces the individual viewpoints down to a few factors. A factor can be seen as the mathematical representation of an "average" perspective shared by a group of people. Findings - Findings are based on the individual rankings of 19 success criteria; the authors distinguished three common perspectives: the holistic and cooperative leader, the socially engaged, ambiguous manager and the executor of a top-down assignment. In none of the perspectives the iron triangle criteria formed the top three to measure project success. Research limitations/implications - The research results may have a national character. The way project success is perceived by public project managers may be culture dependent. For this the authors expand the research to other countries in the near future. Practical implications - This paper contributes to the understanding of the public project manager by their private collaboration partners, like consultants, engineers and contractors. This will help them to understand their client and contribute to better collaboration in projects. Originality/value - This paper shows that the difference in work attitude and value frame in the public sector leads to a specific view on project success.

Public and private project managers contribute to the success of Large Infrastructure Projects. Considering the public client, so far researchers have been looking at him in a passive role with respect to project success. The focus of this exploratory research is what public project managers who are actively involved in the project, consider project success. Using Q-methodology, we identify four viewpoints in the respondent group, consisting of managers from five North-Western European countries and the specific success criteria accompanying these viewpoints. Within each viewpoint, the managers have the same vision on the ranking of project success criteria. Next to the conventional project manager, we distinguish the product driven manager, the parent oriented manager and the manager with a stakeholder focus. In Large Infrastructure Projects, where public and private partners collaborate, awareness of these different perspectives will help to understand the motives of the public project manager.