The core problem of the economic organization of society is that of facing and dealing with uncertainty. In particular, it is the level of uncertainty that the parties involved in Public-Private Partnership (PPP) projects face and their need for flexibility that most clearly distinguishes PPP projects from conventional ones.

Typically, a project starts with very high level of uncertainty at inception, which is reduced until all the information required for the project is embodied in the constructed product. PPP projects usually bear the feature of much prolonged uncertainty due to their decades of lifecycle and the difficulty in foreseeing future uncertainties, especially those inherent in later stages.

Uncertainty may be categorized into environmental and behavioral ones. The former bears important relevance in that behavioral uncertainties would not pose contractual problems if transactions were free from exogenous environmental uncertainties.

In this paper, risk factors that can cause a given risk were seen as uncertainties associated with this risk because risk factors better describe the risk-related situations that can be individually assessed with a limited quantity of vague information. An innovative way based on fuzzy sets theory is used in this paper to assess the level of environmental uncertainties.

This may be further used in other decision-making processes in PPP projects, such as the process of risk analysis and the process of determining risk allocation strategy.