Evaluating the sustainability risk level of public-private partnership (PPP) projects can reduce project risk incidents and achieve the sustainable development of the organization. However, the existing studies about PPP projects risk management mainly focus on exploring the impact of financial and revenue risks but ignore the sustainability risks, causing the concept of "sustainability" to be missing while evaluating the risk level of PPP projects. To evaluate the sustainability risk level and

more »

... achieve the most important objective of providing a reference for the public and private sectors when making decisions on PPP project management, this paper constructs a factor system of sustainability risk of PPP projects based on an extensive literature review and develops a mathematical model based on the methods of fuzzy comprehensive evaluation model (FCEM) and failure mode, effects and criticality analysis (FMECA) for evaluating the sustainability risk level of PPP projects. In addition, this paper conducts computational experiment based on a questionnaire survey to verify the effectiveness and feasibility of this proposed model. The results suggest that this model is reasonable for evaluating the sustainability risk level of PPP projects. To our knowledge, this paper is the first study to evaluate the sustainability risk of PPP projects, which would not only enrich the theories of project risk management, but also serve as a reference for the public and private sectors for the sustainable planning and development. the costs of constructing and operating public hospitals and other health care facilities and delivering services by constrained national budgets [11] . Hoejmose et al. proposed that responsible supply chain management can help protect a firm's corporate reputation by shielding it from negative media attention and consumer boycotts [12] . However, many studies explored the role of organization and ecosystem in complex PPP projects [13] [14] [15] . Even though there are so many studies on PPP projects, unfortunately, little attention has been given to sustainability risk of PPP projects. Here, sustainability risk is the combination of likelihood and consequences of events which affect the achievement of organization's sustainable development. It is related to the concepts of sustainable development and the "triple bottom line" [16] , which emphasizes "the development should meet the needs of the present world without compromising the ability of the future generations to meet their own needs" [17] . Sustainability risk has been brought into many areas, and numerous studies have been conducted to discuss its connotations, applications and mechanisms. Among them, Touboulic and Walker [18] investigated theoretical perspectives in sustainable supply chain management and contributed to understanding the current state in the field of PPP and its future development. Cucuzzella [19] presented a series of design projects to illustrate the difference in thinking and outcomes when sustainability is thought of in varying temporal and spatial perspectives. Harclerode et al. [20] developed a foundational framework to define and integrate the sustainability and risk management objectives in the life cycle of complex project towards a more sustainable state. In the area of PPP project management, the common perception of sustainability risk evaluation involves economy, society, resources, and environment aspects, and aims at monitoring changes of PPP projects, adjusting strategies so that a balance among economy, society, resources, and environment can be found. However, there is no recipe for reaching this balance [21, 22] . Furthermore, complex arrangements and incomplete contracting in PPP projects have led to increased risks of unsustainability, for both public and private partners [23, 24] . Effective sustainability risk evaluation of PPP projects is therefore challenging and demanding. At the same time, the accuracy of sustainability risk evaluation is crucial for PPP as a whole [25] . Risk evaluation of PPP projects is fundamentally different from that of traditional projects, where traditional projects emphasize the temporary and disposable nature of which risk evaluation is limited to the processes of design and implementation. In PPP projects, investors place special emphasis on the sustainability of projects and are entitled to reducing investments or terminating projects if PPP fails to achieve sustainability standards. Accordingly, one of the most important drivers for value-for-money is sustainability risk evaluation, which means the sustainability risk of a PPP project can be evaluated, prevented, and controlled during the implementation process [26] . As a result, lower-risk and higher-quality PPP projects may be implemented relative to conventional methods. This work is intended to reduce project risk incidents and achieve the sustainable development of the organization by accurately evaluating the sustainability risk level of PPP projects and achieving the most important objective of providing a reference for the public and private sectors when making decisions on PPP project management. The rest of this paper is organized as follows. Section 2 analyzes the main influencing sustainability risk factors of PPP projects, by classifying these factors into five categories: culture and society, cost and economy, ecology and environment, project and organization, politics and policy, via an extensive literature review, and then this paper builds a factor system of sustainability risk of PPP projects. In Section 3, a fuzzy comprehensive evaluation model for assessing the sustainability risk level of PPP projects, based on FCEM and FMECA, is proposed, which provides a holistic view focused on reflecting the sustainability risk level factors of PPP projects by evaluating the sustainability risk level of each category. Section 4 verifies the effectiveness and feasibility of this model using a computational experiment. Section 5 draws the conclusions. Factor System of Sustainability Risk of PPP Project Risk management exerts a profound influence on PPP project management and its success [26]; especially, sustainability risk evaluations have been found to be highly variable, intuitive, subjective, Sustainability 2017, 9, 1890 3 of 22