The goal of this study is to identify, classify, explore, and understand decision-making complexity elements in major infrastructure projects (MIPs). This article puts forward systematic definitions of decision making, decision-making quality, and decision-making complexity. Based on literature reviews and an in-depth case analysis of Hong Kong-Zhuhai-Macao Bridge (HZMB), a comprehensive framework of decision-making complexity is developed, which divides the elements into six dimensions: technical, social, financial, legal, organizational, and time. The links between different dimensions are also illustrated. This article is expected to deepen our current understanding of decision-making complexity and to provide a fundamental point of reference in the front-end phase of MIPs.

In mega projects, the stakeholders may be exposed to significant on-site construction risk, especially the owners and insurance companies who take the most responsibility for the risk loss. It is difficult for insurance companies to diversify their risks by undertaking enough similar policies, and participating in on-site risk management has become an important method of active risk control. Based on the principal-agent relationship between the owner, insurance company, and contractor, this paper establishes incentive mechanisms for risk management considering the common agency and exclusive agency models. The results show that an insurance company's involvement in the common agency model creates external effects that can improve the utility of both the owner and the insurance company. The owner is then willing to provide a higher incentive coefficient, and the contractor's nonrisk and risk management efforts increase accordingly. From the owner's perspective, the influence of the participants' characteristics and external uncertainties on the incentive strategy are discussed. The results recommend that it is better for the owners and insurance companies to jointly establish a good cooperative relationship and build the incentive mechanism. The spillover effect has a positive effect on the cooperation between the two parties, while the impact of the uncertainty in risk management output on the cooperative relationship is negative. This paper contributes to the body of knowledge for understanding the on-site risk management considering stakeholders' participation and provides a practical mode for owners and insurance companies to implement active risk management in mega projects, thus achieving better risk governance of mega projects.

As one of the most important sustainability project management practices, prefabrication has been drawing increasing attention to project construction practitioners. However, due to the needs of high technology and large capital investment, there is a great challenge for suppliers to adopt prefabrication in mega project construction. Therefore, designing an adequate incentive mechanism has become a daunting task for the project owner, which aims to ensure a socially and environmentally friendly project delivery. In this study, an incentive model with reputational concerns from the perspective of the project owner was established and how this incentive affects supplier's effort and project owner's profit was investigated. By contrasting to the incentive model without reputational concerns, when the reputation incentive is considered in the incentive contract, both supplier's effort and project owner's profit increase. In addition, adding reputation incentive implies more expenses, thus the project owner may not want to take this strategy due to the potential expense increase. Therefore, the study also considered an incentive mechanism with constant total incentive intensity. By comparison, the result shows that this strategy is also useful which can improve supplier's effort and project owner's profit.

The large scale of construction in mega projects leads to significant environmental and socioeconomic impacts; thus, the projects should also exhibit greater social responsibility. Adopting green supply chain management in the construction process is an important way to realize the goal of sustainable development of mega projects. Because the green supply chain behavior during construction is mainly demonstrated by contractors, it is especially important to study the evolutionary trend of their behavior. Thus, to explore the cooperative relationship among contractors, this paper considers a lengthy construction period, multi-agent participation dynamics, and opportunistic behavior-all are key features of mega projects-and establishes an evolutionary game model. Specifically, a replicator dynamic equation is used to describe the long-term effects of the contractor's decisions. Equilibrium determinants are then analyzed and simulated. The results show that the initial probabilities of the two types of contractors (main contractor and subcontractor) demonstrating opportunistic behaviors have a significant effect on the direction of evolution of the mega project. The main contractor, who dominates the subsidy allocation by the government and project owner, should pay attention to maintaining a balance in the income distribution between him or her and the subcontractor. Additionally, there is an optimal distribution coefficient for the subsidy that minimizes the overall probability of opportunistic behavior. This paper provides a point of reference for the decisions of the main contractor and the subcontractor in the green supply chain of mega projects.