## 2 Literature Review  
### Megaprojects  
Megaprojects refer to large-scale public projects with a large investment scale and high complexity and which have a significant impact on national politics, the economy, society, scientific and technological development, environmental protection, public health, and national security [17]. A megaproject is a complex giant system composed of multiple heterogeneous aspects driven by multi-dimensional construction goals, such as investment, benefit, and social responsibility, together with an organizational model, organizational culture, and other elements [18]. China's General Office of the State Council defines megaprojects as \"fixed asset investment projects that have been approved in accordance with relevant government approvals and have direct, extensive, and important impacts on economic and social development and improvement of people's livelihood\". Megaprojects are usually invested or commissioned by the government [19] and have far-reaching social impacts, from their design, construction, and completion to operation, and have an important national strategic significance. They can change the structure of society and have a multifaceted uniqueness and complexity in terms of the environment, program quality, and formation path [17]. Compared with more regular projects, megaprojects consume many social resources (such as materials, funds, and manpower) in the construction process, which has a significant impact on the public, environment, and government finance [20].  
In the field of construction engineering, megaprojects are mainly divided into two main categories [21] of infrastructure engineering and urban complexes. The former may consist of a single major project, such as the English Channel Tunnel, or several sub-projects that mainly serve the main infrastructure works, such as the civil works of bridges, tunnels, highways, and ports associated with the Hong Kong-Zhuhai-Macao Bridge project. The latter, on the other hand, is usually planned and deployed by the government or investors and may involve roads, housing, education, finance, entertainment, and other aspects, such as the Qianhai Development Zone and Shanghai World Expo. Both kinds of megaproject have three main functions: (1) to meet people's living needs; (2) to improve the social image of a location (e.g., a city); and (3) to meet the needs of major international events [22; 23].  
Due to the technical difficulty of engineering construction, a long cycle, a large number of stakeholders, and lack of experience, megaprojects involve increased uncertainties and risks in their construction process [7; 8]. As a result, they contain many hidden hazards, and accidents occur frequently. Take infrastructure engineering as an example; a total of 122 cases of bridge damage and collapse occurred between 2000 and 2012 [24] and a total of nine fatal accidents occurred during the construction of the Hong Kong-Zhuhai-Macao Bridge in Hong Kong from 2012 to the first half of 2017 [25]. Similar cases show that megaprojects are essentially high-risk tasks. Furthermore, accidents at a megaproject construction site not only delay the project, causing huge economic and social losses, but also lead to negative social repercussions and a potential decline in the country's international image [26]. The occurrence of the accident often arouses widespread concern and reflection from all sectors of society [27].  
In summary, while megaprojects can create huge economic and social benefits, they also have great production safety risks. Human factors are the major cause of construction accidents. Of these, 58% of accidents are caused by the poor psychological state of construction workers [28]. For a better understanding of the situation, this paper introduces the concept and measurement method of PSC and analyzes the PSC of megaprojects from the organizational factors that affect the psychological health of construction workers.