The industry 4.0 era is undergoing disruptive changes caused by new technologies, while data and technology are significantly improving people’s work efficiency [1]. Within this context, adopting and applying digital technologies has become an inevitable choice for various industries and enterprises to sustain competitiveness ^[2][3][4][2,3,4]. However, the construction industry has fared poorly in the process of digital transformation, ranking at the bottom of the 22 industries in terms of digitization level [5]. As the construction industry is project-based, the digital transformation of the construction industry or construction enterprises is considerably determined by successfully digitalizing construction projects. However, the digitalization of construction projects has been deemed a challenging task, due to the unique and temporary nature of construction projects, as well as their increasing scale and complexity [6]. Therefore, realizing the digitalization of construction projects is of great significance to foster the digital transformation of the construction industry.

Digitalization in the construction industry commonly refers to using digital technology to fundamentally change construction processes, thereby improving construction output and productivity to achieve enhanced project outcomes and better client satisfaction [7]. Currently, various digital technologies—BIM, autonomous robots, cloud computing, 3D printing, the Internet of Things (IoT), augmented reality (AR), and big data analytics—have been introduced, and they have brought progress to the digitalization of construction projects ^[8][9][8,9]. They are expected to bring transformation in project delivery and significantly improve efficiency and productivity, yet they are still far from reaching their full potential ^[10][11][10,11]. For example, BIM, one of the most widely adopted digital technologies in construction projects, has great potential to add economic, social, and environmental value to projects by deepening collaboration between stakeholders and integrating information in the project lifecycle [12]. In practice, its adoption among participants and application in project tasks is limited ^[13][14][13,14].

In essence, digitalization is a socio–technical system whose effectiveness depends on the degree of coupling between the social and technical aspects of the system ^[15][16][15,16]. The simple adoption of digital technologies in organizations without the corresponding technology-mediated organizational shift results in the underperformance of digitalization ^[17][18][17,18]. To exert transformational digitalization on the whole organization, organizational issues need to be considered in the design and implementation of digital technology. Integration is considered a primary characteristic of digital technology, which can support integration between and within organizations [19]. In construction projects, digital technology should promote project integration and optimize project outcomes [20]. However, recent research has reported that current organizational factors, such as project stakeholders’ skepticism and resistance to digitalization, lack of clear benefits, and stakeholders’ lack of digital experience and knowledge, significantly restrict the integrated function of digital technology in construction projects [21]. These unfavorable organizational conditions limit the application of digital technologies and obstruct project integration. It is, therefore, necessary to reduce organizational barriers by transforming the decentralized project network into an integrated organizational structure and ways of working. Project governance addresses the organizational structures and processes, as well as project roles and responsibilities assigned to stakeholders and project structures [22]. It provides the approaches, authorities, accountabilities, and processes to define the objectives of projects, the means to achieve the objectives, and the control process [23]. Therefore, it can adjust the project organization network to realize integration in digitalization through governing relationships of various participants and forming inter-organizational coordination.

2. Digitalization of Construction Projects and Integration

2.1. Digitalization in Construction Projects

Recently, the focus on the digital transformation of the construction sector has increased dramatically from both academia and practitioners, particularly with the impact of the COVID-19 pandemic and the rise of remote work. Commonly, the digital transformation process can be divided into three stages, namely digitization, digitalization, and digital transformation [3]. Digitalization is a process in which digital technologies are used to optimize business processes ^[11][24][11,26]. In the construction industry, digitalization is mainly implemented on construction projects and is the requisite stage moving toward company and industry-wide digital transformation ^[25][26][27,28]. Scholars have interpreted digitalization in construction projects from different perspectives, such as innovation ^[27][29], change ^[28][30], or socio–technical systems theory ^[29][30][31,32]. The socio–technical systems theory has advantages in explaining the interdependence between the technical and social aspects of the digitization system ^[31][33]. Whether digitalization is viewed as an innovation or organizational change, a primary reason for its failure is an excessive focus on one aspect of the system, commonly technology, without analyzing and understanding the socio–technical interaction ^[32][34]. Therefore, the successful implementation of digitalization in construction projects requires both actual technological installation and social adaptations of the project organization network ^[15][33][34][15,35,36]. Researchers in the construction field have extensively studied the technical aspect of digitalization and proposed various digital solutions. These solutions are mainly based on BIM technology, combined with other digital technologies, to collect, analyze, and present data from different phases in the project lifecycle to support project management (PM). For instance, the integration of BIM with real-time data from IoT devices can apply to areas including construction operation and monitoring ^[35][36][37,38], health and safety management ^[37][39], and construction logistics and management ^[38][40]. Virtual reality (VR) and wearable technologies were considered to expand BIM to effectively manage workers’ health risks and emergencies through pre-planning, education and training, and on-site monitoring ^[39][40][41,42]. Robotic systems and automation enabled by BIM were regarded as having great potential to improve construction productivity, reduce labor costs, and avoid injuries ^[41][42][43,44]. Unmanned aerial vehicles (UAVs) were also proposed to assess the project progress and perform compliance checks of geometric design models in conjunction with BIM [23]. Furthermore, the application of big data was introduced to support the management of projects and predict the performance of future projects through collecting, storing, and analyzing the massive volume of data in projects ^[40][43][44][42,45,46]. However, the implementation of BIM-based digitalization in construction projects encounters numerous challenges and setbacks, most of which lay on the organizational side rather than the technology itself. Sawhney et al. ^[45][47] pointed out that the conservative viewpoints of senior project leaders would lead to skepticism and resistance to change, resulting in a slow digitization process. Stakeholders’ inconsistent attitude toward digitalization was also regarded as an obstacle to digitalization, which is caused by their differences in digital capabilities and willingness to digitalize ^[46][48]. Additionally, even though construction organizations can share their digital resources with digital partners to gain a better competitive advantage, improved project performance, and risk reduction, it is difficult to achieve in practice because of the poor definition of goals, trust issues, partnering risks, and investment cost ^[8][47][8,49]. However, little attention has been paid to organization-related features of digitalization, and there is a lack of research on addressing the organizational barriers to the digitalization of construction projects from the standpoint of PM.

2.2. BIM-Based Integration

BIM has been widely viewed as a revolutionary technology in the construction industry and plays a vital role in the digitalization of construction projects. It is a fundamentally different way of creating, using, and sharing building lifecycle data, and it can bring benefits to every aspect of the project lifecycle from planning to demolition ^[48][49][50][50,51,52]. Miettinen and Paavola [10] summarized four ambitions of BIM implementation: (1) all relevant data needed in the design and construction of a building will be included in a single BIM model or are easily available with BIM tools; (2) a tool for collaboration allowing new integrated ways of working through data interoperability; (3) being maintained and used throughout the lifecycle of the building; (4) considerably increasing the efficiency and productivity of the building industry. By combining with other digital technologies, BIM is further expected to support PM by facilitating integration in projects from three dimensions: stakeholder integration, PM knowledge integration, and lifecycle integration. BIM has been shown by many studies to foster collaboration between stakeholders. By building a BIM-based digital platform, information can be shared between stakeholders in a unified and convenient way, both on-site and off-site ^[51][52][53,54]. This can promote communication and collaboration, thereby improving work efficiency; the knowledge and experience of participants can also be put into the project to contribute to the co-creation of value ^[53][55]. As for the integration of PM knowledge, some scholars indicated that BIM supports project integration management by integrating data from different PM knowledge domains ^[54][55][56,57]. By connecting functional subsystems with the BIM database, BIM can support the coordination of project schedule, cost, quality, resource, and other elements, simultaneously, to achieve optimal management of the whole project ^[56][57][58,59]. Using other digital technologies, such as IoT, the project data can also be collected and integrated in real-time to monitor and control project work ^[58][60]. Furthermore, BIM can also integrate data in the project lifecycle to support management and decision-making at all stages. This requires the continuous use and transfer of the BIM model between different actors to ensure that BIM functions throughout the project lifecycle. Based on this, BIM can integrate the management requirements at different stages of a construction project into the functional application of BIM and achieve efficient PM ^[59][61]. It can also support lifecycle decision-making by enabling data reuse in all stages ^[60][62].

3. Project Integration and Project Governance

3.1. Project Integration

The construction industry has long been deemed fragmented and unintegrated, which encourages adversarial relations, incurs conflicts between activities, and leads to productivity reduction and variability in project performance ^[61][62][63][63,64,65]. Therefore, project integration is believed to significantly improve project performance, which researchers have interpreted from different perspectives, such as coordinating processes ^[64][66], improving the integration of information and knowledge ^[65][66][67][67,68,69], promoting innovation ^[68][70], and managing risks comprehensively ^[69][71]. Project integration also plays an essential role in promoting the digitalization of construction projects, as it fosters inter-organizational cooperation and creates an environment for the exchange of digital resources between actors ^[63][70][65,72]. This cooperation across organizational boundaries reduces their learning costs in digitization and creates benefits for them by uniting the resource portfolios and activities of different actors, thereby increasing their acceptance of digitization ^[71][73]. Thus, a circular flow of information and resources between stakeholders can be formed to continuously identify and seize opportunities throughout the project, leveraging digital technologies to create more value for the client ^[72][74]. Existing literature has discussed the enablers of project integration from different dimensions. Halfawy and Froese ^[65][67] believed that the integration of multidisciplinary project processes throughout the project lifecycle can be achieved based on an integrated project system. Rutten et al. ^[73][75] indicated that the systems integrator undertakes the responsibilities of designing and producing CoPS (complex product systems) and adds value through system integration, thus playing a role in establishing and coordinating inter-organizational innovation in construction. Braglia and Frosolini ^[74][76] stated that the project management information system can be integrally implemented in extended enterprises to manage complex projects by adopting shared communication, common standards, and appropriate software tools for managing supply chains. The results of Zhang et al. ^[75][77] revealed that leadership styles have a mediated effect on the relationship between emotional intelligence and collaboration satisfaction in an integrated team. Oppong et al. ^[76][78] pointed out that a collaborative integrated project solution can be achieved through integrating the diverse needs, interests, and objectives of stakeholders into the design of a project. The empirical results of Shen et al. ^[77][79] verified that formal practices and social norms can improve interface management behaviors and achieve communication and coordination between different parties in EPC projects. However, most of the research on project integration focuses on the integration of a certain dimension, while the research on promoting systemic project integration in the digitization of construction projects is still lacking.

3.2. Project Governance

Although the existing literature does not explicitly describe the relationship between project governance and project integration, the close relationship between them is indirectly reflected in literature ^[78][80]. Project governance can form cooperation and consistency among participants through contractual and relational governance mechanisms ^[79][80][81,82]. Contractual governance controls and coordinates the expected behavior of participants through formal rules, terms, and procedures. It sets out principles, general procedures, and primary responsibilities for all participants to guide the accomplishment of tasks; it integrates resources and maintains collaboration to achieve valuable creations ^[81][82][83,84]. Relational governance is an informal mechanism that enhances the social ties of participants by forming relational norms and trusts ^[79][83][81,85]. By sharing norms and values among participants and cultivating mutual trust, it can promote the coherence of partner interests and reduce opportunistic behaviors ^[84][86]. It is, therefore, beneficial to the implementation of planning and the achievement of consistency in the project process ^[80][82]. Thus, project governance can establish coordinated actions of different parties in implementing digitization, through formal or informal means, to facilitate project integration. A project governance model provides comprehensive and consistent methods to control the project based on contractual and relational governance mechanisms. Considering a project as a nexus of both internal and external treaties that is governed by a structure of organizational arrangements, Winch ^[85][87] described the project governance model as a three-level system that includes the institutional level, the governance level, and the behavioral level. The institutional level set the ‘rules of the game’ in the project environment, thereby reducing uncertainty in organizational and individual decision-making. The behavioral level includes how managers typically respond to tasks. The governance level mediates between the institutional level and the behavioral level, and it includes the tectonic approach and process of an organization.