1. Introduction
Research into leadership has a long history. As an extensively explored theory, leadership has gained the attention of scholars worldwide, resulting in a wide variety of qualitative and quantitative approaches. Some scholars conceptualise leadership as a behaviour or personality, while others view it from a social information processing standpoint
[1]. For many years, the importance of leadership was ignored in construction project management, as traditional researchers in this field mainly focused on the technology of the project
[2][3][2,3].
The research paradigm of leadership in the construction industry began to change at the end of the 20th century. Across a broad research scope, early researchers conducted some interesting cross-sectional studies. For example, Sui Pheng and Lee
[4] attempted to construct a managerial grid framework with an ancient Chinese strategy to develop the leadership of construction project management, while Weingardt
[5] encouraged engineers to become more involved in leadership on all levels and to broaden their impacts on public policy. During this period, scholars realised that construction projects are people-oriented and that effective leadership is inevitably related to project success
[6][7][6,7].
Since the beginning of the 21st century, leadership has been documented as an important skill of effective project leaders
[8] and engineering management students
[9] to accompany their technical skills. The behaviours of the project leader were found to be more significant in the prediction of project performance than the other team members’ characteristics
[10]. Some quantitative and qualitative methods are gradually being introduced in the literature on leadership in construction projects. Liu et al.
[11] developed a model to examine the power structures of the leaders of construction projects, while Fellows et al.
[12] determined the leadership style and power relations. Odusami et al.
[8] analysed the data from 60 project team leaders and concluded that project performance is significantly affected by the project manager’s leadership style. With a rapidly growing body of leadership research in construction projects, a number of studies have been conducted to determine the factors that contribute to an ideal construction project manager’s leadership style from a variety of perspectives
[13][14][15][16][17][13,14,15,16,17]. Since the work of Turner and Müller
[17], the study of the leadership of project managers has gained new momentum. Turner and Müller suggested that research should pay particular attention to the project manager’s competence and leadership style in relation to project success. For in-depth research, Müller and Turner
[18] conducted qualitative and quantitative studies and concluded that the project manager’s leadership style influences project success and that different leadership styles are appropriate for different types of projects.
Over the past two decades, leadership has been regarded as a significant cause of project success or failure
[19], and the personal and interpersonal factors of project managers that contribute to project performance have been investigated to some extent
[20][21][22][23][24][20,21,22,23,24]. As shown in
Figure 1, since the first literature appeared in 1992, the number of studies has increased every year. Against this background, several studies have reviewed and analysed the existing literature. Toor and Ofori
[22] selected 49 studies and summarised the empirical research on leadership in the construction industry. Simmons et al.
[23] conducted a critical review that predicted some future trends. In Graham’s
[24] systematic review study, a computerised technique was used for bibliometric analysis to develop clear criteria to inform a thematic analysis and compare the analyses between multiple authors. Some other studies remain narrow in focus, dealing only with a certain branch of leadership theory in the construction industry
[25][26][27][25,26,27]. Most studies, however, rely on the subjective judgment of experts, which leads to a lack of quantitative bibliometric analysis in this field. Although there are increasing numbers of publications in this field, little is known about the overall structure of the knowledge landscape.
Figure 1.
The number of published papers on the topic “leadership in the construction industry” or “leadership in construction projects” (1992–2022). Source: Web of Science.
Scientometrics is a branch of informatics that was defined by Nalimov and Mul’chenko
[28] as “the quantitative methods of the research on the development of science as an informational process”. It can be considered as the quantitative analysis of patterns in the scientific literature to map knowledge structures and predict emerging trends in a research field. Compared with traditional bibliometrics, scientometrics provides in-depth quantitative analysis of the bibliographic information, such as countries, institutions, authors, keywords, and references
[29]. The applications of the scientometrics software reduce the impact of a researcher’s subjective opinions on document records’ retrieval and screening. By using visualisation tools such as CiteSpace
[30], VOSviewer
[31] and Histcite
[32], the knowledge structure of a scientific research field can be clearly presented. The scientometrics approach is the best way to explore research trends and key areas of study over time
[33][34][33,34]. Therefore, various visualisation tools have been widely used in the field of technology management analysis
[35]. By comparing the features of these software,
rwe
searchers found that CiteSpace, which can visualise the networks of cooperation and the development of a research area over time, had the most features and was the most used.
2. Transactional Lleadership
The “transactional leadership” cluster had the largest size in the construction leadership field, with a focus on the relationship between the leadership styles of project managers and project success. As a representative type, transactional leadership is used as a cluster label by the LLR algorithm. In the project management field, project success is a major concern and a recurring theme in the literature. Although there is still disagreement on what “project success” is, many leading scholars in the project management field agree with the point of view that the project manager is an important factor leading to project success
[36][55]. Therefore, the factors related to project manager leadership have received the most attention in this field of research. In the two most co-cited papers in cluster 0, D.A. Aga
[37][44] examined the mediating role of team building between transformational leadership and project success based on a field survey of 200 development project managers. At the same time, Muhammad Mustafa Raziq
[38][46] contextualised transactional leadership style and transformational leadership style in the project environment to clarify the impact of leadership style on project success.
Although cluster 0 has the largest size in the construction leadership field, there are still few studies directly exploring the relationship between leadership and program success. Zhang
[39][56] explored the mediation role of leadership styles between project managers’ emotional intelligence and other participants’ satisfaction. Tabassi
[40][57] proposed that the leadership competency of project managers is a critical factor in project success. Maqbool
[41][58] conducted a quantitative study on the Pakistani construction industry, and the results show that project managers with desired leadership competencies ensure higher project success rates. Some other representative works of literature use leadership as a factor in research models
[42][43][44][59,60,61]. An increased understanding of the factors that influence project success is very important for project-based organisations. Many factors affect the success of a project. The project manager is one of the most important of these factors. Therefore, project success as a criterion can provide a perspective on the leadership of project managers and can help in better understanding the mechanism of the project manager’s leadership
[37][44].
3. Safety Lleadership
With technological improvements, significant advances have been made to safety levels in the construction industry. The focus on safety has shifted from individual work to organisations. Meanwhile, there has been a significant increase in research on leadership and safety
[45][62]. For example, Hoffmeister
[46][63] explored the links between individual leadership facets and the safety outcomes of the employee. Mullen
[47][64] examined the moderating role of transformational leadership on the relationship between employer safety obligations and employee safety performance based on social exchange theory. Wu
[48][65] identified four dimensions of safety leadership practices to match the types of leaders in construction projects.
Much of the research in this cluster focuses on the safety performance of individual workers
[49][50][51][66,67,68]. However, the two most co-cited papers in this cluster developed multilevel models and introduced other research subjects. Wu
[52][69] proposed that the safety leadership of owners, contractors and subcontractors in construction projects affected each other and clarified the impacting paths. Guo B H W
[53][70] developed an integrative model to predict safety behaviour in the construction industry. Therefore, as the construction industry continues to develop, there is a need to develop a more comprehensive and integrated model exploring the mechanism of safety leadership in the construction industry.
4. Team Pperformance
Project teams are central to organisations. Due to the temporary nature of project teams, some project teams still cannot reach a stable and mature team when the project is completed, resulting in project failure
[54][71]. Hence, the effective operation of the project team must be highly valued in construction projects
[55][72].
The project team is composed of members with different demands, goals and expectations, and the team leader should motivate members in the early stage to form a team with consistent goals, vision and cohesion
[56][73]. As a temporary organisation, project team members often have different professional backgrounds. Therefore, the project manager’s ability to motivate members directly affects team performance
[57][74]. Odusami et al.
[8] ranked leadership and motivation as the most important skills for the project leader. Schmid & Adams
[54][71] emphasised that team motivation can be heavily influenced by the project manager, especially during the early stages of the project. Ralf Müller & Turner
[58][75]’s study came to a similar conclusion. Gehring
[59][76] argued that the ability of project managers to perceive the motivations and demands of project team members is the basis of team leadership. Moreover, the competency of project managers in providing task guidance to project team members has been shown in empirical research to impact project performance significantly
[58][75].
5. Leadership Iinteraction Pprocesses
Leadership is constructed and works in the process of practical interaction
[60][77]. Meanwhile, leadership is assumed to positively contribute to most modern organisations’ action processes
[61][78]. In practice, different interaction styles of the leaders and followers always imply different group productivity levels
[62][79]. Therefore, Carroll
[25] urged leadership research on the “practice turn” in social settings by leaders and followers in interaction. In this cluster, scholars’ interests focus on the leadership interaction between different project stakeholders. Chunlin Wu explored the leadership interaction between the key project stakeholders in his two studies
[48][52][65,69]. Limao Zhang developed a model to clarify the relationships between different stakeholders’ leadership and safety performance in a changing construction project environment. Furthermore, the interaction of the individual with the project environment is concerned in this cluster
[63][51]. The study of leadership interaction is interdisciplinary
[64][80], which requires collaborative research between scholars with different disciplinary backgrounds.
6. Actual Lleader Bbehaviour
The leader’s behaviour can positively impact role clarity and work engagement
[65][81]. Research in this cluster has focused on the impact of the project managers’ behaviour on project team members. For example, Naoum
[66][82] developed a model for the stress-coping behaviour of UK construction project managers. NannanWang
[67][83] conducted comparative research to reveal how project managers’ conflict-resolving behaviours affect project success. At the same time, Owusu-Manu
[68][84] explored the linkages between the project manager’s leadership style and mindset behaviour. The studies in this cluster offered a new, empirical insight into understanding the project manager’s leadership.