Articles regarding lean and BIM were categorized into two groups, namely, interaction and adoption and implementation. The results of practitioners’ opinions also were used to verify the findings of the systematic review and to present directions for future studies. Figure 7
a shows the word cloud of the transcriptions referring to the main relevant concepts, which were discussed around lean and BIM in the interviews. One of the keywords is people, who are the center of a lean system, and they need to be properly engaged in the lean process [53
]. Figure 7
b,c shows the dominant keywords used in the documents published from 2018 to 2020 (a) and documents published from 2010 to 2013. The word cloud shows that the first order of key terms is BIM, lean, and design. The second order of keywords is in the project, people, process, and waste from the practitioners’ perspective.
The second theme focuses on the need and challenges of lean-BIM applications in practice. This theme gives important insight into the barriers of the adoption process and mainly contributes to developing directions for future studies. While there is a rich literature on technology acceptance [55
] and BIM adoption [57
], there are a few systematic investigations of technology acceptance for lean purposes. Each theme will be discussed in Section 6.1
and Section 6.2 Figure 9
shows the frequency of themes and critical concepts discussed in three databases. The first database includes the articles identified in Search 2 (refer to Figure 1
), but limited to the first 3 years of the decade (2010–2012). The last 3 years of the decade are also selected from the beginning of the decade to the end. The frequency of concepts and words within two periods helps identify if the scholars’ concerns changed over the decade. Figure 9
shows that the concerns of BIM-lean concept adoption decreased at the end of the decade, and apparently, people are well aware of its advantages. However, the main concern would be small and medium enterprises (SMEs). Figure 9
also shows that other concepts received much attention, such as application development, big data, optimization, developing digital tools, and interoperability issues. Many current studies focus on the integration of these technologies for lean purposes [55
]. These topics would most likely be continued in the following decade to address the practitioner’s needs.
6.1. Theme I: Lean and BIM Interaction
Some articles studied the interaction between lean construction and BIM and implied that a synergy exists between them [61
]. Using Structural Building Information Modeling (S-BIM), a flexible environment is provided for collaboration and data exchange with the related fields to Set-based Design (SBD) implementation. SBD is a lean design that shares information and cooperates with relevant fields to omit wasting elements and grows productivity in all phases of a project. SBD is based on S-BIM enables constructability and economic efficiency analysis to improve efficiency [23
]. SBD provides for the use of a common language that enables processes to be effectively monitored by comparison against the standard (i.e., design).
The KanBIM concept is “a BIM-based lean production management system for construction.” This system provides interfaces of site specific to cope with the construction project’s limitation in managing the resource. KanBIM is a web-based collaborative interface that relates control to long-term plans and solves the controlling problem based on short-term decisions and vocabulary exchanges between managers and site teams. It is proposed that applying IoT standards for real-time task status report from the site can improve lean construction management systems such as KanBIM [47
]. In the KanBIM concept [44
], the use of visualization and pull-flow concepts incorporated into the project management processes enhances the ability to maintain flow and facilitate constant negotiations and commitments between teams.
One of the challenges to increase construction productivity is related to identifying the constraints, the resources of them, and the solutions for removing them. “A BIM-based technologically enhanced workflow” can be used to solve identified constraints and simplify the process of lean construction. Nath, Attarzadeh, Tiong, Chidambaram, and Yu [49
] proposed a workflow to improve productivity by 36%. Increasing the flexibility and transparency, communication, and collaboration between the project participants can facilitate and synchronize the workflow properly, which can be attained using BIM tools to enhance the lean construction effects on productivity [49
A new strategy for the design error management is presented by Al Hattab and Hamzeh [48
], which is based on structures of the team, interplay dynamics, and diffusion or propagation of error. In the lean-and-BIM-based environment, the information flow and communication between the project stockholders are increased [63
]. Thus, the application of lean and BIM for design error management reorganizes the design teams’ structure and communication for early errors identification, duplication reduction, and error diffusion restriction. In lean-based systems, error-proofing or poka-yoke is traditionally a vital part of lean production systems, especially when mistakes have been happened before [48
]. Therefore, lean-and-BIM-based environments have more potentials than traditional ones for detecting design errors and propagation diminishes [64
KanBIM presents situational knowledge to individuals, guides them to execute the accurate pull workflow, reduces the rework and wasted time. Thus its application enables process flow improvement and waste elimination [48
]. This is supported by responses from the expert interviews, where both lean and BIM present information that is accessible whenever it is needed. The information allows practitioners to monitor design processes and reduce “clashes” in scheduling.
Lean and BIM integration reduces the client’s change in orders, minimizes redesign, and reduces variabilities and enables the predictability of project time, the process of construction, and the drawings and documentation accuracy of the construction process. Simultaneous usage of these two concepts enables optimizing the overall time and cost and increment of quality to a remarkable level [65
]. As noted by our experts, BIM provides a constant source of real-time and accurate information that digitally enables work monitoring, rescheduling, and optimization. The literature identified several causes of waste in construction. For example, some of them are reported as a lack of clear goals and instructions for reducing waste, ineffective coordination and communication, and errors due to lack of details of design and construction processes [66
]. Figure 10
shows the main factors related to lean-BIM based on the practitioners’ opinions and verifies the finding of the present review. Figure 10
also shows key factors that should be considered in the construction industry, such as change adoption, developing relevant standards, and increasing the BIM-Lean practice in the industry.
The BIM adoption [29
] helps construction projects to achieve their goals regarding better and greener outcomes and provides an information model to solve the challenges of low productivity issues and to gain favorable results [58
]. The feasibility of prefabrication depends on BIM capability that may facilitate the supply chain’s coordination, including all the stakeholders and vendors [67
]. BIM is very important in the field of prefabrication as it prepares the facility of prefabrication scope management and off-site and on-site work packages coordination. The integration of lean and BIM can be effective for prefabrication, lean production, and supply chain implementation [68
]. The adoption of a “common language” and “clash detection” shown in Figure 10
facilitates prefabricated construction processes.
Computer-aided tools for visualizing and facilitating processes can manage data effectively to make the state of the process clear to all stakeholders (refer to Figure 11
), which is essential for advanced production management techniques implementation such as lean construction concepts [69
]. Managing by seeing has been an important approach for lean systems [46
], which would align with visualization tools provided by BIM systems.
Lean practices and BIM-based design can be effective in the design information flow. This new design management strategy relies on the dynamics of interactions and the accessibility of data to design teams. The design processes of lean and BIM can help design flow enhancement, the transformation of information, waste reduction, and generation of value [70
The KanBIM system is applied for the control of workflow on site that brings together the process and the product information in a unified way, with an interface and embedded support of BIM for lean construction workflows. This system has potentially positive effects on the site personnel’s ability to reduce wasted time. It can double the work scope that can be supervised reasonably [71
The collective role of BIM and lean construction theory can improve the construction project cost control, improve the project efficiency, and diminish the activities that are not value added, or may maximize the project cost, or are not align with the customers’ needs [72
The virtual design and construction (VDC) method is applicable to BIM as a new approach to manage data and organize users and their work methods [73
]. By implementing VDC and production management using lean methods, the achievement of performance improvement is possible. In the information flow phase, lean methods can be helpful for waste reduction within the VDC process. VDC enables the implementation of lean principles and incorporates management for waste elimination, costs reduction, productivity improvement, and projects’ positive results creation [77
By reduction or reliable prediction of output variability, lean construction goals can be realized, and a BIM-integrated simulation framework can be used to plan reliable production and enhance the involved parties’ efficiency in construction projects. Therefore, reliable production planning is significantly important for lean construction achievement [75
KanBIM system has a key role in individual decision support, coordination of team members, weekly negotiation about work plans, schematization granularity decrease to a diurnal level, real-time function restrictions assessment for calculating the task’s maturity, and the language/action prospect implementation [78
The experts verified the review findings in terms of the integration of lean and BIM. The results of the interview analysis showed that the role of stakeholders should be evaluated as a future direction. For example, an experienced practitioner stated:
“(a) User perspective of a lean design is that a person can move around an office environment or building seamlessly, and amenities are within a short distance.
(b) Designer perspective is that they can reuse the objects created, and there are less clashes between disciplines. Inter-discipline coordination will be made much easier and less reliant on Integrated Design and Construction (IDC), which is a waste.
(c) Construction Manager’s perspective is that the construction methods can be streamlined to remove waste during the construction phase. This includes the following: Construction sequence, Material flow, Information flow, Logistics, Labor & machine utilization; common language to use is: Non-value-add (NVA), Value-add & Value efficiency analysis (VEA), Constructability, Efficiency, Cost reduction, Visualization.”
The stakeholder’s role is significant since the network and the need for construction stakeholders are different from manufacturing, where was the origin of the lean concept. While BIM experts intended to explore how different stakeholders can commonly and collaboratively be coordinating and driving change [44
], there is a gap in the literature investigating how lean guidelines can be implemented in the modeling process to consider all stakeholders benefits. In particular, future studies should explore and offer models on how sensors and IoT can generate data and update BIM so that stakeholders can update their lean strategies in a near real-time manner. The literature analysis (refer to Search 2 in Figure 1
) shows that the number of studies investigating lean and digital technologies is increased. Figure 11
shows that there is a significant increase in 2017 and, most importantly, in 2020.
6.2. Cluster II: Lean and BIM Adoption and Implementation
A wide range of challenges in adopting and implementing BIM was identified, such as staff resistance to change, requirements of new workflows, less skillful people, a collaboration between internal and external stakeholders of the project, including architectures and engineers [80
]. The review revealed that the key challenges of lean-BIM adoption and implementation could be addressed by addressing key factors such as the change persistence, improving the awareness of individuals on BIM potential values, adapting available workflows to lean related processes, training BIM utilization, providing the required hardware resources and infrastructure for BIM implementation, upskilling team members, and recognizing stakeholders’ accountabilities. A bottom-up approach and top management support are needed for BIM implementation for individual engagement to use the prosperous strategies to reduce any possible persistence against change [45
]. After all, in a lean system, people are the center of everything, and it is important that internal stakeholders be engaged in the process [45
The concept of level of development (LOD) can develop BIM under the perspective of transformation, flow, and value (TFV) to manage the process of design based on the TFV theory and lean design management. The LOD framework makes it possible to apply design principles of lean via a practical usage of the TFV theory. The variables of LOD, the LOD matrix, and the BIM models parametric character simplify the TFV theory and design workflow management integration in the BIM projects [53
The main requirements for KanBIM performance are related to the subjects of the construction process conditions and its visualization of construction products, work manners visualization, planning support, discussion, feedback of obligation and situation, controlling the pull flow, workflow and consistency of plan, and manufacture experiments formalization to improve ongoing process [82
Visual management (VM) as a strategy of visual communication is a basic part of lean production. BIM-based visual management implementation is limited in the construction industry. The significant barriers to the VM strategy must be carefully addressed. The awareness about the VM benefits should be increased, and the VM business case should be presented to quantify its benefits for more VM execution. Besides the quantitative benefits of VM, its qualitative benefits should also be identified [44
The successful adoption of BIM depends on the prosperous alignment of BIM with work processes and readiness to project participant’s coordination. The practices of lean construction meet the improving project team coordination and present some instructions for coordination enhancement. Lean practices decrease the issues of coordination in the project organization and provide the BIM adoption way [83
Lean is regarded more as a philosophy or condition that is enabled by a set of tools such as Six Sigma. Womack, Jones, and Roos [84
] defined lean as the pursuit of perfection for which continuous improvement techniques such as waste elimination are seen as vital tools. BIM, on the other hand, is a digital technology that can aid waste elimination. In Cluster I, lean and BIM can interact to create a constant source of information and may also facilitate process optimization, reduce waste, reduce rework, enables monitoring, and enables digitization, which, in turn, enables visualization. Cluster II summarizes how lean and BIM both create a common language that can facilitate adoption in organizations. It is also noted that rapidly advancing technologies in IoT can act as enablers in both clusters.
However, many practitioners are divided over how lean and BIM are integrated from the anecdotal evidence gathered from our expert interviews. From our interviews, it is noted that some practitioners see BIM as a separate construction field of knowledge, while most would acknowledge that there are some areas of knowledge overlap. Awareness is one of the key influential factors at the organizational level, and adoption of lean and BIM can only be successful if people within the organization are aware of its benefits. Previous studies presented relevant factors as an intention to use lean-BIM, communication behavior, relative advantage, compatibility, and social motivations [84
]. As demonstrated in our literature review, there has been much research-specific areas of lean construction and BIM but much less on the benefits of a combined approach for these two concepts. Indeed, new technologies in IoT can act as an integrator of lean-BIM systems. IoT improves the process of generating information for lean purposes in an automated real-time manner in construction projects [28
]. This gives significant opportunities for lean and BIM to be presented as an integrated framework where overlapping areas of knowledge and synergies can be explored in future research. For example, Akinade, Oyedele, Ajayi, Bilal, Alaka, Owolabi, and Arawomo [28
] shows that an integrated cloud-based IoT tool can improve construction operation efficiency and facilitate the lean methods in prefabricated construction. However, the barriers of adopting and implementing the integrated systems of BIM-IoT for applying lean methods should be investigated specifically in different cases as future research. Figure 12
shows a set of critical components for lean construction and future directions of lean digital twinning.