**1. Introduction**

The construction sector has undergone many technical and regulatory developments over recent decades. Concerned about the impact of their projects on the environment and the safety of end-users and other project stakeholders, project owners have become more and more demanding when it comes to commissioning projects [1]. However, those involved in construction have, according to some commentators, changed their working methods very little [2]. This gap between changes in rules and standards that affect the demand-side, and the relative stagnation of those on the supply-side, has significant impacts on the duration, cost and quality of the works delivered. A project is an environment where stakeholders with different profiles are required to achieve specific objectives. The success or failure of a project depends on the strategy adopted to organize, coordinate, and supervise all the activities and works that need to be scheduled and then delivered while taking into account the various internal and external project constraints [3].

The planning and scheduling of construction projects represents an important part of the management of the construction process. It plays a crucial role in a project's success, since it facilitates the allocation of resources (such as equipment, materials, and labour)

**Citation:** Doukari, O.; Seck, B.; Greenwood, D. The Creation of Construction Schedules in 4D BIM: A Comparison of Conventional and Automated Approaches. *Buildings* **2022**, *12*, 1145. https://doi.org/ 10.3390/buildings12081145

Academic Editors: Yongjian Ke, Jingxiao Zhang and Simon P. Philbin

Received: 8 July 2022 Accepted: 28 July 2022 Published: 1 August 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

to project activities over time, to ensure the completion of the project on time and within budget [4]. In addition to determining the pace of the work, good scheduling enables project stakeholders to check project feasibility, estimate the preliminary costs, maintain safety, optimise the use of resources, and allow the project team to monitor and control progress and determine if the work is proceeding efficiently, ensuring that the client's objective is achieved [5]. Furthermore, planning and scheduling deficiencies [6] and poor communication among project participants [7] have been identified as major factors that can lead to project delays and cost overruns, and ultimately to claims and disputes [8]. As a major contributor to the global economy (13% of global Gross Domestic Product) and one that is expected to rise by 85% to \$15.5 billion globally by the year 2030 [9], the construction sector is still under-achieving and inefficient, since 9 out of 10 global mega projects encounter delay and cost overruns [10]. Scheduling software packages, such as Primavera and Microsoft Project [11], as well as planning techniques such as bar charts, time charts, and network approaches, are used to assist and help project managers in planning construction projects [12]. However, these tools are still limited and insufficient when considering the massive amount of newly-available data (e.g., feedback, images captured from smart devices, IoT sensors, etc.) that can continuously be produced on every project. Effective use of these data could enable valuable insights through a combination of Building Information Modelling (BIM), Artificial Intelligence (AI) and Machine Learning (ML) [13].

The advent of BIM has changed the practice of project management and has assisted project managers in expediting their duties more effectively than they have in the past. BIM can be defined as a set of tools, processes, and technologies that are enabled by a digital representation of the physical and functional characteristics of a built asset [14] expressed in data-enriched 3D models and their relationships. This digital replica constitutes a shared and central source of data about a facility, forming a reliable basis to produce information that supports insightful decision making for planning and managing a construction project throughout its entire life cycle [15]. Such information could include onsite spatial and topographical information, temporal and schedule information, and resources and cost information, among others [16–18]. BIM models are characterised by a level of development (LoD) which varies from 100 to 500 (i.e., from least to most developed) and serves to specify the appropriate amount of information required for specific uses [19]. Such digital representation is multi-dimensional, or 'nD', where each dimension indicates an information-processing capacity for various aspects [20]. The fourth dimension, known as 4D BIM, incorporates time-related information in the 3D information model to simulate and optimise the project construction process [21]. Practically, this consists of linking units of work or elements in the form of objects from the geometric 3D model to the construction scheduling activities using proprietary software, such as Navisworks or Synchro Pro [22,23]. Beyond the fifth dimension, understood as cost-estimating capacity [24], there appears to be lack of consensus [25].

Research has shown that 4D BIM can be a solution to overcoming many deficiencies of current planning practices [26]. The enrichment of a 3D BIM model with scheduling data has increasingly improved the quality of the construction planning process through the development and integration of several use cases, such as dynamic site analysis with temporary components including equipment movement, resource availability, the management of congestion and other operational constraints [27–29], spatiotemporal analysis for health and safety management [30,31], evacuation path planning [32], logistics management [16], augmented vehicle tracking and transportation route planning [33], construction waste management [34], spatial conflict detection and workspace congestion avoidance [16], and the monitoring of construction progress with site layout designs [35,36]. Overall, according to Candelario-Garrido et al. [37], 4D BIM simulation is 40% more efficient than conventional planning procedures. Furthermore, 4D-BIM-based visualisations provide an intuitive comprehension of the construction process which enables more effective communication and therefore better collaboration between all project stakeholders [38,39].

Although the benefits of 4D BIM are clear and much reported in the literature, few studies have considered the actual implementation of such tools and the corresponding processes during the construction phase that involves many actors. The use of 4D BIM is currently only adapted for small projects with few activities, since its use can be very expensive and time- and effort-consuming [23]. Moreover, there is little research addressing how 4D BIM can best be coupled and used with AI tools; e.g., to optimise and develop more effective strategies for construction project management through the automatic generation and simulation of different construction scenarios [40]. To bridge this gap, this study first presents case-based evidence of the use of 4D BIM during the construction phase of a real project to understand how this tool can be practically implemented to support and assist the project participants in their mission. Second, to enable process automation and 4D tools development, this paper presents an ontology—known to be a useful AI tool in formalising specific domain knowledge including concepts, relations, and constraints [41,42]—dedicated to scheduling, planning, and 4D simulation, and demonstrates its application by populating the corresponding database and developing a digital tool for application within the context of deep renovation projects that are part of a large European research project known as the RINNO project.

The remainder of the paper is organized into five parts. After a brief review of planning in construction projects in general, Section 2 reviews the literature on the use of 4D BIM, concluding in the identification of remaining barriers and problems for investigation. In Section 3, the sources of empirical and theoretical data are introduced. These include a literature review of 4D BIM applications and a survey of 4D BIM practice in France. The construction of a new building at the CESI campus in Nanterre-Paris prompted the overall study of a newly proposed approach to the process of 4D BIM implementation, which is detailed in Section 4. The proposed method is then demonstrated on the Nanterre 2 CESI Project in Section 5. The ontology proposed, along with a digital tool to automate the process of 4D BIM simulation specifically dedicated to scheduling of renovation projects, is introduced in Section 6. The CESI 4D BIM methodology was applied under unique circumstances and its more general applicability to the construction industry is discussed in Section 6 alongside the RINNO project case study, and the future work envisaged by the research team. The content is summarised in Figure 1, below.

**Figure 1.** Methods, contributions, ongoing works, and future developments presented in this study.

#### **2. Planning of Construction Projects**

The ISO 21500 standard defines a project as "a unique set of processes consisting of coordinated and controlled activities with start and finish dates, undertaken to achieve an objective" [43]. In order to achieve these deliverables, the processes comprise a set of activities to which human, financial, and material resources are allocated. These activities are also limited in time. The total duration of the project is the sum of the durations of those activities that are 'critical' (i.e., those in which a delay would cause a comparable delay in the completion of the project [44]). The definition given by the standard [43] also addresses the importance of the constraints that may be external to the project (regulations, socioeconomic situations, environmental issues, etc.) or internal (the availability of resources, the degree of skill of the actors, budget envelopes, etc.). A project is also characterized by a life cycle in which each of the stages requires the implementation of groups of processes to organize and control the work of the stakeholders in order to achieve the initial objectives. This life cycle depends on the nature, size, and field of activity, as well as the constraints of the project. Project management consists of identifying, planning, and controlling the processes required to increase the probability of the project's success at each phase of the life cycle.
