*4.2. Phase 2: To Identify Information Requirements and Relevant Workflows*

The BIM manager precisely determines all the parameters to be taken into account and integrated into the 4D planning. This preliminary work is important because it helps explain to project contributors how to adapt their traditional deliverables (schedules and models) in order to be usable within the framework of 4D planning. As such, the BIM manager can proceed in three steps as follows:

**Step 1:** To convert the client's objectives into SMART objectives if this has not been carried out in the specification document. Indeed, non-SMART goals are often open to interpretation, unfeasible, or incomplete.

**Step 2:** To determine what information must be produced to perform relevant 4D planning. When the 4D objectives require expertise that is beyond those of the BIM manager (e.g., environmental risk management), project actors, such as QSE (Quality Security Environment), CSPS (Construction Safety and Health Protection Coordination), and specialised BET (an engineering company), should be appointed by the client at the request of the BIM manager.

**Step 3:** To draw up a functional and pragmatic strategy and formalise it in the BIM Execution Plan (in French the convention BIM). Indeed, to share and use the identified information, a workflow must be put in place to specify: what digital tools are capable of exploiting the information; in which formats the information should be delivered; how the information should be produced, controlled and shared; and finally, what deliverables are expected.

#### *4.3. Phase 3: To Design a Project Schedule Adapted to the Use of 4D BIM*

To ensure quality, optimal coherence, and consistency between the BIM model(s) and the construction schedule, a working method is formalised, as follows:

**Step 1:** The provisional or final construction schedule (depending on the stage of the project) is obtained. This schedule will be the input to the design process described below.

**Step 2:** The MOE, OPC, and CSPS meet to study the general planning of the project and identify the phases that could represent health and safety risks for the project (e.g., complex construction methods, areas of high co-contracting, significant environmental risks, heavy traffic flow).

**Step 3:** Meetings are held as necessary between the OPC, contractors and project actors to study in detail the scheduling of tasks. The synthesis of all this information will make it possible to propose a preliminary solution that will then be integrated into the 4D BIM use case and using visualisation, will then be validated or amended.

**Step 4:** The OPC in charge of monitoring and coordinating the work must master traditional planning and 4D BIM based planning tools, because they are in charge of linking the planning to the BIM model. The BIM manager is also asked to verify that the BIM models have been modified according to the new granularity of the construction schedule.

This process should be formalised in a contractual document, such as the PGC (site management plan, in French Plan de Gestion de Chantier), under the responsibility of the project manager.

#### *4.4. Phase 4: To Supervise BIM Models Production for 4D BIM Use Case*

As noted earlier, it is common for French project stakeholders to partially achieve only certain BIM use cases initially required by the client. This is partly due to the BIM maturity and expertise of some project stakeholders and partly due to the disparity between the required and available LoDs. A further important factor is the way the BEP is elaborated. For the use of 4D BIM, it often consists of a brief and summary description contained in a section that is less than one page in length. The proposals below aim to optimise the content of the BEP to better elaborate and specify the implementation of 4D BIM.

**Step 1:** To explicitly mention the obligation to achieve 4D use and above all what its purposes are. Thanks to the work carried out in Phase 1, 4D applications are easily understood using the SMART objectives identified.

**Step 2:** To detail which actor must perform or contribute to which task(s) in order to achieve the 4D BIM use objectives. To do so, the RACI matrix (Responsible, Accountable, Consulted, Informed) was proposed. This project management tool [99] is usually used for classifying project stakeholders through a 'responsibility assignment matrix', thus developing a grid specifying who does what in the project. Here it was adapted by the authors for specifying the scheduling process (Figure 4) and the BIM model production (Figure 5) to facilitate the use of 4D BIM.

**Step 3:** To indicate in the general process describing the BIM model's production when the tasks related to the 4D BIM use case must be performed. This must be undertaken before the BIM models are checked and coordinated so that the BIM manager can control deliverables produced for executing the 4D BIM use case and verify the presence of the parameters that will serve to link the BIM models to the schedule.

**Step 4:** The process of 4D BIM implementation needs to be very detailed to indicate to the project actors the method adopted. It should begin with a reminder of the SMART objectives envisioned; the modelling rules to comply with the rationale for model structuring and breakdown; the parameters to be created and information on who provides them and when; information on when and how the work will be controlled; the criteria for choosing 4D BIM software; and information on who links the model to the schedule to produce the expected deliverables, and when this will occur.

Clarifying and detailing the process and procedure for implementing a BIM use case, whether it is 4D-BIM-related or not, allows project stakeholders to have a good understanding and clear idea of the tasks to be performed. The more the production and control process is explained, the more the probability of reaching the project objectives increases.

**Figure 4.** RACI matrix for implementing the scheduling process when using 4D BIM.

**Figure 5.** RACI matrix for BIM model production when using 4D BIM.
