What is 4D BIM and what is used for
Construction site planning: how to improve construction time management and add value to your project with a 4D BIM model
Time management in construction is a process to efficiently allocate time and resources relating to work activities for a given project.
Traditional methods, such as producing Project time schedules, Gantt or Pert charts are fundamental on a tactical planning level, however, they don’t include the possibility to manage and reorganise timing in a dynamic and open manner.
For clients, designers and contractors, it would be helpful to be able to “visualize the construction site” already during the design phase in order to predict and plan all activities, especially when handling complex projects.
The integration of BIM into the project execution planning (4D BIM) ensures greater control over the model helping to prevent time and cost inefficiencies on site, facilitating the execution of relevant tasks, and making the whole process efficient including design, construction, and operation.
Let’s start off by exploring what is 4D BIM, what are its advantages for your projects and what tools to use to manage the fourth dimension of BIM.
What is 4D BIM?
4D BIM modelling is the process for creating intelligent connections between the 3D digital model (which defines the project geometry) and the information on the execution time of the various activities required for construction.
The result is a complete information model that can also be used to create realistic simulations of the construction process in terms of time management. The aim is to identify all construction activities (as in a traditional time schedule), to visualise their progress over time and to offer stakeholders the opportunity to identify, analyse and prevent problems related to the sequential, spatial and temporal aspects of the construction process.
With this data, designers can develop accurate schedules based on a reliable source of federated information making the process safe, improving control over conflicts detection between different activities, limits the occurrence of unpleasant surprises during construction and consequent waste of time and resources.
The difference with a traditional approach is that you are dealing with a three-dimensional BIM model, which can be visualised in an extremely realistic way and to which the fourth dimension, or time information, is added. The realistic simulation of 4D BIM improves the ability to understand information.
The concept of scheduling in 4D BIM
Scheduling is literally the planning of the time needed to complete a project. In fact, 4D BIM means defining the activities to be carried out with a timeframe and dynamically connecting them to the BIM model.
Planning is an essential feature of design because it allows difficulties to be prevented and anticipated right from the preliminary stages, so as to avoid mishaps and waste of time and resources on site.
Compared to traditional methods, construction planning allows spatial and temporal conflicts to be detected and problems to be overcome in advance through immediate programme updates.
5 advantages of 4D BIM
4D BIM can be the catalyst for an essential change in the way projects are designed, managed and developed in the construction sector.
Below are 5 aspects of 4D BIM that can improve the way you work:
- Planning and scheduling – AEC stakeholders can have a comprehensive picture of the project and its construction from the very beginning of the process;
- Real-time updating – 4D BIM provides a valuable aid to minimise the number and duration of meetings and phone calls to communicate decisions, changes and updates. Thanks to the visualisation of project progress achieved by 4D BIM models, communication becomes much simpler, clearer and more immediate;
- Project monitoring – the animation of the various stages of the construction process that you get from the 4D model can be of great help to keep track of everything that happens on site. What you get is a real video in which the various works foreseen in the project follow one another in temporal order;
- Conflict prevention and resolution – the existence of a shared information model adds transparency and clearly articulates the responsibilities of all those involved. Any additions or changes to the project can be easily traced back to the responsible person;
- Construction site safety – the use of a construction animation sequence to monitor the progress of the construction site also has great advantages for safety, both in terms of project data breaches and the risk of accidents on site.
What are BIM dimensions?
BIM dimensions refer to levels of information and data entered into a 3D model during the process of construction digitalization. In fact, BIM is more than just three-dimensional (3D) modelling for which it is mainly known and can embrace other “dimensions” that add useful information to the project to be managed. Here are the BIM dimensions explained:
- 3D – three dimensional graphical information.
- 4D – modelling scheduling information to model construction sequences
- 5D – cost management, construction cost estimating, etc.
- 6D – environmental, economic and social sustainability impact studies
- 7D – facility management: planning and management of maintenance operations throughout the building’s lifecycle.
In addition to the 7 standard dimensions, there is an open debate on the three “new dimensions of BIM”:
- 8D – safety during design and construction phases
- 9D – lean construction
- 10D – industrialisation of construction.
4D modelling tools
Let’s now take a closer look at what are the main 4D modelling tool features that allow you to connect a 3D geometric model to the 4D time dimension.
First of all, it needs to be clarified that 4D BIM modelling tools are software that allows associating of a series of information to the 3D BIM model that is relating to work execution time and to the organisation of the construction site. This information is displayed in a realistic way through animations that reproduce the progression of the various works and the progress of the site phases. In practice, it is a real video showing the site activities and the development of the construction work until its completion.
Any 4D BIM modelling software typically allows you to:
- break down the project into individual activities by defining a specific WBS (Work Breakdown Structure, i.e. a structured list of all project activities)
- associate BIM objects to the different activities
- obtain a Gantt chart
- simulate in Real-Time the evolution of the project over time and obtain realistic presentations
- identify and solve possible conflicts (overlapping of incompatible work, etc.).)
- federate different 3D BIM models
- add all the objects relating to activities even not directly connected to the construction work (for example: objects present in a material storage area, etc.)
- share the 4D model with your colleagues
- export the charts obtained in various formats.
If you want to try estimating the execution time of your project with a BIM software, download the free trial version of Edificius and try out the functions of the 4D – Gantt environment to simulate the evolution of the 3D model at the different stages of the project.
What is the difference between 4D and 5D BIM?
To recap, 4D BIM integrates 3D model data with project planning and programming data, generating realistic simulations of construction activities.
5D BIM, on the other hand, links all 4D information with the cost aspects of the project (material quantities, schedules and other cost information).
The integration of BIM to costs and times planning is based on project management, in particular project time management, and project cost management methodologies.
The BIM expert in charge of preparing the bill of quantities (5D) and managing the construction time (4D) has the task of linking all measurements not only to a price list but also to the parametric objects of the BIM model. This is done through the use of specific BIM software.
The parametric objects (walls, doors, windows, etc.) contain a whole series of information that helps to generate the calculation (quantity take off) and to identify the most appropriate price list item, having all the project information available.
In this way, the cost estimating can be prepared with extreme simplicity and by taking advantage of automatic systems that associate measurements (automatically obtained from the object geometry) and the price (usually taken from the reference price lists) with the parametric object to be calculated.
In short, 3D, 4D and 5D are three closely linked design aspects. By creating a WBS you can obtain automatic cost estimating (also interrogating the 3D model to obtain quantities) and the times of each individual process (evaluating price analyses in which the time used for each work process is also specified) to put them in sequence respecting good programming rules.