3D models have become the norm for most construction and engineering projects during the last decade. However, many industry professionals and pioneering companies have realised that we shouldn’t be satisfied with just 3 dimensions. In fact, many experts are starting to talk about up to 8 dimensions, including volume (3D), time (4D), cost (5D), operation (6D), sustainability (7D) and safety (8D). In this article we will focus on 4D BIM models and their heightened reputation within the industry.
3D models are part of the past
BIM has become mainstream thanks to the UK Government’s strategy. However, BIM Standards don’t say much about the different dimensions found within models. In fact, for many years we thought that models could only have 3 dimensions. With the increasing level of information that BIM models can comprise, this ‘reality’ has now become outdated. The next dimension which is typically added to the traditional 3 dimensions is time – commonly known as the fourth dimension, even in physics.
Anyone working on construction or engineering projects knows that time is critical. Together with cost and quality, time is part of the most important set of requirements of a project. For this precise reason, time has proudly gained the universal recognition as the fourth dimension in BIM models. In a previous post we mentioned that BIM data is much more than just 3D models. The metadata attached to 3D models is in fact as important as the physical 3D model itself.
And one such metadata item that we can attach to models is time, thus creating 4D BIM models. Within this 4-dimensional model we can distinguish 2 types of uses, which we will look at next.
4D BIM models with time schedules attached as metadata
BIM models such as these include not only the relevant metadata for each asset such as description, material or size, but also the time schedule. In essence, once the project programme has been developed, it can be attached to the overall model and to individual models. This way, you can visualise the schedule within the BIM model without having to cross-reference an external file.
Everything is centralised in one single ‘source of truth’, thus reducing errors and abortive work. You are also able to select specific model elements, like a water pipe, and the model will tell you all the time information about it. For example, it can tell you when the pipe is supposed to be installed on site, and what other activities or models are depending on this activity. In more sophisticated models, it may even tell you when you should order the pipes and when they should arrive on site to ensure you don’t affect the critical path.
4D BIM visualisations
Another way to use 4D models is to create visualisations over a specific time period. This particular use is becoming increasingly popular thanks to its application for construction sequences. Starting with the federated BIM model, it is possible to use software tools to create animations in real time. For example, to show how a building is built from its foundations up to the roof. When used properly, the 4D BIM model is not merely a beautiful video of the construction sequence. Rather, it becomes a tool for evaluating and assessing construction methods, sequences, risks, suitability of plant and storage areas, amongst others.
Continuing with the example of the building, the 4D BIM visualisation can show where the different plant and equipment will be placed for each operation, highlighting any potential hazards to operators or the public. It can also highlight risks associated with storage areas clashing with the movement of workers or exclusion zones of plant.
The advantages of 4D BIM
Although it takes additional time to develop 4-dimensional models compared to traditional 3D, experience shows that it’s worth the effort. Some of the key benefits of using 4D BIM models include:
- Access time information within the federated model without needing to refer to external files.
- Use the 4D BIM visualisations as a communication tool for site teams to understand better the work and risks involved.
- Assess and eliminate risks associated with time-dependant elements, such as deliveries of material or moving plant.
- Improve communication and collaboration as a single team, bringing the planners closer to the rest of the project team.
- Ability to export the schedule and visualisations for sharing with other stakeholders at relevant points in time.
And in case you still have some doubts about 4D BIM, check out the following video:
Have you already tried introducing 4D BIM models to your projects? Tell us your experience in the comments below!
