BIM skills: Effective Coordination and Clash-Detection Processes in Pre-Construction Phase

In the context of BIM, the concept of dimensionality often appears in professional literature. However, the problem is that different authors define these dimensions, or aspects of BIM differently. However, this is not about expanding the dimensions from a mathematical point of view. From a BIM and mathematical point of view, the dimensions correspond to the third dimension - that is, in 2D and 3D. However, if we add another dimension to 3D, from a mathematical point of view, a 4-dimensional space would be created, and then a 5-dimensional one. In the case of construction and systems, or programs used for projecting, planning and control of construction, or the construction process, the letter "D" does not mean a multidimensional space, but individual information components that we assign to the model. Designations like 6D, 7D, etc. they are not uniform and for this reason misunderstandings occur. We therefore recommend not using these terms.

4D BIM

In the case of 4D BIM modeling, we place the 3D elements of the model on the timeline, which creates a simulation of the construction process, with the help of which we can move to any day of construction. In addition to an effective presentation, it allows us to solve situations, technological conflicts (time collisions) and possibly also inconsistencies in construction solutions that may result from the project.

We can create a 4D simulation in two ways. The first way is to manually connect 3D objects (wall, column, window,...) to items within the timeline. However, this method is very laborious and difficult to update in case of changes. The second way, based mainly on the essence of parametric modeling, is automated creation by defining whether individual technological and spatial properties are taken over by the building object and we can also determine their sequence of construction. The time schedule compiled in this way is based directly on the model and therefore reduces the possibility of errors, such as the omission of some components, building constructions, or incorrect technological sequence.

Closely connected to the 4D model is the measurement report, which is an essential part of the documents needed to create a time plan. If we use CAD systems, its creation is very laborious and in certain cases inaccurate. Individual structures must be identified and manually recalculated. In this process, errors occur due to incorrect calculation or omission of construction. However, if we use parametric modeling, the measurement report is an output that can be generated with a certain degree of automation based on the materials, objects, and elements used.

5D BIM

Adding another aspect to the information model creates a 5D model that extends 4D with a cost component. With the help of this model, we can monitor the exact need for funds in each monitored unit of the project's life cycle. Simply put, 5D makes it possible to better plan the financial side of the entire project over time.

After 5D, the authors agree on defining the individual components of the model. However, different authors differ slightly in other aspects, such as 6D and 7D. Some refer to 6D as life cycle management (Hitchcock, 2011; McPartland), or as facility management (Fredrickson, 2011; Regarding 7D, the authors are also inconsistent, some authors state that it is an aspect of facility management (Akillian, 2012; AIC 2013) , others define it as occupational health and safety (Hitchcock, 2011; Fredrickson, 2011).