The 4th Dimension of BIM

This post is being composed from the CIOB AGM, conference and Members Forum in Dublin, Ireland. The opening day focused on a broad reaching BIM Conference.

BIM = Building Information Modelling. BIM is likely to be a game changing evolution in the way the ‘built environment’ is designed, built and maintained through life to the eventual decommissioning and either renovation or demolition of the structure. It is an evolutionary process with escalating levels of sophistication and information:

For more on the various levels and elements see:

BIM is becoming a world-wide trend; the UK Government has mandated the use of BIM on all major projects by 2016, contractors are taking the lead in the USA, BIM is routinely used in China and Hong Kong, and the Australian Sustainable Built Environment Council (ASBEC) is looking at implications in Australia. Used effectively BIM results in a significant reduction in waste, the CMMA-USA estimate up to 30% of construction costs are due to wasted materials, rework and wasted time waiting for information.

However using BIM is not just a technology issue. Some of the factors needed to implement BIM effectively include:

  • Managing the culture change and stakeholder issues to allow collaborative working.
  • Adapting contracts and insurance policies to allow the collaborative development and use of shared data. The CIOB have developed a new form of contract to assist in this, see: New CIOB Contract for Complex Projects.
  • Managing data exchange formats and other technical issues.
  • Designing the BIM model and Execution Plan; including deployment, quality assurance, ownership (stewardship) of data, defining the audience for the information extracted from the model and selecting the appropriate level of detail to put into the model and to extract from the model for different audiences.

Incorporating the 4th Dimension – Virtual Construction

The intention of this blog is not to provide a BIM tutorial, rather to look at the opportunities created when the 4th D of time is integrated into a reasonably sophisticated BIM model.

Adding the ‘4th Dimension’ allows the schedule to be linked with data objects at an appropriate level of detail and the project to be built virtually, testing different options before deciding on the best approach. Data from the USA suggests time savings of up to 10% are not uncommon.

Using the 4D model has many advantages. As a starting point, because the work can be seen in 3D, implementing concepts such as lean construction and last planner become much simpler. The workers can see what the current situation is and contribute effectively to decisions as to what work will be done in what sequence during the next few days and then see the results in virtual reality before starting on the actual work. This involvement can operate at the detail level such as services integration in a congested ceiling space or at a higher level looking at plant and materials movements. Some of the other opportunities include:

  • Using BIM to model the overall sequence of work on site. This is particularly useful for showing clients how the building will be constructed.
  • Using the visualisation to develop stakeholder engagement with the schedule at all levels from client to on-site workers.
  • Optimising phasing and temporary works, particularly on complex expansion and refurbishment projects.
  • Modelling the optimum vehicle, plant and material movements for maximum efficiency, particularly if there is restricted access.

Considerable skill is needed to integrate the schedule with the BIM model and make effective use of the information; a BIM expert will typically work with a scheduling expert to pull the data together.

A future extension of BIM could see the need to manage supply items removed from the schedule. The construction schedule defines when the element is needed, the BIM system knows what data items are included in the element and it should not be too difficult in an integrated model to then work back from the ‘install date’ to the required manufacture date and before that, the required design date for each item. The integrated nature of the data would make tracking and managing the supply chain a real-time process with everyone fully informed of the current situation and any issues or problems.

BIM also has the potential to shift planning from activity based scheduling to location based scheduling allowing the optimisation of workflows through a project. In fact with the increasing power of computers, it is possible to foresee a time when the process of scheduling changes from using traditional tools to a virtual construction space where the planner physically moves elements of the building into place in the optimum sequence (or tests alternatives), in the same way a Lego model is built, and the BIM system creates the schedule from the optimum sequencing information created in ‘virtual space’.


The CIOB is leading a number of initiatives to integrate effective time management back into construction management. The key initiatives are:

For any non-construction person who has read this far…… BIM is not an exclusively construction management tool, it works on any engineering project: Boeing use very similar systems to manage the development and through life maintenance of the Dreamliner!


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