(The content of this blog post originates from an article published in the May 2021 in Concrete Magazine by Animesh Sourabh at MagiCAD. This is an edited version of the article. Contact our team for more information about Cubicost and RC frame take-off.)
The application of Building Information Modelling (BIM) can improve the efficiency and collaboration within the construction industry. However, BIM is not yet regularly used in RC frame take-off or measurements by estimators. Why is that?
Let’s first consider the key players involved and the application of BIM in the process of tendering (see Figure 1):
- Clients are usually inclined to see the application of BIM methods during the design stage. Yet, they would send out 2D drawings to contractors for tenders.
- Architects would sometimes produce BIM models in addition to 2D drawings. They are aware however that in case of any gaps, the client will hold them responsible on the basis of 2D drawings that they produced.
- Structural engineers have been the early adopters of BIM tools. They would typically generate 3D models for structural design, which are shared with the client but may or may not be forwarded to the RC frame contractors.
- RC frame contractors’ estimators use the 2D drawings to do their measurement in order to submit tenders under tight time restrictions. BIM models, if available, may be used for visual checks or not used at all.
The above mentioned approach comes with its own challenges. Design revisions take place in quick succession during the pre-construction stage. In such a scenario, the estimator would have to track these changes using a 2D drawing, factor in any interactions between different elements, align them with the measurement rules (Standard Method of Measurement 7/New Rules of Measurement 2) and adjust entries in the cost document (See figure 2).
A 2D view offers a limited context about a project. One can argue for the use of comments and markups however, capturing the interactions between different elements (columns, beams, slabs, etc) is far more difficult.
Exchanging 2D drawings (with comments and mark-ups) back and forth, either with your own QS team or with your client, hinders collaboration. Quantity surveyors would often do their measurements from scratch because it is easier in comparison to interpreting all the estimates produced from the 2D drawings by their estimating teams.
Let’s consider an alternative. What if the RC frame estimator was able to create a 3D model out of the 2D drawing? The raw measurements could be generated ‘on the go’ while factoring in any measurement rules or deductions. In addition, extra measurement, such as, formwork and reinforcement could also be created automatically (see Figure 3). Also, the quantities could be generated straight from the model and therefore they could be traced back to specific element or groups of elements, while being in a 3D view.
THE SOLUTION – CUBICOST TAS
Through Cubicost TAS software, companies including Byrne Bros, Addington, Stephenson Group, MPB Structures, Woodmace, PJ Carey and Moortown are already using this new approach to submit their RC frame tenders and improve their work-winning rates. Here are some of the benefits they have identified:
- Design changes are easier to handle as only changes to the model are needed which will then ripple across to revised measurements, deductions and any extra measurements.
- Additional context in terms of the 3D views from multiple angles are provided. The 3D model also provides a better view of how the elements interact with each other and how any design changes might affect those interactions.
- Better collaboration. QS teams can reuse the measurements produced by their estimating teams. Contractors can in turn communicate better with their clients about project progress as it is easier for everyone to be on the same page with 3D models and connected quantities.
The companies that want to take advantage of the benefits offered by BIM, now have also the tools to make it happen. It is now the time, not only for key players, but also for the larger RC frame industry to take note of the BIM-oriented take-off method. Contact us and let’s start a conversation.