B2 - Chapter 6 - Contractors

The main point described in chapter 6 of the BIM handbook, is the importance of contractor’s participation in the early phases of the design process. In all the chapter it is emphasized how this early and continual collaboration of all the parts involved in the building process can decrease the time and the costs of the construction. BIM is a useful tool that allows contractors, subcontractors, architects, engineers and owners to share information easily. Nowadays, this close collaboration is not really common, because, as it is discussed in paragraph 6.2, there are many small firm in the construction sector that are responsible for specific works. There is now the tendency for big companies to work on both design and construction process (Design-Build firms). For this kind of companies a BIM model can be really useful and I believe that this kind of companies should have a BIM office that coordinate the work of the different parts on the model. 

There are several features that BIM offers to facilitate the work of contractors. One of the most important, already available in almost all the BIM tools, is the clash detection. With 2D drawings, it is performed manually. It is time consuming, prone to errors and brings problems when the drawings are updated. On the other hand, with BIM it is possible to perform it automatically, thanks to several plug-ins or separate software as Navisworks or Solibri model checker. One of the other advantages that BIM offers is the quantity take off. This allows contractors to make an estimation of the costs easily. Indeed, many BIM tools provide capabilities for extracting counts of components, area, volume and material quantities. However there are no tools that can deliver a full estimate automatically from a building model. This is one of the features that, in my opinion, should be implemented in BIM tools. 

In paragraph 6.7, the construction analysis and planning related to BIM are amply discussed. There are some BIM software (for example Revit) that take into account the time variable through scheduling parameters. This permits the visualization of sequential construction of the building therefor an easier way of communication on the construction site, multiple stakeholders input (impact on traffic etc.), a better trade coordination and the possibility of comparing schedules and track construction progress. Other functions that BIM offers are discussed in paragraph 6.8, such as the integration in the model of other variables like safety management, procurement tracking and procurement purchasing. Furthermore, the construction sector is moving towards a greater use of prefabricated components to reduce the costs and time of construction and the risks associated with on-site installations. Prefabrication requires considerable planning and accurate design information. The exchange of a BIM information between contractors and fabricators can lead to a time saving by verifying and validating the model, reducing errors. 

In conclusion, as Timothy Perdue well discussed in his post, there is not a single tool that integrate all the requirements necessary for a successful implementation, but in my opinion this is the goal the BIM developers (such Autodesk or Bentley) have to aim for. Currently 4D models are available, as mentioned above they take into account the time variable. The future of BIM is to integrate directly in one software other variables such as cost estimating, sustainability and facility management applications. This is well shown in the image below, that I took from another lecture I had last semester at my home university, from Jan Holsøe, Business manager, MEP at the Swedish company Tyréns.

References:

Eastman, Charles M. 2011. BIM Handbook : A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers and Contractors. Hoboken, NJ: Wiley, 2011. eBook Collection (EBSCOhost), EBSCOhost (accessed January 21, 2015).