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Building Information Modelling

BIM – measurement and costing

by Dick Barker, Director, Laing O'Rourke, Head of Model Based Measurement and Costing.

Dick has over 30 years experience, working in the UK, Europe, Japan, Africa and the Middle East, responsible for building and civil engineering projects as a contractor. He is passionate about using modern technology to find better ways of doing things and drive out some of the much talked about waste in the construction industry. Over six years ago, he established Privica Ltd with a group of enthusiastic like-minded colleagues, comprising civil engineers, architectural technicians, software engineers, product designers and technicians. During this time they developed the algorithms, processes and skills to populate Bills of Quantities dynamically from 3D object-based models. These have been applied to over 500 projects, ranging through highways, railways, water and sewage treatment, process facilities, residential and commercial buildings. Privica was acquired by Laing O'Rourke in December 2009, and are now established as part of an innovative team keeping Laing O'Rourke at the forefront of model based cost management and measurement.

Setting the scene

Most people in the industry will now have their own definition of BIM, and the majority will have a 3D model and data in there somewhere. The term BIM is to an extent limiting; it is not all about buildings with walls and roofs, we need to include roads, bridges, railways, process plants and infrastructure generally.

Competent functionally rich 3D object based modelling tools have been widely available for over 15 years. 3D models and computer rendered visualisations and virtual walkthroughs of the completed facility are often the norm on larger projects. Somewhere in the food chain from project inception to decommissioning someone has to define the scope of work and quantify it to enable budgets to be set, costs to be estimated, resources procured and the works to be planned; measured quantities have been captured in Bills of Quantities for years. Quantity surveyors are well versed in cost planning and contractors have been using computer based estimating systems for over 30 years. So are we not already doing BIM?

In my view, we start to scratch the surface of BIM when we use the best available technology to do thing faster and better, and eliminate waste and repeated work at the interfaces. To drive out the inefficiencies we need to normalise data, enter information once and reuse it many times, turning data into an asset. It could be as simple as entering the name and address of a supplier once in a single place at the inception of a project.

We found however, that the process of taking the existing set of design information at key stages of design development and 3D modelling it paid for itself just in terms of the identification of and as an aid to eliminating clashes and co-ordination errors. Once we developed the modelling skills and processes to dynamically populate Bills of Quantities from models, our services became in demand by being able to compete on cost with traditional methods but able to respond faster and leverage the core process of modelling to provide a visual record of what has been measured where.

Due to the speed of response created by auto-measurement we are able to influence and inform the design as it develops with the knowledge of quantum and cost, not just measure and cost the design, which is often too late.

Considering BIM from a measurement and costing perspective there are three important cornerstones of the process:

  • 3D modelling to generate the geometry of what has been or might be designed
  • Defining the scope of work in Bills of Quantities and dynamically populating the Bills with quantities from the model
  • Specification, auto-annotating the 3D and 2D drawings from the model as well as dynamically linking the Bill descriptions to the specification.

The core process of 3D object based modelling for measurement produces a model that can be leveraged for many other purposes at marginal cost: clash detection, construction sequencing, printing physical models, presentation and visualisation, speeding up the process of assimilating information about the project and communicating it to those who are not so adept at reading drawings.

Clearly if the designers are using 3D tools for design and we can utilise their models for measurement then we will be able to eliminate another element of repeat work. Even when we have received some of the best models from designers, particularly in the early stages of design development we need to augment them to be able to measure and therefore cost things that need to be considered but not yet designed.

Once we have made the associations between an object in the model, say a window, and the relevant items in the Bill of Quantities and specification on one project, we are able to re-use this on future projects, adjusting for project specifics but not reinventing the wheel. In this way we increase our library of valuable data assets, making future measurement faster and cost effective.

We have already achieved similar efficiencies by linking the Bills of Quantities to cost estimation systems. The cost estimate build-ups for a particular item of work, in terms of their rates of consumption of the necessary resources and productivity, are saved for future use. Once we have reached this state it is relatively easy to extend the estimate to include the embodied carbon values of the resources consumed and calculate the embodied carbon value of the facility. We add additional information and reuse that already captured for other purposes.

We are limited more by how we organise ourselves for BIM and the choices we make in terms of IT infrastructure and software than available technology. Almost everyone involved in a project has a contribution to make to the BIM; it is not another silo of service and we all need to consider the inputs we need and outputs we produce as individuals and what we can do to drive out the inefficiencies at the interfaces. The technology exists to achieve all of the things covered above, however we are not all using the same data structures, and we use a variety of different software packages that are not always interoperable. Even within a single organisation it's often difficult to resolve these issues, and it is compounded when we have many people from multiple organisations in multiple locations working on a single project. The IT infrastructure adopted has to be more than a reactive afterthought; it needs to be integrated and interoperable.

To reap the benefits we can no longer throw information over the wall from one silo to the next: design, quantity surveying, estimation, procurement, construction, operation etc.

New skills are required that cross the traditional boundaries; in our experience it takes something like seven years post graduation for what we call the Construction Process Engineer to be trained. They need to be versed in 3D modelling, design, engineering, construction technology, quantity surveying, be knowledgeable about databases, and have the technical skills to resolve difficulties at the interfaces between processes, on top of undertaking Continuing Professional Development in their core discipline of architecture, engineering etc.

Perhaps the most important thing we have learned is to do it, not just talk about it, and hone the processes, skills and data assets in a cycle of continuous improvement

Find out more

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Related NBS information:

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February 2011

 

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