by Suranga Jayasena

BIM enables automated take-off, and more significantly the automated estimating in minutes if not in seconds by linking those to appropriate rate libraries. This has raised worries if the Quantity Surveyors will become redundant. Will they actually, is not a question to be answered; but a choice to be made by individual Quantity Surveyors”

Did BIM make you nervous?

Quantity Surveyors perform different roles. While BIM may influence most of them in varying degrees, the above context would directly affect the role of Estimating. This paper reviews whether the role of an estimator would actually become redundant in future because of the introduction of Building Information Modelling (BIM). It briefly answers two basic questions.
Will BIM become the standard?
Can a computer replace an Estimator?

Will BIM become the standard?

Twenty years ago, did we think that CAD would become the standard? Did computer ‘allergy’ among senior professionals prevent CAD adoption? Didn’t CAD find a solution on its own for the practical barriers by introducing a new layer of CAD Draughtsmen to the industry?

BIM’s ability to effectively utilize computers to efficiently overcome many drawbacks in present systems, and the measurable benefits it can bring to the clients and builders alike seem to assure it becoming the industry standard. Barriers in the Information Communication Technology (ICT) end for BIM application are negligibly small with the ever increasing capacities in terms of information processing, storage and communication. The demand for BIM will find its own ways to overcome the practical barriers for BIM adoption as did the CAD systems. It is obvious that BIM will become the standard; what is not known is when it will. However, the interest of those who are into BIM is so intense that the change will not be very far.

Can a computer replace an Estimator?

Software tools are available which can fully automate the quantity take-off. However, they are still not able to perform it to comply any of the Standard Methods of Measurement (SMMs) commonly in use. This is because SMMs come with variety of different measurement rules which are not built into these applications yet. Software developers have not ventured into this area probably because there is not enough demand for it from Estimators. The demand is further limited by the fact that most countries have their own standards resulting in a very limited market for each development. In existing applications, a building element modelled as a column in BIM will be measured by the computer as a column even if its length on plan is more than four times the thickness, while SMM7 does not allow measuring it under columns, for example. Nevertheless, given the fact that computer can interpret the necessary information from the BIM model to test this rule, proper coding in software will enable built-in application to automate quantity take-off. Thus, automated take-off to an SMM should not be impossible.

However, the current tools are capable of elemental quantities take-off with high precision. The elements in a building can be uniquely identified by using building specification standards like UniFormat or custom standard of an organization. Automated quantity take-off can record the quantities along with these identifiers. Automated estimates are generated by exporting these quantities to elemental estimate format which is linked to a price database where the prices are recorded against the said unique identifiers.

It is observed that the building industry is gradually moving from building construction towards building assembly. Historically, the concept that building is a unique product had hindered offsite production, to a considerable extent. At present, various economic, social and environment pressures urge builders for offsite production and assembly at sites. Interestingly, BIM will enable production of precisely coordinated building elements offsite. Many building element manufacturers already have their products’ models as BIM Objects to be downloaded from their websites or from central repositories. These objects can have complete specification and cost information, or unique reference to databases. BIM modellers can directly include these objects into their models. Object models of the other custom designed objects (elements) can be sent to manufacturers for offsite production. Amongst the benefits are high buildability and minimized construction time and wastage. Thus the effects are multiplicative for creating a building assembly industry which will make an elemental estimate more reliable.

At current level of technology, BIM can save 80% of estimating time. In other words, 80% estimators should have become redundant if BIM was the industry standard. Would this necessarily be the fact? Whatever said, BIM will foster a culture of freely exchanged views and information enabling all project stakeholders easily access and update project information helping to unify all phases of the project from inception to salvage.



About the Author:
Suranga Jayasena (Membership No. GG 0210)
B.Sc.(QS) (Hons), M.Sc.(Building)
Senior Lecturer at Department of Building Economics, University of Moratuwa, Sri Lanka