BIM: What’s in it for Survey?
Geomatics World recently interviewed Derry Long on the subject of BIM
BIM is used most productively when it is applied to new building projects and, with the help of government, it has been pushed hard by the design software companies. Everything is new, from foundations upwards. Land surveyors are involved in surveying the site to show the area of land available and its relationship to existing structures and infrastructure and then, during construction, they may be hired to do setting out-work. Beyond that, their involvement is usually minimal and fragmented. However, there is the opportunity to be involved during the whole project life-cycle in providing as-built data, independent Industry QA and also providing a “basic” BI Modelling capability, to ease workflow. Since on-going and timely accurate and appropriate data is key to any fast-paced project there is also a role for surveyors to consult with the industry on the best methods and options for providing such data.
BIM for life
The focus has so far been on design and construction, but BIM is intended to run throughout the whole life of the building, up to and including decommissioning. Derry Long points out that very little has been said on what happens to the model when the site is handed over at the end of the construction period. During the lifetime of the building there will be a need to maintain the building model. If not maintained, it will soon go out of date, become unreliable and will lose its value. It is still unclear just who will do this maintenance work. Will it be work for facilities management companies, in-house maintenance staff or maybe survey companies will offer to keep the BIM up to date for the custodian? In order for this to be even explored there needs to be a greater integration of the project’s end-users as key stakeholders at the conception of a building and also in the maintenance of transfer of the BIM dataset.
As-built BIM
One aspect of BIM that has not been fully appreciated and explored is the value of the data and its reliability and currency. As we all know, it is rather easier to survey objects that you can see than those that are hidden and yet, for refurbishment projects it is usually the hidden objects, like a building’s steel structure that are specifically required and are vital to the project. As-built spatial information about these objects therefore has high value. These may be recorded on drawn ‘as-built’ drawings which are most likely to be design drawings stamped ‘as-built’ and then not maintained. A BIM used for construction will show the design position of structural members in the same way. Will engineers working on a refurbishment in twenty years’ time be willing to trust a BIM model any more than they presently regard as-built drawings?
In theory, the collaboration that goes into the BIM process should mean that buildings do match the design much more closely; and much has been made of the greatly reduced design changes that result when BIM is used to “virtually build and test” before going to site. However, there will always be as-built differences and surveyors could measure these during construction, when they are visible. Derry Long suggests that ongoing surveys should be made during construction with a view to recording the as-built position of detail, such as structural steelwork, and in real time, to capture it before it is covered up by finishes and decoration. The important point is that it is this valuable data that will be needed later in the life of the building when it will be difficult and costly, if not impossible, to survey. This is the equivalent of surveying underground utilities when they are visible in the trench, before backfilling. A brilliant idea, but how often does it happen?
Never or rarely, is of course the standard response, because the organisation paying for the survey is unlikely to be the one benefiting when the data is needed much later in the life of the building. However, this is not the only front-loading of fees on the entire project. The iterative virtual design process and sharing of data between critical professionals will largely happen in the early stages of the project in order to prevent pushing problems and issues further down the project line. How the fee paying client buys into this concept is currently far from certain.
BIM for refurbishment
Traditionally, most survey involvement has been with refurbishment of buildings. These are as-builts but will never be ‘complete’ because surveyors cannot see beneath the surface of the plaster without removing it. A measured building survey of an existing building will therefore never be as complete as a full (as-built) BIM. Without the detail within and of the walls, floors and ceilings, it is hard to see how any survey of an existing building can claim to be a full BIM. BIM ready or partial BIM – perhaps! So how will the world of BIM cope with incomplete building data? Laser scanning is part of the answer, but it is unfortunately being promoted by non-surveyors as a panacea. As so frequently is the case, the technology has been oversold and the expertise in using the data undersold. Martin Penney – survey director at Technics Group suggests: “The second part of the answer is providing the bulk of a BIM ready model, which simply allows the various end-users to then update the building fabric with specifics of type and finish. That is, allowing the ultimate users to focus on what they do best.” David Maltby also reckons that survey companies have not been proactive in communicating effectively with clients to solve their problems. He takes as an example a project to survey schools for a county council. The price for any survey company to carry out the whole job itself was never going to fly, so the solution suggested, and adopted, was for the firm to survey the building footprints and then train permanent and temporary council staff to survey the interiors; expertise that the council has retained for maintenance purposes.
BIM is not for all
It is also false to imagine that 3D BIM modelling will be suitable for every construction job and even when surveyors are asked to produce data for BIM, the specific level of detail required will vary. Derry Long sees a Survey Industry BIM specification and Specific Guidance Notes to practitioners, alongside training as a critical step forward, but says that this will take huge effort and perhaps most importantly support and buy-in from the industry itself in order to make it happen. Time is also against the industry as we are starting to bid for BIM tenders and projects alongside the normal survey requests, so impetus is building and the industry as a whole is no yet ready. He sees it as damaging for the industry if through a lack of wider professional guidance individual companies were to each produce their own specifications in order to make-do in the short term. We need to tackle the medium term now. Measured building models are part of BIM, but BIM is really about processes, data and collaboration. One aspect that measured building surveyors could tackle more effectively is the spatial planning issue that goes hand in hand with building refurbishment. Maltby says that clients are reluctant to have buildings surveyed that are going to be demolished, and yet it is an important part of the process to find out what space is being used in the old building in order to plan and build temporary accommodation (or the refurbished or replacement buildings). It may not be BIM as portrayed in the movies but planning of temporary works is none the less a vital part of the process and 2D is perfectly adequate.
Let’s be part of it
The survey Industry as a whole is beginning to wake up to the BIM notion and like everything there are the early adopters, avoiders and late adopters. Either way the industry needs drawing together on this topic for surveyors to make a coherent and concerted effort to be a part of the next generation of building management – from cradle to grave, or from site survey to occupation and ultimately redevelopment.
“This article first appeared in Geomatics World March/April 2013 and is reproduced with the permission of the author, editor and publisher.”
The article was written by Richard Groom and features contributions from David Maltby of MBS Survey Software Ltd and Martin Penney of Technics Group.
Geomatics World – is the trade Magazine of the Geomatics Industry .
