Fast, Accurate as-built documentation
As you draw to the end of a project and the momentum begins to fall, the focus turns to the as-built documentation.
Besides it being unacceptable for a client to be passed the original design model, all fancy and perfect, under the guise of ‘that’s what we have built you’ the responsibility remains that of the contractor to verify their work.
Moreover, designed with its perfect lines and exact corners where as in reality, even the best construction and installation teams work to a tolerance to dimensions on a drawing. Not being critical of the site crews carry out a good job for example site conditions may effect a change from the original design, technical issues have to be addressed at site and amendments made, all of which are recorded and signed off.
But how are these changes recorded. If a duct suspended from a ceiling is slightly out of place, does it matter? Probably not, but it should be recorded out of place. As part of a completed BIM package, accurate recording of building services is essential.
Indeed problems occur later, sometimes much later, when additional works or refurbishments are required, resulting in as-built drawings and BIM information being issued to new contractors and subsequently, additional costs are incurred which are in either event normally adsorbed by the client, especially when things are not as expected. Whereas the repercussions on the company for supplying the original as-built documentation in the first place are often overlooked.
Either way it is also important to remember that come the end of a project most services are covered or boxed in, so will it matter if it cannot be seen?
Now, it is well documented that the cost of making a design change increases as the ability to make the change decreases. Its easier to move an item when it is drawn on on paper than to physically move it when its 10 meters in the air or even buried in the ground.
So how can on site measurement data be collected efficiently and compared to the original design so that both contractor and client are assured that what they have built is correctly documented.
3D laser surveys
3D laser surveys offer an efficient, cost effective and safe way of capturing on-site measurement data, which is not only fast and non-disruptive to site activities, but also extremely accurate.
Not only does it capture reality and provide exact measurements, therefore it identifies that, not all walls are straight and have 90 degree corners, that not all pipes and ducts and sometimes doors and walls are in the exact location as the design drawing.
Above all, a 3D laser survey produces a point cloud, almost a by-product of the measurement acquisition. So without the need for any additional modelling, a point cloud can be overlaid onto the existing CAD model and immediately identify where alterations need to be made to the as-built documents.
As 3D laser surveys become a more integrated part of our design programme, we should look for innovations and embrace the technology to utilise it as a management tool throughout the project remembering a project can remain open long after the crews have left site.
Contractors should seek to have the correct information at the end of a project. Moreover providing not only the documentation, but the confidence and satisfaction that they have minimised unnecessary future costs. Furthermore clients and custodians should expect as-built verification as defined by BIM level 2 process specifications.