BIM

Forward-Thinking Builders Use BIM on Greenfield and Brownfield Sites

Software is a key element in the architecture and construction world – as it is necessary to create and construct in today’s connected world. From design drawings to promotional images, via building construction, software is tracking the stages and presenting the results to improve productivity and ensure on-time delivery across the board. The data to support all this has to come from somewhere and has to be managed in a coherent way and the Building Information Model is perhaps the obvious place.

Gaining the benefits of BIM

With a new building on a pristine site, the benefit of BIM and the value of capturing data in digital tools is realized easily. The appeal of applying these same techniques to projects involving existing buildings and infrastructure is growing, but with the singular drawback of the cost of capturing the digital model of a building or site that exists only on paper.

With a new, greenfield development the model is developed in parallel to the design and construction phases, becoming an integral part of the design and decision making processes as the project is realized. With brownfield developments, involving pre-existing structures, the challenge becomes capturing sufficient data to retrofit a digital model to the site.  The complexity involved increases when you factor in not just the existing buildings and structures on site, but the buried assets of the utility and telecom infrastructure serving them.

It is easy to see how 3d scanning and point cloud capture techniques can be implemented to capture above ground assets and buildings. High resolution scanners can capture data at a range of scales from inside and outside existing structures, placing the scanned ‘image’ into real-world 3d space. For instance, an impressive multi-platform scanner can be flown on a UAV (unmanned aerial vehicle) or walked round site in a backpack. Scanned images are automatically resolved into vector data for editing and incorporation into new models and drawings, from where a host of facilities can support design decisions.

Visualizing the result

Understanding how a new development will fit into the existing landscape is an increasingly important part of both winning client approval and gaining appropriate planning permissions. Being able to show the context of a new structure as it affects or impacts the surrounding buildings long before ground is broken, can win acceptance for a development and ensure investment is protected. For cities like London, the development of citywide, 3d models of existing and planned buildings supports the ability to place a new development into the context of the existing neighborhood. Once in place, such a model can show exactly how a development fits with others: where light and shade are affected, how protected views can be assured, and what verified views can be shared with clients to show what future users will have to look at. Buildings still in the planning phase can be brought into the view to show how the city will (might) look post-construction.

Hidden utilities

So much for what we can see, but what about the hidden assets? If the underground infrastructure of a busy city is not adequately understood, it can have a major impact on the viability of a site and on construction schedules. Without careful and accurate verification of utility records, costs can mount.

Utilities have a responsibility to maintain records of their buried assets and to make the records available to legitimately interested parties. But each utility has its own records and combining these is the first headache to overcome. However, when it comes to the decision about where to dig – where to actually break concrete and how far down to go – relying solely on the single line representation of a utility route on paper or electronic device may not be enough. A breach in a mains water line is expensive to repair and a misplaced spade through a high voltage cable is just plain dangerous.

Seeing underground

Technologies to ‘see’ what is going on below the pavement and roadways are not new but the complexity they have to deal with is increasing by the day.  Electromagnetic locators, cable avoidance tools and signal generators have been around for many years providing a, typically hand-held, tool to check the position of cables or pipelines. Techniques using ground penetrating radar (GPR) provide a faster way to gather the necessary data and mounting a GPR scanner on a trailer means a steady driving pace is all that’s needed to get a view of the services in place, saving the expense of road closures.

GPR results still require a certain level of interpretation and experienced surveyors will balance the radar results against other evidence before confirming the position of an underground feature. Does the radar line up with the utility drawings? Is the co-incidence of drawing and radar result within an acceptable range?  Data can then be loaded directly into building information models and compared with the plans for new work, where understanding the location of buried assets can support design decisions that avoid costly re-routing of utility services.

It’s all about the data

And for me that is the key takeaway – it is all about the data. Increasingly sophisticated discovery tools are pushing out more and more data to produce a digital picture of assets above and below ground. The data management, display and rendering tools that support BIM need to be able to combine this data, supporting better planning and cost savings right from the early design stage.

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