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BIM: Grasping the nettle

Building Information Modelling is becoming increasingly sophisticated, although Adrian Greeman says that the complexity of civil engineering projects means that many have yet to fully embrace it.

Development of international standards for civil engineering design software would help speed up the adoption of Building Information Modelling in infrastructure says BIM expert Arto Kiviniemi.

The development of Building Information Modelling (BIM) for construction has been gathering momentum worldwide, not least because of government initiatives in Scandinavia, the United States and the UK. BIM involves the use of information rich three-dimensional models in place of two-dimensional drawings. The models are interactive and contain information about materials and equipment used, and vital maintenance and operation information.

Either across the board or for major public clients BIM is mandatory, or is soon to be so. In the UK all government projects must match what is called level two BIM by 2016.

Building sector take up

While architectural and structural engineering, and mechanical and electrical specialists in the building sector have increasingly taken up this technology and the radical workflow and method changes implied by its use, the “step-change” is happening less quickly for infrastructure. Far fewer road or rail projects have fully utilised BIM. There are exceptions, like the huge Crossrail scheme, and Balfour Beatty’s M25 widening project, which incorporates BIM techniques particularly at the construction level. But in general civil engineering uses less full BIM.

One reason for the difference lies in the type of software available and the way it works, and particularly the use of object based components in models, instead of lines and points. Behind that lies an absence of standard definitions for those objects, particularly the internationally agreed open definitions for interoperability known as industry foundation classes (IFCs).

Objects allow elements in design software to be “intelligent”. They have attributes attached to them so that if you click on a wall or a door in Autodesk’s Revit program, Tekla’s architectural program or ArchiCAD, a host of detail is available. Wall dimensions, properties, perhaps the maintenance needs, the address of the materials supplier and almost anything else that might be useful, can be embedded.

“Models could be used far more extensively for cost assessments, energy use analysis and maintenance calculations”

Arto Kiviniemi

Beyond that an object’s attributes also let it “know” how it relates to elements around, so that if a window is placed in a wall, a space is opened in the drawing to accommodate it. Move the window and assorted features of the surrounding elements will change accordingly.

Components can be supplied with this “intelligence” attached by the component maker, for example. Models can accrete further information as design proceeds and projects move into construction.

Beyond geometric information

For the Finnish government, getting beyond simple geometric information was important says Kiviniemi, currently a professor at Manchester Salford University’s built environment faculty and a frequent speaker at BIM conferences.

“It meant that models could be used far more easily by the client, and far more extensively, for making cost assessments, energy use analysis and calculations of maintenance needs,”
he explains.

Kiviniemi was the project leader for a £37M study carried out over six years in Finland which led to the recommendation to the government to make BIM mandatory. It subsequently became the first government to do so. From 2007 all buildings for the Finnish government’s Senaat property agency required such models from designers. This year he says it has gone to a second level, with all government work to be submitted as information models. Requirements have just been posted on the Internet in Finnish and will shortly be there in English.

The chosen format for submissions was the IFC standard. This left it open for the industry to use whatever tools and methods it wanted, as long as data could be exported in the open format.

“Change is not going to come from the Scandinavian countries because they are too small to have a major impact on the big vendors”

Arto Kiviniemi

The advantages have grown as the BIM concept has expanded. Increasingly the object attributes are a way to embed “as built” information and to communicate subtle design intentions. They can incorporate data which will carry through to the facilities management or asset management and maintenance departments for road and rail infrastructure. Whole life cycle engineering is becoming a reality and could easily provide economies and savings far beyond those achieved at the design and construction stages.

But in civil engineering these open standards do not yet exist, and neither do proprietary object definitions. Design programs are increasingly sophisticated, so that if the design of, for instance a road is changed, an “instant” recalculation can be made of its design characteristics, amounts of cut and fill and all the elements of the road assembly, if the alignment is changed. Autodesk Civil 3D has made a lot of headway with these capacities and now includes “assemblies” which get part of the way there.

But the BIM processes for civil engineering currently have to use a range of procedures to attach most information to project models. One is the COBie standard method initially developed in the United States. COBie requires a set of specified information to be supplied in a standard table format, like a spreadsheet. This can be inputted manually or via tools which run parallel to the design software or which are increasingly being built into various types of software.

Eventually, the inclusion of even more detailed object attribute information can bring even greater advantages. In Finland this has helped stimulate the development of BIM software and new types of software says Kiviniemi. One making a lot of headway is model auditing software from Solibri which checks model compliance with various national standards or IFCs.

“It offers the prospect of putting things like building regulations, or energy use requirements into a computer readable form and auditing them automatically for compliance,” says Kiviniemi.

BIM challenge

One of the BIM challenges is to get the same level of definitions for civil engineering projects roads as for buildings, he says.

It is not straightforward because the long linear nature of roads and railway lines and their extended geographies bring complex technical problems, particularly in terms of geographical coordinates and referencing.

“There are some open formats, in XML, but development of the IFC definitions and their requirement by big clients would really push things,” suggests Kiviniemi.

“It is not going to come from the Scandinavian countries because they are too small to have a major impact on the big vendors.

“It was partly because the big US clients like the government property agency the General Services Administration and the Corp of Engineers started requiring BIM in building, that things moved along.”

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