BIM is the industry buzzword this year. But does everyone know what it really means? Adrian Greeman finds out.
Suddenly everyone is “doing BIM”, or building information modelling. In the last 12 months the big consultants, clients, contractors and software suppliers have all become enthusiasts, issuing reports, appointing “BIM champions”, and populating strategic conferences and BIM workshops. Assorted software is suddenly packaged as “your BIM tool”.
The government wants everyone else to catch up, at least to a basic standard called Level Two BIM (see diagram, p21). It set out a target date of 2016 for all public projects to use it in its May Construction Strategy report (NCE 9 June).
“Virtual run throughs of operations can locate and identify risk points much more efficiently”
David Philp, Balfour Beatty
But ask what BIM actually is, and a dozen different definitions emerge.
“What it means tends to vary according to where you are in the construction chain and what you do with it,” says Phil Jackson, a civil engineering consultant now working with software vendor Bentley Systems.
For designers, BIM is the use of 3D computer models rather than basic CAD, and the matching up and integration of such models from disciplines ranging from groundworks to building service installation.
The integrated model allows conflicts and clashes, that traditional two dimensional working might miss, to be spotted while enabling virtual construction to be carried out.
Multiphase and complicated projects such as Terminal T2 at Heathrow, the extension of Victoria Tube station, and the reconstruction of Manchester’s Grade II listed Town Hall and library can be done with precision and speed, modelling complicated spaces or threading through spaghettis of underground services and foundations.
From another perspective visualisations generated from the model facilitate design reviews for the engineers themselves, for the follow-on construction team and most of all for the client and perhaps public community relations too. A virtual walk-through for non-engineers means far more than incomprehensible plan diagrams, helping avoid misunderstandings and expensive late changes because the building is not doing what was expected.
Consultant Arup is even using games software to measure and time multiple public walk-throughs of virtual models on the web, to test design suitability.
For contractors the issues are different. Foreseeing clashes on site is important too, but now these are much more to do with buildability and construction sequences.
Changes on site
Conflicts reflect changes on site as construction proceeds, as well as the need to accommodate and move big machines and install temporary works. They also reflect the ability of different trades and skills to fit in their work.
Using BIM, the supply chain can be better integrated.
Using BIM for sequencing is important and the capacity to show staged development of a site is highly useful. Increasingly cost and payments data, perhaps energy and carbon information, and sometimes other dimensions too can be incorporated.
“And safety is a vital advantage,” says Balfour Beatty Construction Services BIM programme manager David Philp.
He is currently seconded to the Cabinet Office to carry out BIM implementation. “Virtual run throughs of operations can locate and identify risk points much more efficiently,” he says.
“The equivalent in civil engineering would be the capacity to pull in a whole roundabout from a pallet”
Mark Bew, URS Scott Wilson
A host of different software tools already exist - at consultant Parsons Brinckerhoff over 45 packages are used, says one of the firm’s BIM specialists Rachel Arulraj.
Many of these are 3D design tools such as Revit, Bentley Architecture and ArchiCAD for structures, or a wide variety of civil engineering tools from the mainstream Bentley MX and Inroads packages. There is also growing competition from Autodesk Civil 3D, and numerous upcoming alternatives like the Australian 12D Model road suite, and the increasingly popular Professional Design Suite (PDS) from Causeway Technologies.
Most have capacities to handle laser point cloud data, now so important that Bentley Systems has just bought specialist software house Pointools, to integrate its handling capabilities. Most can generate rendered visualisation.
But a “killer app” in recent years has been Navisworks from Autodesk, which is able to accurately marry together 3D models, and sometimes 2D CAD as well, into one space, and which allows 3D sequencing to be built easily.
It works for designers to integrate models but has particularly taken off for practical site work at contractor level. Its ability to automate clash detection is a key feature which unsurprisingly vendor Autodesk holds back for the top level version, but it has also found a major role in facilitating teamwork. The program’s visual model has rapidly become a central feature of weekly site meetings.
There are some competitors. Bentley Systems has Navigator which uses a different method to bring models into a single “container” a bit like a multilevel 3D PDF. There is also Synchro, which ties 3D models together with critical path information, or Gant chart schedules, with links to Primavera or Microsoft Project Manager, which allows sequences to be quickly changed by drag and drop, with the old and the new side by side for comparison.
To a degree this was being done anyway/ Much of what is now called BIM was previously “collaboration”, or “visualisation”, “3D design” or “virtual modelling”. Now it is called BIM.
But there is more. Firstly, the software and its interaction has reached critical mass, says Autodesk Europe Africa and Middle East region business development manager Adam Mathews. As it does, new capacities spring up, like the use of iPads or other tablet devices on site to fully access the model, tied to GPS location.
Secondly, for leading industry figures and government the transforming effects of the technology are a chance to rework the construction industry, extending collaborative and partnering principles begun in the 1990 around time of the Latham report.
For these purposes there is an even more important element to BIM. That is the passing on of data and information, not just about 3D dimensions and spaces but about the objects from which that a design is made up.
It includes multiple aspects, from specific information about the way something was made and in which factory, or from the precise concrete batch which went into it, to its individual serial number, the address of the maker, details about future maintenance requirements, traffic capacity, wear characteristics and thermal capacity.
This has huge benefits. First the designer’s intent can be passed on to help the construction and more importantly the future operations team. Requests for information can be almost eliminated.
Along the construction process, more data can be captured, such as precise “as built” data. And finally servicing details, specifications and individual component histories are carried right through.
By handing over an electronic “user manual” the operations team has a giant head start. “And massive savings can be made at commissioning stage too,” says Jackson, “which is always an expensive moment”.
Like many others, Mott MacDonald BIM champion Richard Shannon points to the relative costs of design, construction and operation. The savings potential for running buildings or infrastructure as it was intended, is gigantic, making whole life design more important than ever.
Level Two BIM
Currently in so-called Level Two BIM, this information is to be attached to existing 3D models. Level Two is a standard, developed initially in the United States and adapted for the UK. The Construction Operations Building information exchange (COBie), sets out what answers are required to enable compliance to be assessed. This is entered on a standard Excel spread sheet. This can even be filled in manually although automated systems are considered best, and required for Level Two BIM compliance.
But all this is only a beginning, an approximation of “true BIM”, or what the URS Scott Wilson technical director Mark Bew, calls the “Holy Grail”. He should know since he co-chaired the working party that produced the government’s BIM strategy report.
True BIM, or Level 3, will integrate data and physical shape, probably in design “objects”. Instead of drawing volumes, shapes or alignments, and attaching dimensions and linked data, there will be fully parametric self-contained units to make up the model. Each will generate their dimensions and characteristics as required for visualisations and quantities.
The program that first started along that path was Revit, now owned by Autodesk, though ArchiCAD and Bentley Architecture and others also work this way. Much of the design is done by using objects like “windows” which can be selected from a pallet and simply placed.
The object “knows” what it is and how it relates to other objects. The designer specifies dimensions and a component can simply be dropped into place in a wall for example, which will then make the correct space and joints around it. Drag it along and the wall “heals up” and makes a space for it elsewhere.
No longer is the model a 3d design whole but a collection of complex “self-aware” data objects. They relate to each other. They self generate and crucially, contain their own information for later facilities or asset management.
Because they are data units in a relational database, rather than flat files, limits on the size of models are effectively eliminated.
The potential is huge. For example whole components can be predesigned in libraries or even by made available by manufacturers, supplied with specifications and other data, ready to drop in. Some Internet catalogues already do this.
But even Revit has a way to go. And most civil engineering programs have not started this way yet. Clever as they are in calculating cut and fill and generating drawings, and even like Autodesk Civil 3D, at rebuilding the design on the fly when alignments are mouse-dragged, they are still essentially a collection of surfaces with Z coordinates.
“The equivalent in civil engineering would be the capacity to pull in a whole roundabout from a pallet,” says Bew.
Dropping it on a junction point would make see it make the right connections to the roads, calculate the cut and fill and sort out swept paths and traffic impacts.
Object based system
One civils program will soon use objects. Novapoint in Norway has rebuilt its entire road design suite around an object-based system held in a database. Designs are drawn from an online “Quadri Server”.
The system will synchronise with the Norwegian Road Administration which already requires BIM. It is building a complete model of the entire national road system. Designers will be able to check out just the parts they need for a project and check the new design back in, updating the huge model ready for the next project.
It could be the future.