Building information modelling has wide-ranging implications
The digitalisation of the construction industry may be lagging behind sectors such as aviation, energy and the automotive business, but there is no doubt that change is coming, and in many places it has already arrived. Project information systems used in the early stages of design are enabling the creation of 3D virtual prototypes, meaning that infrastructure, buildings and other developments can be simulated and assessed prior to construction using a system known as building information modelling (BIM). The implications of this are wide-ranging.
Where people are seeing and understanding the benefits, it is bringing efficiency into the industry, says Richard Shennan, group BIM champion for UK consultant Mott MacDonald, which is working with BIM on projects all over the world. These include reduced risk for contractors, better visibility of programming, better stakeholder engagement, and it is also enabling people to look at sequencing, particularly around design for manufacture and assembly known as DfMA.
Essentially BIM enables the integration of design information at an early stage, bringing together a multitude of disciplines that have traditionally carried out their work separately. This information can then be updated through the life of the project. For a tower block, for example, the structural design would traditionally be carried out by structural engineers; another team would then undertake design for services, while other designers were engaged on the landscaping and civils design around it. All of this would then come together on site.
By using BIM, the information for all of the designs can be modelled together, giving the entire project team from the client to the contractor a better view of the whole project. Not only can the client see exactly what the project will look like when complete, but the contractor can see how buildable the scheme is, identify and eliminate any potential clashes on site, create a virtual projection of the project sequencing, and therefore optimise the construction methods.
One of the worlds most high-profile examples of the use of BIM is the 224-metre-tall Leadenhall Building in London. The steel-framed, tapering tower is asymmetric, comprised of irregularly shaped elements. This ensures the final geometry of the tower preserves the views of neighbouring St Pauls Cathedral by appearing to lean away from it.
Adding to the complexity of the project was the congested nature of building in central London. But by using BIM, the UK contractor, Laing ORourke, together with the designer, US-based architects Skidmore Owings & Merrill, was able to overcome all of the challenges and cut down the construction schedule. By modelling the structure in minute detail, integrating the architectural, structural and other design aspects and then looking at the construction sequencing in the model, the contractor was able to virtually build the tower multiple times before even starting on site. The unique construction strategy saw 83 per cent of the structure built off site and shaved 6 months off the delivery schedule.
Using radio frequency identification (RFID) software with data tags attached to the physical components, individual elements could be tracked through the manufacturing and installation phases. This RFID technology, when integrated with BIM, can be used to update the model with real time information about the new building.
Its name suggests BIM is only for buildings, but it is being used on all manner of infrastructure. Mott MacDonalds Shennan points to the expansion of the light rail network in the Norwegian city of Bergen as a leading global example of the benefits BIM can bring. Working for client Bybanen Utbygging, a division of the city council, Mott MacDonald used BIM as a project management tool throughout the design and construction phases. One thing we did very effectively was to capture all the terrain data and integrate all of the disciplines involved, says Shennan.
The route of the new 7.5-kilometre light rail line involved a multitude of tunnels and bridges, as well as drainage, overhead power lines, communication systems and the track itself. Designers working on the project in seven countries worldwide were able to access the same information, using Bentley Projectwise software to view it.
The BIM model was then used to inform the construction machinery that would create the new railway line, from tunnelling machines to excavators. We are communicating information from model to site-based, GPS-enabled plant because the model is geo-located and modelled onto the existing terrain data sources, says Shennan.
At the same time, the model was used to enable trenches to be dug for the installation of services that traditionally would have been carried out by different utility contractors at different times, and would have involved repetition of work.
Another light rail scheme that used BIM was the construction of the record-breaking Al-Mashaaer al-Mugadassah Metro in Mecca. The 18km line was designed, built and operational in just 21 months, opening in time for the Hajj of 2010. The scheme was built by China Railways Construction Corporation (CRCC), and the systems consultant, mechanical, engineering and plumbing (MEP) designer, and civils work verification consultant was the UKs Atkins.
Regional rail director Julian Hill says BIM was critical in enabling the project to meet the tight timescale. At the time, BIM was relatively new. We had used it on the Green Line of the Dubai Metro, so we had the capability to take it forwards onto the Al-Mashaaer Metro, he says. All the design information from all of the parties was entered into the model to ensure the plans were integrated and buildable.
[BIM] was used as a construction tool to coordinate and integrate the designs and prevent any clashes on site. It enabled the contractor to have more certainty on the programme, which was extremely aggressive.
One of the features of BIM is that traditional construction drawings can be derived from the model. You can cut it and produce a 2D drawing anywhere throughout the section. So CRCC used the 3D model to show that it was fully integrated between the disciplines and they literally built from that. It really saved a lot of time, and onsite you have no clashes in architecture, structures or MEP, says Hill. All the work we are doing on other metros in the region is using BIM, and clients understand that it is a lot better and are now requiring it in their specifications. You can now link the models to construction programmes and watch them being built, he says.
Shennan observes that at the moment it is more common for drawings, specifications and schedules, known as construction deliverables, to be extracted from the design model and then given to the contractor, but this is changing as contractors embrace BIM. We are already moving on and we are now starting to exchange the geometric information inside BIM models with contractors because often they have to add more detail to the same environment, he says.
Populating the model itself also raises a number of issues around software and manufacturer data. Not all suppliers have data in a BIM compatible format and software developers themselves are only just starting to embrace the idea of interoperability.
Initially, software providers made it hard to share, but now they realise people need to move information easily so the drive is interoperability, which is key to a more efficient overall process in building design, says Shennan.
From the manufacturers perspective, the digital BIM model requires data about each component that is being used on the project. A model is made of hundreds or thousands of objects containing information, says building materials firm Lafarge Egypt in a briefing document on BIM. A window contains not only information related to all possible sizes, but also its weight, colours, materials, contact details, standards, thermal performance values, and so on.
From the early stages of a project, when creating an outline design, a consultant or architect would start with generic objects that determine overall performance, such as general spatial awareness. This can then be updated by the designer or contractor with more specific details about these components as the scheme progresses.
Manufacturers out there are creating BIM objects of all their products (and some are quite advanced), investing heavily in building objects that can be downloaded into your model. These objects tend to be specific and data-heavy, suitable for the final stages of a project information model, says Shennan.
The idea of having an as-built model containing all of the project-specific information that an asset owner could ever require is the next step for BIM. The biggest beneficiary is the asset owner because the BIM model provides so much information about the asset that they can use it to optimise performance and value. However, some asset owners may need to look at organisational change themselves in order to gain the full benefit of organised information.
For the Middle East and North Africa, there is much to be gained from encouraging and supporting the use of BIM. It reduces exposure to time on site, makes programmes more efficient, reduces risk, and makes projects safer and more cost effective. Furthermore, in an environment where cost is king, the value engineering exercise, which is almost universally carried out at the end of the design phase, can be done sooner. It also enables value engineering to be carried out live as the project progresses, rather than out of sequence, when it doesnt always deliver the best overall value, says Shennan.
With so many advantages, the biggest surprise about BIM is that it has taken so long to catch on as other sectors have left construction behind in terms of digital development. But with countries including the UK mandating its use on public projects, the digital revolution is gaining ground globally, and the biggest beneficiaries both for construction and long-term maintenance are the clients that choose to use it.
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