TECHNICAL | BUILDING INFORMATION MODELLING
mandate that required BIM processes to be
implemented for all government funded mega projects. The use of BIM on Crossrail for construction planning was instrumental in addressing construction challenges and implementing resolutions. Due to the success of BIM in early projects such
as the above, the adoption of BIM has become more widespread in the industry, especially in countries like the UK in which BIM has been mandated for state-funded projects. An example of another project implementing BIM immediately following Crossrail is the Vauxhall Station Upgrade project, also in London, for which Gall Zeidler Consultants provided 3D station design services.
CURRENT USE By now, it has become more standard to require BIM used on major national and international tunnelling and underground construction projects. Examples of its use include: Ontario Line Subway, in Toronto, Canada; the HS2 project, in the UK; the Grand Paris Metro, in France; the Brenner Base Tunnel between Austria and Italy; and, the BART Silicon Valley Phase II Extension project in the US. While these projects specify the use of BIM to some extent, its integration as a core management concept varies greatly. One of the most successful implementations of
BIM in tunnelling is for the HS2 project, in which Gall Zeidler Consultants has developed several designs. In HS2, all information is exchanged on a central project database, known as a Common Data Environment (CDE), and design is being performed in object-oriented 3D models. This includes all the added benefits, such as clash detection between disciplines at early design stages, or automatic generation of 3D models. This integration of BIM within a mega tunnelling project represents a significant leap forward to what was done in comparable projects just a short time ago.
FUTURE OUTLOOK Regardless of its level of integration, software for BIM has advanced to the extent that the benefits it offers can no longer be overlooked. BIM software and information management approaches have reached a level of sophistication that allows owners, consultants, and contractors to run tunnelling and underground projects entirely digitally, from design through construction and finally onto asset management. Nevertheless, certain hurdles still hinder BIM’s full-
scale adoption across the tunnelling industry. The first hurdle, and certainly the most important, is
lack of familiarity with BIM. Successful integration of BIM within a project requires all participants to address pre- conceived notions of typical project workflows. For example, 3D design requires significantly more
front-end coordination than 2D design where clashes between disciplines are ‘weeded out’ throughout the design process, all the way up to construction. In contrast, 3D design requires all disciplines be coordinated at all design stages.
18 | June 2023
Similarly, 3D models take more setup time than 2D
models. Issues such as these contribute to the perception
that implementing a BIM platform will result in higher costs. Although this may be true for the initial set up, successfully implementing BIM can reduce overall project costs – achieving savings by eliminating conflicts and expensive corrections during construction, achieving better coordination with stakeholders, and enabling more efficient construction planning, especially when using 4D and 5D design processes. Another major hurdle is that existing BIM software is
not always tunnelling-focused. While existing software can be, and is, used successfully in underground projects, not all BIM modelling software can, for example, properly model linear structures along curved alignments, e.g., tunnels. Similarly, data exchange between different software packages can often lead to difficulties, as tunnelling-specific file formats are rare. While the industry tackles these hurdles, it is also
addressing the lack of familiarity with BIM by moving towards a larger degree of standardisation for use of BIM in tunnel projects. The ISO 19650 series, although not tunnelling-specific, was published in 2018 and has become the standard information management framework in the industry. Similarly, DAUB’s guidelines were only published in 2019 and were followed up with additional material. The International Tunnelling Association’s (ITA)
Working Group 22, Information Modelling in Tunnelling, (of which a co-author of this article is a contributing member), has developed its first tunnelling-specific guidelines for the adoption of BIM, focused on bored tunnelling. Similarly, the lack of specificity in BIM software for
tunnelling projects is being addressed by the industry as well as by the software developers. Newer versions of modelling software are increasingly incorporating the ability to properly model stationing (chainages), and building SMART is developing tunnel-specific non- proprietary file formats under the IFC-Tunnel project to better exchange data between different software packages. Another major shift in the industry is coming in the
form of adopting BIM for Asset Management purposes, with more owners expecting to use ‘digital assets’ for post-construction phase decision-making and control. This becomes a ‘digital twin’ of the asset, especially if, post-construction, the model gets updated with ongoing information flows relevant to support better maintenance and operation of the structure in service. BIM is a broad topic. It encompasses many ideas,
concepts, and technologies. With the increased trend toward digitisation across not just tunnelling, but all industries, BIM concepts will almost certainly become engrained in many, if not all, tunnelling projects sooner rather than later. Concurrently, as software continue to progress, and as the tunnelling industry becomes more knowledgeable, how BIM is viewed and used will continue to evolve.
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