By Vojtech Ernst Gall
BIM is a powerful process that allows owners, engineers, and contractors to better collaborate and to improve the transparency of information shared between partners within a project. Nevertheless, BIM, more so than many other topics, has simultaneously become one of the most used and misunderstood buzzwords in underground construction. This is likely because of a divergence between the outward image of BIM and its inside workings. Non-BIM experts may be more familiar with seeing the products of a BIM process (i.e., 3D models or renderings) whereas BIM professionals are often more focused on the organization and information flow hierarchies (i.e., workflows) within a BIM project framework.
A divergence in opinion of “what BIM is” can already be found in the acronym itself. BIM among BIM professionals (at least in the United States) has almost exclusively become to be defined as “Building Information Modelling,” whereas non-BIM professionals often continue to use the term “Building Information Management.” This issue of definition is further complicated by the often-vague definitions of BIM provided by various national and international organizations. The International Standards Organization (ISO) 19650 series “Organization and digitization of information about buildings and civil engineering works, including building information modelling (BIM) — Information management using building information modelling,” which is commonly used in the tunneling industry, defines BIM as:
“The use of a shared digital representation of a built asset to facilitate design, construction and operation processes to form a reliable basis for decisions.”
The German Tunneling Committee (DAUB), in the much more tunneling-focused document “BIM in Tunnelling,” uses similarly vague language, describing BIM as:
“[A] collaborative method based on digital models for the design, implementation and operation of facilities over their entire life cycle.”
Both definitions make it difficult for non-BIM professionals to immediately understand what BIM is and, in particular, what BIM is in the tunneling and underground domain. Nevertheless, there is a certain necessity to this vagueness. BIM simultaneously describes an information management process, i.e., how information is created and shared within a project and who can access and modify information at which project stages, as well as the models (2D, 3D, or otherwise), their application, and software that are used to do so.
A final issue complicating a unified industry-wide BIM understanding is the level of BIM adoption (or lack thereof) across different projects. A good basis for understanding different levels of BIM adoption is the concept of “BIM Maturity Levels,” introduced in 2011 by the BIM Working Party for the UK government. These levels were introduced to aid in the development of a framework to standardize the level of adoption of BIM across government-funded UK projects. A graphic depicting the BIM Maturity levels is shown in Figure 1. The graphic depicts the different levels of BIM that may be reached in different projects as well as their differences. While the graphic is not US focused, its utility may be immediately recognized. For example, smaller projects without sufficient funding may not include any BIM concepts whatsoever, and therefore reach a BIM maturity level 0. Larger infrastructure projects, in contrast, typically mandate the use of BIM across all parties as well as the delivery of digital assets and are therefore likely closer to a BIM level 2-3. As such, BIM, in its current state, and especially in the US tunneling industry, exists at different levels of maturity across different projects, and therefore also represents different things to different project participants.
BIM, like several other technologies or methods used in the tunneling world, has its origins outside of tunneling. While the concept of BIM has existed in some form or another since the beginning of the use of computers in architecture and engineering (A&E), the true introduction of BIM to the A&E field was in the mid-2000s as software manufacturers, e.g. Autodesk or Bentley, began to focus more on developing BIM-specific software that allowed users to integrate more design information than simply 2D or 3D geometries within models of objects/structures. Although the development of BIM began more so for architectural and building purposes than for tunneling purposes outright, the dates mentioned above also bookend the initial adoptions of BIM in the tunneling industry.
Early adoption of BIM within the tunneling industry often centered around the selection of specific uses of BIM, such as 3D modelling or clash detection, rather than the implementation of a project wide information management framework. Some early projects for which BIM was adopted include the Central Subway project in San Francisco or the Crossrail project in central London, both of which Gall Zeidler Consultants was deeply involved in.
For the Central Subway project, BIM was used extensively for the station design phase during 2008-2010. However, the implementation of the BIM in the station design was limited to the final structures and did not include the construction phasing and sequencing, nor did it require the contractor to implement BIM in its construction planning, thereby creating a missed opportunity for the continued use of BIM in the project. The UK Crossrail project began development of the project wide BIM environment and various other BIM processes in 2008, prior to the 2012 UK government 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 these early projects, the adoption of BIM became more widespread in the industry, especially in countries like the UK in which BIM use was mandated. An example of another project implementing BIM immediately following the success of BIM at Crossrail is the Vauxhall Station Upgrade project, for which Gall Zeidler Consultants provided 3D station design services. Figure 2 presents just such a 3D model of the Vauxhall project used for construction site coordination.
It has become more standard to mandate BIM use for all major national and international tunneling and underground construction projects. To provide some examples, the 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 Gateway Program in New York and New Jersey all specify the use of BIM to some extent. The integration of BIM as a core management concept within these projects, however, varies greatly.
The Gateway program, in which Gall Zeidler Consultants is providing program management support services, only currently specifies the use of BIM as a support tool. Although its use is limited, it still provides powerful benefits, such as clash detection in early design stages, or accurate geolocation of the planned tunnel to as-built structures, as is depicted in Figure 3. This level of BIM adoption for Gateway is in contrast to the HS2 project in the UK (in which Gall Zeidler Consultants is also involved), as HS2 is to a large extent run almost exclusively along BIM principles. All information for the HS2 project is exchanged on a central project database, known as a Common Data Environment (CDE), and design is being performed in 3D. This includes all the added benefits, such as clash detection between disciplines at early design stages, or automatic generation of 3D models, as is depicted in Figure 4. This integration of BIM within a mega tunneling project represents a significant leap forward to what was done in comparable projects just a short time ago.
Regardless of its level of integration, BIM software have advanced to the extent that their benefits can no longer be overlooked. Especially from a contractor’s perspective 3D, 4D (3D + time), and 5D (3D + time + cost) scheduling tools offer significant opportunities to avoid cost and time overruns in a project and thus to ensure profitability. Similarly, using BIM concepts, consultants can provide services to owners that were not possible 20 or even 10 years ago. An example of this is the adoption of BIM as a program and construction management tool in later phases of the close-to-complete East Side Access project in New York City, in which Gall Zeidler Consultants is a major participant and has been involved in the project since its inception in 1999.
BIM software and information management approaches have reached a level of sophistication that allows owners, consultants and contractors to run tunneling and underground projects 100% digitally, from design through construction and finally onto asset management. Nevertheless, certain hurdles still hinder BIM’s full-scale adoption across the industry.
The first, and certainly the most important, is lack of familiarity with BIM. Successful integration of BIM within a project requires all participants readjust their preconceived notions of typical project workflows. 3D design, for example, requires significantly more front-end coordination than 2D design. In a typical 2D design, clashes between disciplines are “weeded out” throughout the design process up to construction. In contrast, 3D design requires all disciplines be coordinated at all design stages. Similarly, 3D models take more setup time than 2D models. Issues such as these also contribute to the perception that implementing a BIM platform will result in higher costs. Although this may be true for the initial set up, successful BIM implementation can reduce overall project costs by achieving savings through the elimination of conflicts, better coordination with project stakeholders, and more efficient construction planning, especially when using 4D and 5D design processes.
Another major hurdle for the adoption of BIM in tunneling is that existing BIM software is not always tunneling-focused. While existing software can be, and is, used successfully in tunneling projects, not all BIM modelling software can, for example, properly model horizontal structures, e.g., tunnels. Similarly, data exchange between software can often lead to difficulties, as tunneling specific file formats are rare.
Both these aforementioned challenges are fortunately being addressed by the industry. To address the lack of familiarity with BIM, the tunneling industry is moving towards a larger degree of standardization across BIM use in projects. The ISO 19650 series, although not tunneling-specific, was published only in 2018, and has now become the standard information management framework in the tunneling industry. Similarly, the DAUB BIM guidelines were only published in 2019 and were followed up with additional material in 2020. To further this trend, the International Tunneling Association (ITA) working group 22 “Information Modelling in Tunnelling,” (of which the author of this article is a contributing member), is currently working on tunnelling-specific guidelines for the adoption of BIM which are intended to be published in mid-2022. These ITA guidelines will hopefully serve as a type of guidebook for owners who are not yet familiar with the core concepts of BIM as it relates to tunneling and therewith further the adoption of BIM in the industry.
Similarly, the lack of specificity in BIM software for tunneling 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 model stationing (chainages), and buildingSMART 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. As more and more projects incorporate BIM, and more and more “digital assets” are created during design, owners are increasingly expecting to use BIM models created during design and construction as asset management tools. The current level of sophistication in software essentially allows for the creation of a “digital twin” of an asset, i.e., a digital representation of an asset which incorporates all the relevant process information needed to maintain and operate the structure.
With the increased trend toward digitization across not just tunneling, 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 tunneling industry becomes more and more BIM knowledgeable “what BIM is” and how BIM is viewed, will also continue to evolve. BIM is a broad topic that encompasses many ideas, concepts, and technologies, and what we in the industry will call BIM in 10 or 20 years (if anything at all) will remain to be seen.
Vojtech Ernst Gall is a Senior Tunneling Engineer at Gall Zeidler Consultants. He has worked on projects ranging from high-overburden rock tunnels to shallow underwater tunnels in soft-soil. Vojtech received his doctorate from the Ruhr-University Bochum for developing numerical models for hybrid reinforced tunnel segments. Vojtech is contributing member of the ITA Working Group 22 “Information Modelling in Tunelling,” chairs the UCA of SME Working Group for BIM in Tunneling, and is also chair of the UCA of SME Young Members.