DATA, DIGITAL & BIM | INSIGHT


The four appendices are:


A. BIM use cases B. Level of information need: bored tunnels C. Level of information need: conventional tunnels D. Level of information need: ground model


Section 2 – on Terminology & glossary – discusses


the ISO 19650 series of international standards that cover BIM “and continues to evolve quickly”. To underpin the importance of the series, the guide says: “ISO definitions take precedence over all others.” Still, confusion can arise in application and use in industry, and so the guide devotes some discussion to the series, definitions and clarifications. For example, what is EIR? If you think the acronym


can only mean ‘Employers Information Requirements’ then confusion would likely arise when adopting BIM, for in its realm, in general terms, the shorthand equates to ‘Exchange Information Requirements’. Yet both can be in a project – the former referring to contractually obligated BIM requirements on a tunnel (or other infrastructure) project while the latter is wider (yet relates to managerial, commercial and technical aspects of producing Project Information). Watch out for temptation to quickly scan the guide, for


upon seeing EIR it may not mean what you think. Additionally, while the ISO 19650 series uses the term


‘Client’ rather than ‘Employer’ – i.e., the Owner or Sponsor of a project, typically (though not always) – the guide doesn’t follow this wording. “In this document the term Employer is used,” it says, and notes in the definitions that Employer additionally means, ultimately, the ultimate initiator of the need to implement BIM on the project; that could be the top-level Owner or a main contractor, for example. So, again, being clear on the terms is vital.


GROUND MODELLING The guide points out that inclusion of ground information into a BIM model is “not always specified” despite such being “a vital component” for tunnel projects. More than simple inclusion, the guide says such information “should be continuously updated”, giving the longer-term benefit to the project Owner/Sponsor of having a developed baseline for future infrastructure plans. It further notes that an aspect of the difficulty


of inclusion of the ground information is the sheer volume of data required for “full representation”. It adds that much of the ground information “requires some specialist interpretation”. Information types and formats are recommended


and so also are ways to integrate the ground model with ‘traditional’ BIM objects, and when to present such within the project life cycle. Ground information in BIM environments also often has different data structures to those for structural or architectural data, the guide says. Commonly, therefore, such data is kept separate from the main tunnel BIM model – which also helps to reduce computation and storage size and load. Various sub-models, matched to project needs and stages, can hold different data.


“Integration of any ground information in BIM


should be for the purpose of added value, not added complexity,” it says. Integration of the ground model into contractual risk-


sharing is also discussed – and that countries differ in their practices, which “may or may not distinguish between factual data and interpreted data”. Geotechnical Baseline Reports (GBRs) are also discussed in this context. This brings back the point of interpretation. The guide


refers to interpreted data as “non-factual” and says its inclusion “may impact risk-sharing arrangements” during negotiations. As such, clear identification of such data and what uncertainties there are in interpretation need to be weighed, quantified and spelled out. Methodologies vary for doing so, however, and are Owner/Sponsor dependent, the guide adds. It further notes that, while recommending for the


inclusion of updated data as the project evolves, the needs of contractual arrangements early on, and thus risk-sharing in procurement, plus having “a basis for settling disputes”, require a version of modelled data to be locked-in earlier. This would be determined by the Owner/Sponsor.


The full guide was published previously in a special issue entitled ‘ITA-AITES Reports’ in Tunneling and Underground Space Technology (TUST), from Elsevier, in 2025, on an open access basis under a Creative Commons licence (CC BY - http:// creativecommons.org/licenses/by/4.0/). It is available in full there, at https://doi.org/10.1016/j.tust.2025.106714, as well as the ITA-AITES website. WG 22 is the Working Group focused on ‘Information Modelling in Tunnelling’.


September 2026 | 39 Above top:


Figure 1 in the report. Hierarchy of information requirements as excerpted from ISO 19650–1 (ISO, 2020a).


Above bottom:


Figure 6 in the report. As-built Tunnel Model for a Bored Tunnel including exact as-built ring segmentation details.


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