tunnel: Mr Bettels, in how many projects is Bentley involved? Can you give us an overview?
Lutz Bettels: A precise overview is difficult because our customers do not tell us about every project they are currently working on. But there are a few projects, where we are heavily involved. The best-known example is Crossrail in London, where a large part of the line runs underground. Crossrail is now entering the operating phase and the BIM model, which we created as part of Crossrail, will also be handed over to the operator to become a digital twin.
BIM is indeed an instrument for design and construction; when however a project goes into operation and one wishes to continue to use the model and add additional information – only then does it become a digital twin. Therefore, this is a very interesting phase right now.
An example from Asia would be Singapore, where the underground rail network is also operated with Bentley and the design work is carried out with Bentley products. A third example would be Kuala Lumpur, Malaysia. Similarly to Singapore, we have introduced our design solutions there – specifically Open Rail and Open Site – and the data in the project is administered through our Common Data Environment. In German-speaking countries, our customers working in tunnelling are mostly in Switzerland.
tunnel: Have tunnel designers and operators recognised the necessity of moving from BIM in the direction of digital twins?
Lutz Bettels: Interestingly, this subject has arrived in tunnelling more with designers than with the operators, because they have not thought out how the BIM model can be used in later operations. Many operators don't know what they should actually do with this “thing”. They do not yet know what benefits a digital twin offers.
So it is up to us software producers to present visions of how this data can be used. For this purpose, application cases are being worked on together with operators to explore how a tunnel model can be used during the operating phase. In maintenance planning, for example, if perhaps cracks have opened in the concrete, photos of these cracks can be included into the 3D model. As part of asset management, these can then also be automatically assessed. And if certain events occur or a certain degree of damage is reached, then alarm bells should be ringing and maintenance measures should be initiated. These are scenarios, which we discuss with our customers in tunnelling.
tunnel: What is the difference in the challenge between civil engineering and building construction? Or between tunnelling and building construction?
Lutz Bettels: I see a significant difference between building construction and civil engineering. In fact, civil engineering and tunnelling have another dimension of complication, and that is entire field of geotechnics. In building construction, you produce a ground report in advance, perform the calculations and then you build the house. Especially in tunnelling, geotechnics in the construction phase is a challenge of its own. When excavating a tunnel, you always have to consider: what effects this will have on the surroundings. This also applied for Crossrail in London, where the tunnel was bored in areas with just one metre spacing to an existing tunnel. Therefore simulations by calculation have to be carried out continuously to know: if you do something, what consequences does that have? And then there’s the possibility of changing conditions during the construction phase – for example heavy rain can lead to very soft soil, which in turn can also have an effect on the construction progress.
This is a complexity that you don't have to deal with in building construction. In tunnelling it is necessary to integrate geotechnics into the BIM design. In the overall context of BIM design this leads to quite different potentials, because you can analyse in much more detail in advance what the possible consequences can arise for the project, if the ground conditions change.
tunnel: Is there special software, with which one can integrate this geodata into the BIM system?
Lutz Bettels: First of all, a system is needed, with which geotechnical information can be collected and administered. Bentley has a product called gINT, with which you can document boreholes and link information related to each borehole.
In 2018, Bentley Systems acquired the company Plaxis. This software allows the user to undertake geotechnical analyses – a finite element analysis, where you can first model the ground conditions based on the borehole information. Through a simulation process, one can make statements on how the ground will behave in relation to various construction measures.
We also make these findings available to the BIM designers. In this regard, Bentley Systems announced the acquisition of the British company Keynetix in May 2019. With cloud-based data management from Keynetix, information can be made available to a wider circle of designers and other persons, who use the data.
tunnel: Are there methods of performing subsequent data gathering to produce a BIM model of an existing tunnel, or even convert it into a digital twin?
Lutz Bettels: Yes, this is possible. The first methods, with which I was confronted in this direction, by the way, did not come from tunnelling but from the field of mining, where they had begun to document shafts in the mine with photos. From these photos, 3D models can be produced, which can then be made intelligent. In this way, the entire course of a damage can be documented over time.
tunnel: For example if you take pictures twice a year?
Lutz Bettels: Exactly. Then I can always produce a current picture, and that would then be my digital twin. Digital twin means that I maintain a current image. In a tunnel, this is a bit more difficult, because I have to record a lot. You could however say: it can already serve as a digital twin when it happens twice a year. In this way, changes to the structure can be determined and documented, and the appropriate measures can be introduced.
Even if I don't have a BIM model, if it is still in classic 2D, I can produce a 3D model from photos with Context Capture – a program for reality modelling – where I can save my 2D plan information and make the 3D model intelligent through this annotation. And this can, for example, be linked with maintenance information. Documentation of damage, protocols of inspections etc. – all this data can also be linked with the model. In this way you can create a digital twin for structures, which have long been in operation.