Data-led digital value creation in HS2

Elena Solja: Hi Paul, it’s a pleasure to see you again. We’ve been working together on optimising sprayed concrete usage in the construction of HS2 London tunnels for some time now. What makes this process so important and relevant to you? 

Paul Challinor: Hi Elena, likewise. On our joint project, Sprayed Concrete Utilisation, we have been working with Normet since around November 2023. Ross Dimmock [Normet Vice President, Tunnelling] and I have known each other for many years - I would say it must be around 18 years since we met at the bottom of a dusty shaft under construction - and one of our frequent topics of conversation when our paths cross is how to make the sprayed concrete tunnelling process less wasteful.  

It is a problem that the industry in general has accepted and almost ignores as it is seen as difficult or impossible to improve. However, this pessimism is something that I am unwilling to accept, and we have supported various initiatives to improve sustainability. 

ES: Concrete spraying, including all its elements such as blasting, transportation, batching and so on, is certainly an area where improvements can be made. At Normet we have been developing new methods within this process for many years with an eye on improving efficiency, safety and sustainability. Today’s digital technology gives us new opportunities for this. When I joined Normet almost two years ago, after a background in creating digital twins for cities, it quickly became clear that the same technology can be efficiently used for mining and tunnelling processes. 

PC: That’s right. Normet are one of strategic supply chain members, supplying us with construction chemicals for the sprayed concrete process, predominantly in partnership with our pre-blended sprayed concrete supplier. But we frequently turn to Normet for their technical expertise and support for challenging situations such as when we have specific mix requirements or are doing something niche like spraying on artificially frozen ground. 

Normet’s digital team has been very helpful in collecting and analysing data as we do not have those capabilities in-house. When we started cooperating with Normet, we began by establishing where in the process waste occurs. This was an eye-opening moment as everyone in the room had wildly different ideas of what the wastage value should be, and how this was apportioned throughout the various stages in the process, from batching on site to spraying in the tunnel.  

ES: Data gives flexibility and power. We like to say, “What we can measure, we can manage.” With data we can fully understand what happens in our processes and control it. Part of Normet’s aim here was to show the value that collected data can have. In the case of concrete spraying, this data included what kind of concrete is used, how much accelerator, filling ratios, machine behaviour, strength values, thickness, and so on.  

In Finland, Remion's analytics team compiled the data to create 3D models. Once the data was processed and the 3D digital twin models were completed, we were able to pinpoint with reasonable accuracy the areas where concrete waste was occurring. 

PC: Revealing where the high waste points in the process are really led to a greater understanding of the issues and allowed us to develop plans to tackle each stage. I cannot overstate how revolutionary the outcome of this was.  

As I previously mentioned the Sprayed Concrete Tunnelling is inherently wasteful, and on a project the size of HS2 S1 and S2 the cost and carbon impact of this waste have been significant. At Euston SCL Approach Tunnels we wanted to try to make a difference. We will be spraying ~44,000 cubic metres of concrete to construct approximately 1.5km of tunnels. Only around 18,000 cubic metres will remain as part of the permanent works, meaning over 26,000 cubic metres is wasted in some way as part of the process. That is equivalent to some 11.7 million tons of CO₂ emissions and several million pounds of financial investment. We wanted to change that. 

ES: That is a significant potential saving and really shows the value creation possibility of data analysis. Identifying where the losses are greatest, for example in over-ordering, overspray or rebound also gives rise to other benefits in addition to a significant reduction in concrete material requirements. Associated benefits include faster operations, improved safety, and a greater degree of operational transparency.  

PC: Exactly. And we are already looking at the next stage of this initiative. As Normet is our key supplier for underground spraying equipment, we hope to incorporate laser scanning equipment into the machines in combination with Normet’s existing IoT technology package to continue to tackle each of the waste points in the process. 

ES: This is really something that we are actively researching. How we can incorporate different Normet digital technologies in relation to different underground processes to create a holistic network where data is gathered, analysed and used to improve efficiency throughout? Working with you on the HS2 project has vividly demonstrated the potential for these methods. 

PC: I agree, and we look forward to continuing to work with you in the future. 

STRABAG is a global construction company headquartered in Vienna, Austria. 

Remion is a specialist industrial digitalization and internet company based in Tampere, Finland. The company was acquired by Normet in 2023.