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Keeping up to date with tunnelling best practices – event report

9th, December 2024

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Conquip exhibited and sponsored at the popular, annual New Civil Engineer Tunnelling conference for the first time. Here’s our report…

Decarbonising tunnelling

The first panel of the day featured Arup, National Grid, Inbye Engineering and Mott McDonald, with senior leaders discussing a number of current topics. There was broad agreement that it is critical to look at how to reduce emissions in the design of a scheme, specification criteria as well as the selection of materials and how sustainable those all are can contribute to reductions.

Carbon reduction targets, set by the client, provide a framework for design and build contractors, so the onus is on industry and materials producers to increasingly close the price gap between sometimes more expensive low carbon materials towards the cost of high carbon materials.  Concrete has an 80% carbon footprint and this is the material that has the biggest contribution to tunnelling structures. It has challenges around durability and temperature fluctuations, so new materials are welcome if they can perform, when tested to the right standards and factors of safety.

The group agreed that value engineering is about improving functionality, environmental benefit and reducing cost.

Major projects

We listened to a fascinating presentation from SSE about the Coire Glass hydro pumped project in Scotland. The project spans the biggest geological fault line in the UK, so their exploratory ground investigation works project to understand the ground makeup has been key. Led by contractor Strabag UK, this part of the energy infrastructure project took 20 months, ahead of 11 km of tunnelling due in the main works.

We also listened to a status update on the Lower Thames Crossing project from one of the new main contractors, who has just been appointed by National Highways. The Bouygues TP-Murphy JV presented, with Balfour Beatty and Skanska also on board for other packages of work.

This upcoming transport project will act as a key link from the Channel heading to the South East, going on to facilitate easier movements to the north of England. Right now, the main contractors are focusing on a method-led approach, with additional ground investigation, buildability and sustainability the priorities. One 4.25km long tunnel boring machine will be used from the north, to the south and then to the north again, which should keep the project to time and reduce carbon emissions.

Conquip featured in the conference programme

George Critchley, Group Director at Conquip and Robbie McGoran, Head of Work Winning and Business Development at Joseph Gallagher hosted a roundtable entitled ‘Optimising site management and muck away’.

The purpose of the session was to discuss challenges around site management and the efficient removal of muck – both critical aspects of tunnelling projects, with major implications around risk, safety and cost control. Attendees discussed how to select the best methods, reduce environmental impacts, minimise disruption for local communities and options for when space is restricted and when spoil types change in classification over the duration of the project.

Robbie started off with: “We’re looking for productivity, safety and innovation. The equipment must fit into the chosen methodology, how it improves behaviour health and safety, reducing accidents by removing the human element and people-plant interfaces. Closely followed by the environment. We need Project Managers and Construction Managers working together to achieve volume removal with the right technology in the programme for each project.”

George said: “When sites and engineers are open-minded to new technologies, they can improve efficiencies into how things are done. We are seeing that shift in earlier engagement and better ways of doing things.  This is the story of the Crossrail project at the Stepney Green site and how our bulk excavation solution, BulkX was born, compared against the legacy older skips – the development of the BulkX ticked boxes on improving production rates and reduced the dig time by 12 weeks. If you get in early enough in the tendering stage, a change in method can have a dramatic improvement on efficiency rates.”

Robbie agreed, saying: “Space and clash detection is key, the logistics and lifting plans need to be suitable for the programme. On all our projects we need to reduce double handling, reduce muck cycle times and volume of trucks coming in and out of site, especially on tunnelling projects when there are such variations of soil types, conditions and changes to both of those variables as water is either added or removed from soil.”

The group discussed a variety of issues around not only handling soil and muck in all its forms but whether there is space for processing or treating it on site or off-site, bringing the discussion back around to the importance of the right methods at each stage of the project and how to manage the huge challenges of site logistics.

It was definitely food for thought, as one attendee pointed out that there will be a significant need to identify efficient muck away for the lifetime of the Sizewell C nuclear plant – it’s estimated that 10 million cubes tonnes of muck will need to be removed, some of which will come from the tunnels and shafts needed to cool the nuclear reactors.

The last panel session covered how infrastructure decision-makers can better manage upcoming project pipelines, with J Murphy & Sons, AtkinsRealis, Jacobs and TfL part of the discussion. We took away that funding and stability are key to project management and achieving realistic project costs, both for total and annualised costs.

Interested to work with Conquip on tunnelling projects? Contact us at sales@cqegroup.com.