Cementation was appointed by the Skanska Costain STRABAG joint venture (SCS JV) to create one of the largest open-cut retaining boxes in Europe for HS2 – equivalent in size to four football pitches.
The site which stretches for almost a kilometre was to house the lines coming into Euston Station. Known as Euston Approaches, the project involved the installation of almost 2,000 rotary bored piles over five assets on the London tunnels section of HS2. The five packages were:
- nearly 800 piles to create the Euston scissor box (ESB) to carry the new running lines
- over 600 piles for two new bridge structures – Hampstead Road Bridge (HRB) and Granby Terrace Bridge (GTB) – to take traffic over the new lines
- 343 piles for an extension to the scissor box known as Euston throat retained cut (ETRC)
- 134 piles for the new Euston cavern shaft (ECS).
In all, the completed project will comprise a total of 1,831 piles and an estimated 18,000 cubic metres of concrete and 120,000 tonnes of steel.
Project expertise
From the outset Cementation brought together specialist teams and in-house capability to help deliver a one stop solution and reduce the carbon footprint of the piling works. These included:
- Our inhouse design, technical and carbon reduction specialists.
- Our steel fabrications facility for the manufacture of nearly 100* bespoke plunge columns.
- Our unique, high capacity, pile load testing system, designed and built in house and operated by own expert field data acquisition (FDA) monitoring experts.
Following direction from the Government to pause some HS2 work, progress on the project stopped temporarily in June 2023 with an expected restart date around April 2025.
By the time the work paused, more than 65% of the overall project was complete and we’d already brought several award-winning innovations and new carbon saving techniques to the industry.
Innovation and carbon reduction
Examples of the forward-thinking innovations and carbon reduction measures we’ve brought to the project include:
MLT60, the highest capacity ‘portable’ load test system in the UK
In 2022, our new 60 MN maintained load test system (MLT60) came to the site, where it added significant capability in pile load testing. The MLT60 is capable of testing up to 60 MN (or 6,000 tonnes). With data capture capabilities and instrumentation built in it can monitor how the ground is behaving and where forces are going up to the point of failure on greater loads than ever before.
Already a leader in the sector, the new test system coupled with our piling installation and in-house field data experts means our pile testing and monitoring capability is second to none.
Bringing green fuel alternatives to heavy construction equipment
After a successful trial using hydrotreated vegetable oil (HVO) on a piling rig, we converted our whole plant fleet to HVO fuel. This was part of Skanska UK’s company wide commitment to using HVO to power all site plant and equipment on every project. This move away from diesel has enabled Euston Approaches to be a diesel free site since March 2022.
Although the shift to HVO has already saved 387 tonnes of carbon over the course of this project, our ambition is to move to hydrogen or electrification for construction plant as soon as technology allows. That’s why we used this project for two further trials that took place in early 2023:
- In April, we joined forces with Bauer to bring the world’s first plug-in, electric high-capacity drilling rig to work on HS2. The rig uses a powerful electric drive to replace the diesel engine. By plugging it into an electric sub-station installed on site, we could run it without any need for diesel powered back up. This meant we could eliminate exhaust CO2 emissions and reduce the local noise impact on residents.
- The following month we pioneered the first real world use of a hydrogen dual-fuel piling rig. Following successful trials with ULEMCo and Building Research Establishment (BRE) backed by Government funding, we brought the dual-fuel rig to install four piles to a depth of 30 metres.
In initial trials, the rig, modified to operate from on-board hydrogen tanks, had achieved 36% (average) displacement of fuel (diesel or HVO) by hydrogen, corresponding to the equivalent reduction in fuel consumption and CO2
These trials are a major step forward for piling, ground engineering and beyond. They pave the way to construction site decarbonisation by proving the potential for fuelling other types of heavy plant with hydrogen dual-fuel or all-electric.
Zero trim piling
The zero trim piling technique, developed with Hercules Site Services and SCS JV, is another transformational breakthrough for the whole industry.
Traditionally, concrete is overpoured in piles then site teams manually break out the excess concrete. This method can cause hand-arm vibration syndrome, hearing loss and silicosis. The new ‘zero trim’ approach uses a vacuum excavator to suck out the excess while it’s still wet, creating a safer method for workers.
Further benefits of the new technique include cost and environmental savings due to reduced concrete volumes and less construction noise for local neighbourhoods. So far on this project the use of zero trim piling has saved 496 tonnes of carbon.
Low carbon concrete
Working with Hanson, we developed a 79% cement replacement mix for use in permanent piling works. Approved for use, and introduced to the project in January 2023, the new mix has the potential to deliver carbon savings of 45% CO2e. By the end of the project, we expect to deliver a saving of 4,600 tonnes CO2e on the estimated 40,000m3 of concrete required from January 2023 onwards.
Low carbon guidewall
Following a Skanska led trial on the M42 Junction 6 project, Cementation worked with supply chain partners to adapt basalt technologies for a guidewall system.
Developed in collaboration with the SCS JV, Basalt Technologies, Hansons and L&A Reinforcements Ltd, the solution replaces conventional steel and concrete with basalt reinforcement and low carbon concrete.
Believed to be a UK first, the new guidewall system led to a reduction in embodied carbon of more than fifty per cent – over and above the low carbon concrete mix already in use on this project.
Outcomes
So far, work on this project has progressed successfully on track in terms of both time and budget. As with all our projects, safety has been paramount, particularly with some of the works happening within six metres of the West Coast main line.
However, what we are most proud of is the incredible contribution the teams working on this project have made to the wider industry in terms of innovation and carbon reduction.
This remarkable contribution has been evidenced by the multiple awards achieved, including:
- BCIA health and safety award 2021 - zero trim piling
- FPS sustainability award 2021 – zero trim piling
- CN specialist innovation of the year 2021 – zero trim piling
- FPS carbon reduction award 2022 – low carbon guidewall
- GE editors award 2022 – zero trim piling.
*all data correct as of June 2023
