Construction of a 14,500-tonne box structure designed to take the new HS2 line under the A46 Kenilworth Bypass in Warwickshire has taken a major step forward, following the successful installation of 120 gigantic beams.
The concrete beams, ranging between 13 metres and 24 metres in length, were carefully lifted into place using three giant cranes to form an integral part of the structure’s top. A dedicated team of engineers worked round the clock to successfully complete the entire operation ahead of schedule in just 14 days.
Due for completion later this year, the huge box is currently being built on land next to a section of the A46 rather than constructing it beneath the carriageway itself – avoiding the need for up to two years of traffic management measures.
With the beams now in place on top of the box, the finishing touches include completing the deck – the flat surface placed on top of the beams – and installing parapets. In spring, the completed structure will be moved into position under the existing carriageway using an innovative technique.
This will involve a jacking mechanism, designed by specialist civil and structural engineering company Freyssinet, which will push the box across on a guiding raft at a speed of up to 2.5 metres per hour for a total distance of 64 metres.
Together with National Highways and its construction partner for the West Midlands, Balfour Beatty VINCI (BBV), HS2 has started preparing for the box push procedure.
A section of the A46 between Festival Island (Coventry) and Thickthorn Island (Kenilworth) will be closed for two weekends next month for the first stage of preparation work – with plans to move the structure into position during a full closure of the A46 Kenilworth Bypass in spring 2025 for up to three weeks.
During the two weekend closures, from 8pm on 7 February to 6am on 10 February and from 8pm on 14 February to 6am on 17 February, HS2 engineers will upgrade road safety barriers, adjust the layout of the central reservation and complete advance drainage works under the carriageway.
Vicki Lee, Senior Project Manager for HS2 Ltd, said:
“I’d like to congratulate the entire site team for successfully moving such a large number of beams into place and as we approach the final phase of the A46 box’s construction.
“I also thank motorists in advance for their patience as we prepare for the box push in spring and start our initial stage of preparation work during two February weekend closures of the road. This will allow us to carry out important work directly on the carriageway that would be unsafe for our workforce to do during live traffic.”
At peak, a workforce of 130 people will be based on this structure, delivered by HS2’s construction partner BBV.
John McNiffe, Project Director at Balfour Beatty VINCI, said:
“The safe and successful installation of 120 giant beams is another great achievement for the Balfour Beatty VINCI team who are delivering this box bridge slide in Warwickshire. This 14-day operation required huge amounts of planning and precision and I’m really proud of the way they’ve responded to this challenge.
“The next stage includes construction of the deck and installation of the bridge parapets before the bridge can be moved into position under the existing carriageway, allowing HS2 trains to pass underneath.”
David Patmore, Network Planner for National Highways, said:
“Our primary concern is that works on our network cause minimum disruption for road users while still ensuring the safety of both the workforce and those using our roads.
“We work very closely with HS2 and its partners and welcome the innovative techniques being used to meet that objective and reduce the impact that such a major, complex project could have on the travelling public.
“It is good news that the works are progressing so well and we are grateful for drivers’ patience as the scheme moves towards the box push in the spring.”
The structural design has been carried out by Balfour Beatty VINCI’s Design Joint Venture, made up of Mott MacDonald and SYSTRA (MMSDJV).
Tim Akers, Engineering Manager for the Mott MacDonald SYSTRA Design Joint Venture, said:
"We're incredibly proud of the part we've played in the development of this structure. Through significant collaboration between HS2, National Highways and Balfour Beatty VINCI, the design has been reviewed and changed from a traditional ‘top down’ approach to an offline construction method with automated rapid and safe installation, reducing the impact to road users significantly.”
Local residents looking to find out more about the A46 works and HS2 activity in the area can attend a community drop-in event being held on Wednesday 15 January, from 2pm to 7pm, at the Kenilworth Centre, CV8 1QJ. Further details can be found at www.hs2.org.uk/events or by contacting the HS2 Helpdesk on 08081 434 434 or HS2enquiries@hs2.org.uk
Construction of HS2 continues at pace between the West Midlands and London, with the programme now supporting over 31,000 jobs. When complete, HS2 services will run between London and the West Midlands on a dedicated high-speed line before reaching destinations further north via the existing West Coast Main Line.
In recent weeks, construction progress in the West Midlands has seen HS2 complete the first stage of work for the construction of a bridge that will take the high-speed railway line over the M42 motorway. Two 159-metre-long steel spans of HS2’s River Cole Viaducts have also been completed near Coleshill in North Warwickshire, signalling further progress at the project’s Delta Junction.
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