The A46 Kenilworth Bypass has reopened 18 days early after HS2 engineers slid a 14,500-tonne box structure into place, marking the UK’s heaviest bridge slide
After entering the final phase of construction in January, the structure will allow HS2 trains to travel beneath the road of the bypass.
The structure was pre-built onsite
With an estimated two years required to build the box structure using traditional methods, the structure was built beside the A46 Kenilworth Bypass to be slid into position afterwards.
This structure is the heaviest of its kind throughout Europe, and just one of over 200 new bridges and viaducts for the HS2 railway.
The box structure was designed as such to allow easier installation and construction given the location, and avoiding unnecessary delays, speed restrictions, and lane closures. The operation was performed in three parts and was led by Balfour Beatty VINCI JV, timed to take advantage of less traffic during the Easter break.
The first stage saw demolition of a 200m-long section of old road, followed by the excavation of 35,000 cubic metres to create an area for where the box structure will be pushed into place. The material excavated was recycled later.
The second stage saw the 42m-wide structure pushed into position over 10 hours. This was achieved through a jacking mechanism, known as Autoripage. Autoripage involved 15 jacks that guided the box and allowed adjustments to be made during travelling. The box was pushed at an average speed of 6.5 metres per hour across 64 metres.
The final stage saw reconstruction of the embankments, with a new carriageway built and reopened to traffic at midnight of 30 April. One lane remains closed on either side of the road until Thursday 31 July to allow for construction of central reservations and wingwalls.
“The vast majority of the bridge is now complete”
Cameron Thompson, HS2 Ltd’s head of delivery, said: “It’s amazing to see the A46 box in position and I’d like to thank everyone who’s worked so hard to get the road open early. This record-breaking slide could not have been achieved without the years of meticulous planning and preparation that the team put in, working closely with our supply chain and National Highways.
“While the vast majority of the bridge is now complete, we’ve still got a few weeks’ of lane closures to finish the central reservation and wingwalls – and I’d like to thank drivers in advance for their patience during these works.”
Victoria Lazenby, National Highways regional director, said: “Our concern with any scheme is to minimise the impact for people using or living near our roads and certainly such a huge, complex engineering feat as this would inevitably bring some disruption.
“So to have avoided two years of lane closures and speed restrictions on one of our key routes is tremendous news. After many years working closely with HS2 and their supply chain we are delighted to see all of that planning and preparation come to fruition.
“We are grateful to people for their patience during the road closure to enable this innovative work to take place.”
John McNiffe, project director at Balfour Beatty VINCI, said: “We’re extremely proud to have successfully delivered the UK’s heaviest bridge slide across the A46 in Warwickshire. It’s a huge achievement for the dedicated project team who’ve worked tirelessly over the last two years to reach this point.
“My team has worked around the clock, using innovative construction methods to move this bridge into place and return the road back to normal in just 18 days, reducing the impact on road users significantly.”
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