Final concrete pour on Mersey Gateway's south approach viaduct

20 June 2017

MSS Webster, the giant bridge building machine has completed its final concrete pour on the Mersey Gateway’s south approach viaduct.

The Mersey Gateway bride under construction 2016. Photo: David Hunter, courtesy of Merseylink

The Mersey Gateway bride under construction 2016. Photo: David Hunter, courtesy of Merseylink

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The 1,700 tonne machine, which looks and operates like a giant Meccano set, has been working on the south approach viaduct for around 10 months, slowly creating the reinforced concrete deck that will be used by 60,000 vehicles per day.

Webster is one of two Movable Scaffolding Systems (MSS), specially designed and built to construct the curved viaducts leading to the Mersey Gateway Bridge, the centrepiece of the iconic project.

The final pour was a 28-hour operation – 1,133 cubic metres of concrete was being poured into the giant mould to complete the deck of the south approach viaduct.

It has now been moved back one span and will slowly be dismantled over the next couple of months before being transported to Bratislava to join its fellow MSS Trinity, which is helping to build a new bridge over the River Danube.

Webster is 157m long and 8m high. It is 22m across at its widest point and weighs 1,700 tonnes.

In total since it started work MSS Webster has constructed eight spans of the south approach viaduct using 9,205 cubic metres of concrete, equivalent to filling four Olympic-sized swimming pools.

The massive machine has acted as a giant concrete mould, known as ‘formwork’, and needed to be assembled piece by piece, It was initially lifted into place with two giant cranes, one weighing 700 tonnes and one weighing 750 tonnes.

Hugh O’Connor, General Manager for Merseylink, said: “To have reached this landmark just 10 months after building Webster is great news for the project.

“The viaducts on either side of the river are huge structures in themselves, with the south approach viaduct requiring a considerable degree of engineering and construction skill to build, as well as using a huge amount of material. This final pour on the south approach viaduct means we’re getting closer and closer to completing this iconic bridge.”

Cllr Rob Polhill, Leader of Halton Borough Council, said:

“The work taking place on the estuary is truly remarkable and it is an absolute delight to be able to see such engineering marvels being used on Halton’s iconic bridge project.

Webster and Trinity have been a great part of the borough’s landscape and while it is sad to see them go, we can really now see the progression of the river construction and I look forward to the bridge opening in autumn.”

Visit the Mersey Gateway YouTube channel to see how the MSS operates to build the deck of the approach viaducts:

The new bridge is scheduled to open in the autumn of 2017.

Further details

The Mersey Gateway completed. Image courtesy of Merseylink

The Mersey Gateway

It is a new six-lane cable-stayed tolled bridge across the Mersey Estuary between Runcorn and Widnes. The central feature of the significant highway improvements between the M56 and Speke Road. 


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