Bridge-building machine Trinity finishes work in Widnes for Mersey Gateway

Trinity, Mersey Gateway’s giant bridge-building machine, has finished work in Widnes signalling next big milestone.

Work has been completed in Widnes by onne of the Mersey Gateway’s two giant bridge-building machines, marking another milestone for the project team.

The moveable scaffolding system (MSS), cast the final central span of the elevated north approach viaduct this week.

The machine has so far construction 11 road deck spans, creating one seamless structure that sits on tip of the supporting bridge piers that stretch across the saltmarsh. In total, approximately 14,200m3 of concrete has been used during construction of the central road deck section, measuring a total length of around 715 metres.

Gareth Stuart, Merseylink’s Project Director, said: “This is another great achievement for the project. We now have the central section of the road deck complete and expect the entire north approach viaduct to be finished within the next couple of months. This key piece of road infrastructure is one of two elevated approach viaducts that will connect the new bridge to the main road networks in Widnes and Runcorn improving links between the two towns and the wider region.”

The approach viaduct decks are constructed in three phases. Once the central spans have been constructed by the MSS, a deck slab is built on top of the span, and finally the outer deck or ‘wings’ are built by a wing traveller machine to provide the full six-lane width of the approach road.

Most MSS machines are only capable of building bridge spans of up to 60 metres, but Trinity was specially designed to be able to cast spans of up to 70 metres, making it the longest MSS in Europe.

With its work now done, Trinity will be dismantled, reused and recycled.

It will take construction teams around two months to take the machine apart as they contend with approximately 1,200 components, 3,000 actual parts, and over 60,000 bolts.

Declan Cannar, Merseylink’s General Foreman in charge of the MSS, said: “It should take us around eight weeks to dismantle Trinity. The main part of the machine, the steel structure, will be transported to Slovakia, where it’s going to be used to build a bridge in Bratislava, while the casting cell will be recycled as this particular section was a bespoke piece specifically designed for the Mersey Gateway bridge.”

Many locals have been following the machines progress via the Mersey Gateway webcam.

Councillor Rob Polhill, Leader of Halton Borough Council, said: “Watching Trinity in action has been remarkable. To see the road deck of the north approach viaduct progress over the past 12 months has been a privilege. Not many people across the world are able to watch such a magnificent piece of engineering machinery in action.

“The images and footage of Trinity will certainly be enjoyed for generations to come. I look forward to now watching our second MSS, Webster, make its way toward the south side of the bridge.”

The Mersey Gateway bridge is on schedule to open in autumn 2017.

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