New aerial pictures reveal Mersey Gateway taking shape as heavyweight moving scaffold system completes its job casting northern elevated viaduct

The bright orange movable scaffolding system nicknamed Trinity has cast the final central span of the elevated north approach viaduct.

This means the innovative concrete formwork machine has constructed 11 road deck spans, creating one seamless structure that sits on top of supporting bridge piers running across the saltmarsh.

The MSS was specially made for the Mersey Gateway bridge. While most machines of this kind can only build bridge spans of up to 60 metres, Trinity was specifically 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.

MSS Trinity’s final concrete pour underway

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

Gareth Stuart, Merseylink’s Project Director, said: “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.

Trinity measures an impressive 157m long and weighs around 1,700 tonnes.

Declan Cannar, Merseylink’s General Foreman in charge of the MSS, said: “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.”

110m tall north pylon

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