The Mersey Gateway Project to build a second river crossing, between Runcorn and Widnes, has achieved another milestone with the first deck span for the elevated north approach viaduct now completed.
The reinforced concrete deck span is the first of 11 spans that will be cast by the special movable machine for the deck, or roadway, of the elevated approach viaduct on the north side of the River Mersey. This span connects the beginning of the approach viaduct from the north abutment in Widnes to the first supporting pier.
The enormous structure measures around 60 metres long and 18 metres wide. It is angled at five degrees to allow vehicles to travel safely around the curve of the approach road.
Declan Cannar, Merseylink’s general foreman, who is in charge of the MSS operation, said: “This is a real achievement for the project and a milestone that we’ve been looking forward to with anticipation. Our construction teams have put a considerable amount of time and effort into constructing this initial span so it’s great to see it finished. We’re now busy preparing the movable scaffolding system so it’s ready to cast the next section.”
Construction teams worked around the clock to get the span ready. This involved pouring 1,146 cubic metres of concrete into the MSS non-stop over a period of 34 hours.
Cllr Rob Polhill, Chair of the Mersey Gateway Crossings Board and Leader of Halton Borough Council, said: “This is such an exciting moment for the project and it is fantastic that we can now see a completed span of the approach viaduct. You can track Trinity’s journey via the live view webcam on the Mersey Gateway website and it’s well worth a look. This remarkable example of engineering is truly special and I can’t wait to see its progress over the coming months.”
The approach viaduct deck is being constructed in three phases. The deck spans are constructed first by the MSS, then 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.
The MSS has moved to its second casting position ready for work to begin on the next span, which will be cast in March.
The deck of the approach viaducts is being constructed in three phases. The MSS is building the deck spans in phase one, which are a trapezoidal shape. Formwork is used in phase two to create the deck slab, and finally a ‘wing traveller’ machine builds the outer deck in phase three. The process for creating each deck span in phase one involves placing the external formwork, installing rebar reinforcement and then the internal formwork to create a casting cell.
Continuous topography and monitoring takes place to ensure correct levels prior to the concrete pour. The concrete is then poured. Once the concrete has ‘set’ a hydraulic system moves the MSS apart and forwards to its next casting position.
The Merseylink Consortium was appointed by Halton Council as the project company in 2014, on a 30-year contract to design, build, finance and operate the project. Its equity partners are Macquarie Capital Group, BBGI, and FCC Construcción. The construction joint venture is made up of Kier Infrastructure & Overseas, Samsung C&T Corporation and FCC Construcción S.A. Sanef S.A. will deliver and operate the tolling solution for the consortium.
The bridge is due to open in 2017.