e-mosty September 2017: Mersey Gateway Bridge. Arenales Bridge. Mersey Gateway Bridge. Arenales Bridge. BLWT. - Page 14

3.4.4 MSS TRINITY Trinity, the 1,700-tonne, 157-metre long, movable scaffold system (MSS), built the central part of the carriageway. The machine – essentially a giant concrete mould – constructed 11 road deck spans, creating one seamless structure. Approximately 14,200m 3 of concrete was used during construction of the central road deck section, measuring a total length of around 715m. The MSS was specially made for the Mersey Gateway Bridge project. While most machines of this kind typically only build bridge spans of up to 60m, Trinity was specifically designed to be able to cast spans of up to 70 metres. Figure 17: Trinity starts work With its work done, and with sustainability as a key objective of the whole project, Trinity was dismantled, reused and recycled. It took construction teams around two months to take the machine apart as they comprised approximately 1,200 components, 3,000 actual parts, and over 60,000 bolts. The main element of the MSS Trinity, the steel structure, is to be transported to Slovakia, where it is planned for re-use in the construction of a bridge in Bratislava. The casting cell will be recycled separately as this particular section was a bespoke piece specifically designed for the Mersey Gateway Bridge. Figure 18: Final concrete pour 3.4.5 MSS WEBSTER MSS Webster was specially designed and built to construct the curved viaducts leading to the main bridge. The machine was named by Halton schoolchildren after local engineer John James Webster who built the Widnes Transporter Bridge. Webster is 157m long and 8m high. It is 22m across at its widest point and weighs 1,700 tonnes. In total it constructed eight spans of the South approach viaduct to create its central box section using 9,205m 3 of concrete. logistics. Additional pumps were used on top to give access to the concrete. After completion of the works MSS Webster will be dismantled and also transported to Bratislava to join its fellow MSS Trinity, which is being used to build a new bridge over the River Danube. Webster was assembled piece by piece approximately 12.5m above the ground around the first pier of the South approach viaduct, involving the project’s biggest ever crane lift - it was lifted into place with two giant cranes, one crane weighing 700 tonnes and the other 750 tonnes, working in tandem to hoist into place the 77m-long, 240 tonne main girder section. Operation of the MSS Webster above the Manchester Ship Canal required extra planning and a change in 3/2017 Figure 19: Webster above the Manchester ship canal during the concrete pour