e-mosty September 2017: Mersey Gateway Bridge. Arenales Bridge. Mersey Gateway Bridge. Arenales Bridge. BLWT. - Page 15

3.4.6 Wing traveller machines Two wing traveller machines were used on the project – one for each of the approach viaducts. One wing traveller machine was used to build the outer road lanes on either side of the North approach viaduct in Widnes. It followed the project’s movable scaffold system (MSS), which constructed the central part of the carriageway. The second was used for the South viaduct. The wing traveller - sometimes called the Construct ion Cantilever Traveller - weighed 280 tonnes and was around 48m wide and 20m tall. It worked in a similar way to the MSS and the form traveller machines, acting as a movable concrete mould to complete the full deck width, which, at just over 43.5m at its widest point, carries six lanes of traffic. Completion of the bridge and viaduct decks involved water-proofing the deck, installing fascias along its sides, and laying the road surface. 3.4.7 Ancillary items - Windshields To confirm aerodynamic stability and wind speeds on the bridge wind tunnel testing was used. Windshields are provided to reduce overturning moments on high sided vehicles. On the West side of the deck the windshields are significantly higher than those on the East side reflecting the prevailing wind direction. Testing was undertaken on a representative high sided vehicle, see Figure 21. The machine was fixed onto two railway tracks that sit on top of the deck section that had already been cast by the main section MSS. To maintain balance concrete was poured into both sides of the machine at the same time, enabling workers to cast 12 metre sections of the outer deck on each side of the viaduct. Once the concrete had set, hydraulic jacks pushed the machine forward to the next position and the cycle was repeated. Figure 21: Windshield testing on high sided vehicle References and sources: KNIGHT, Martin – HALACZEK, Bartlomiej: Securing visual quality and architectural intent while aiming for an affordable tender design – the procurement of the Mersey Gateway Crossing. Knight Architects, High Wycombe, United Kingdom. 39th IABSE Symposium – Engineering the Future. September 21-23 2017, Vancouver, Canada SANDERS, Paul – BRENNAN, G. – WOOD, H. – BANKS, J. – ROMO MARTIN J.: Mersey Gateway Bridge (UK) – Design for Construction. 19th IABSE Congress. Stockholm 2016 Figure 20: The wing traveller machine in its starting position at the North approach viaduct in Widnes http://www.merseygateway.co.uk/ Sixty-two concrete pours were needed to create the outer deck of the North approach viaduct, while 47 pours took place for the outer deck of the South approach viaduct. Each pour consisted of around 80m 3 of concrete (40m 3 each side). https://www.peri.com/en/projects/civil- engineering/mersey-gateway-bridge-runcorn-to- widnes-great-britain.html 3/2017