The Mersey Gateway project has passed a significant milestone, with construction teams having built over half of the new main bridge deck over the River Mersey. Work to install stay cables on the main bridge also passed a key point on the south pylon.
Construction teams installed a 150m long cable to be connected. It marks the exact halfway point for stay cable installations on the pylon.
When complete 146 stay cables will support Halton’s new 1,000-metre long reinforced concrete bridge, with a combined load-bearing weight of more than 53,000 tonnes.
Gareth Stuart, Project Director of the Merseylink construction joint venture, said:
“These are two massive achievements for the project. The deck and the cables are integral to the design of the Mersey Gateway bridge, and will make it instantly recognisable as one of the most impressive looking crossings in the UK.
“We’re now more than 50% through this highly visual phase of the Mersey Gateway construction, where people will be able to see the stay cables connected to the bridge deck as it emerges across the river week by week.”
Each stay cable consists of up to 91 individual steel strands that sit inside a stay pipe – this is the outer casing that provides protection from weather-related corrosion. More than 810 miles of the strands will be used on the project, around the same distance from John O’Groats to Land’s End.
Every single strand needs to be installed individually as Merseylink’s Design Manager, George Moir, explains:
“It’s gone well so far, and we’re installing around 6 stays per week from the three pylons. The first two strands are threaded through the stay pipe then the tower crane lifts the pipe up to the anchor point in the upper pylon where the top ends of the strands are fixed into place.
The bottom ends of the strands are then attached to the anchor point in the bridge deck and stressed using a hydraulic system. This enables us to get the correct level of tension needed to support that segment of bridge deck. We then use a winch system through the stay pipe to winch the remaining strands up one by one. Once all of the strands have been installed they sit in parallel inside the stay pipe to form the stay cable.”
The stay cables vary in length; with the shortest measuring approximately 41 metres and the longest measuring 226 metres.
Cllr Rob Polhill, Leader of Halton Borough Council, said:
“Reaching the halfway point on the bridge deck, and installing half of the south pylon’s stay cables are both huge milestones for the project. It’s been fascinating to watch the works in the estuary progress, and we’re now set to see truly incredible scenes as our new bridge enters its final phases of construction.
“Every day the landscape of Halton is changing and I would encourage everyone to catch a glimpse of the work in progress.”
Stay cable strands and anchor samples are on display at the Mersey Gateway visitor centre located at the Catalyst Science Discovery Centre in Widnes.
Fascinating facts about the Mersey Gateway stay cables.