11th August 2017
One of the most visible elements of the construction process for the New Wear Crossing in Sunderland will be disappearing shortly – opening up another view of the city’s new bridge.
The cofferdam, a giant steel box in the middle of the River Wear which has provided a dry area for the team to build the main bridge foundations from, is being slowly dismantled and is expected to disappear from view from the end of next week.
It will take an expert team of divers around three weeks to cut the 30m long cofferdam down to riverbed level – exposing the bottom of the pylon legs as they disappear into the water.
Working from a pontoon and using specialist underwater cutting equipment, 7 divers are removing the steel sheets in sections – up to 6m at a time – when tidal conditions allow.
With just over half of the cofferdam cut away, the sheet piles are gradually being removed during a carefully orchestrated operation, which is closely monitored by underwater cameras.
The dismantling of the cofferdam is the first of the major temporary river works to be removed – signaling a new phase for the New Wear Crossing project as it heads towards completion in the spring of next year.
The bottom of the cofferdam is part of the foundations for the bridge’s impressive A-frame centrepiece. It was made from 92 sheet steel piles that were installed in the river at the start of 2016. Once the box was constructed within the riverbed, the water could be pumped out – providing a dry, watertight space for the team to work from.
Stephen McCaffrey, Project Director, said, “the cofferdam has been an essential part of our engineering infrastructure on site for 18 months – enabling us to work within the river to build the foundations and to create the enormous tusks that the pylon now stands on".
“It’s played a major role in the project, but is now no longer needed, so the steel will be taken away and recycled.
"In a way, it’s a shame to see it go, but it’s a real sign of progress on site.”
Sunderland City Council Leader, Cllr Paul Watson, said: “It’s incredible to think how much effort goes in to creating temporary structures like the cofferdam on big projects like this.
"It’s been a real privilege to watch the team at work as they have progressed and it’ll be fascinating to see how the bridge looks when we get a clearer view of it across the river, without the cofferdam in place.”
The New Wear Crossing is the first bridge to be built over the River Wear in Sunderland for more than 40 years.