According to some bridge engineers, there are two basic problems with the designs for Sunderland’s (UK) £118million New Wear Bridge.
First, it is a shocking piece of bridge engineering.
Second, it is an absolute waste of money.
Produced by architect Spence Architect and structures consultant Technika, the designs involve a steel/concrete composite bridge featuring two cable stay towers, one 180 metres tall and the other 140 metres tall, on either side of the deck. A report in the UK’s New Civil Engineer magazine says the towers taper and curve toward each other longitudinally, overlapping when viewed in elevation. Despite the overlap above deck level, the report says, there is no physical connection between them.
Bad Engineering
Independent bridge expert Simon Bourne does not mince words when describing the engineering features of the design produced.
“The bridge is about as structurally inefficient as you can imagine,” Bourne says.
Basic problems, he says, stem from two core issues associated with the towers: their unusual shape and the lack of connection between them.
First, they must be able to resist extremely high bending forces, meaning the structures – and hence the cost – are much larger than what would be needed for a conventional cable-stayed structure.
Then, there is the difficulty of actually building the thing. The unusual layout, Bourne says, will make it more difficult for engineers to balance the forces going through the towers as contractors attach the cables to the deck, making the structure much harder to build than would otherwise be the case.
Because of this, Bourne says, contractors will have to follow more than 400 individual instructions to keep the structure stable during construction.
Is this really what austerity is about?
As if that weren’t bad enough, the bridge as designed would be four to five times more expensive to build than a standard box-girder road bridge, the New Civil Engineer report says.
It is this use of funds, at a time of supposed austerity, that riles Bourne the most, to the point where he has written to transport secretary Justice Greening urging him to withdraw the £82.6 million the Department of Transport has committed to the project.
“A bridge of this type is a gross misuse of public money in a time of austerity,” he says.
Apart from the Department of Transport’s contribution, the Sunderland City Council is contributing £31.9 million whilst £3.5 million will come from former regional development agency One North East.
Bourne’s concerns are shared by other bridge experts, partly because of the design’s complexity but also because the already completed design of the bridge leaves little room for contractor innovation.
Moreover, the apparent extravagance of the chosen design is likely to raise eyebrows of many engineers across the country: at a time when budgets for infrastructure and other programs are under strain, is such an expensive design really appropriate?
Many, no doubt, would say it is not.
