Bridge experts this week slammed designs for Sunderland’s £118M New Wear Bridge as a “staggeringly poor example of bridge engineering” and a “scandalous waste of public funds”.
Bridge engineers told NCE that the steel/concrete composite bridge between Castletown and Pallion would be four to five times more expensive to build than a standard box-girder road bridge and called for a halt to funding.
Designs produced by architect Spence Architect and structures consultant Technika include two cable stay towers - one 180m tall and the other 140m tall - on either site of the deck. The towers taper and curve towards each other longitudinally, overlapping, when viewed in elevation. Despite the overlap above deck level, there is no physical connection between them.
“Gross misuse of money”
“A bridge of this type is a gross misuse of public money in a time of austerity,” said independent bridge expert Simon Bourne. Bourne has 30 years’ experience in designing major bridges and has also been vocal in his criticism of the Mersey Gateway..
He has written to transport secretary Justine Greening outlining his concerns and urging her to withdraw government funding
The Department for Transport committed £82.6M to the scheme’s £118M total cost last December. Client Sunderland City Council is contributing £31.9M, with the remaining £3.5M coming from former regional development agency One North East.
His concerns were supported by other bridge experts. They said it was partly because the bridge will be very complicated to build, adding that as the bridge is already fully designed there is no room for contractor innovation.
“It’s a really complicated bridge, and completely unnecessary for a span of this length,” said an expert close to the project. “I just can’t believe it’s got this far [towards construction],” added another prominent bridge designer.
The unusual shape of the towers - and the fact that there is no connection between them - means that they must be able to resist extremely high bending forces. As a result they are much larger structures than would be needed for a conventional cable stayed structure, said Bourne.
“The bridge is about as structurally inefficient as you can imagine,” he said.
The unusual layout also makes the structure hard to build as it is much more difficult for engineers to balance the forces going through the towers as contractors attach the cables to the deck.
As a result, contractors bidding for the project have a heavily prescribed construction schedule, eliminating scope for design innovation said the engineers who spoke to NCE.
Bourne said contractors will have to follow more than 400 individual instructions to keep the structure stable as it is built.
“In normal bridge schemes, contractors would be given a dozen indicative construction stages and it would be up to the contractor to decide on the best system for them,” said Bourne.
The council denied the project has been over engineered. New Wear Crossing project director David Abdy said the project had been “rigorously designed, costed, admired and backed within the industry and profession”.
The council is promoting the iconic bridge over a cheaper alternative to stimulate regeneration while relieving traffic congestion in eastern Sunderland.
Spence and Technika’s design won a Royal Institution of British Architects competition in 2005. But the scheme was mothballed until 2008 when the council announced that it was considering a simple alternative similar to a box girder option, that would be £21M cheaper. This option was rejected following a public consultation and planning permission was secured in April 2010 based on the current, iconic design.
But Bourne also criticised Sunderland City Council’s attempt to justify the design on the basis that the bridge would attract new investment.
Bourne said Sunderland’s comparisons with the nearby Millennium Bridge in Newcastle - on which the justification is based - are unsuitable.
“The Millennium Bridge is a footbridge in the centre of town,” The Wear Bridge is a serious piece of infrastructure in the middle of an industrial estate,” said Bourne.
Five contractors are bidding to build the two span, 336m long cable-stayed structure. Balfour Beatty, Vinci, Ferrovial, Skanska and Graham Construction are understood to have been shortlisted. The council hopes to select its preferred bidder later this year with construction starting in 2013. Target completion date is 2015.