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Hammersmith & Fulham Council has thrown its weight behind a proposed temporary “double-decker” Thames crossing while Hammersmith Bridge is repaired.
The designs worked up by architect Foster & Partners and endorsed by consultant Cowi were presented to the Department for Transport’s (DfT) Hammersmith Bridge Taskforce yesterday, having won the support of Hammersmith & Fulham Council leader Stephen Cowan.
The solution involves building a new raised truss structure above the existing road deck featuring a lower level for pedestrians and cyclists and an upper level for cars and buses.
Under the proposal pedestrians, cyclists and motor vehicles can use the bridge, with river traffic passing underneath.
Backers of the “double-decker” proposal – which include property developer Delancey’s Sir John Ritblat – claim that it could be in place within a year of a contractor being appointed – much sooner than the previous plan.
They also claim that it can be built cheaper than consultant Pell Frischmann's proposal for a £27M temporary pedestrian bridge which would run parallel to the Victorian structure.
Initial estimates also suggest the temporary crossing would allow the strengthening and stabilisation works to the 133-year-old heritage bridge to be completed for less than than the current £141M estimate.
Under the plan, there no load would be added to the existing bridge deck which will be removed in stages for repair. Contractors would use the new lower pedestrian deck to access the works. When the repairs are complete, the temporary raised deck will be removed.
Elements of the Grade II listed bridge that need repair, including pedestals, anchors and chains, would be lifted away using the temporary bridge and transported by barges to an off-site facility for safe repair and restoration.
Cowan said: “I am extremely grateful to Sir John Ritblat for responding to our call for help so comprehensively. The Foster & Partners and the Cowi design team has developed an exciting and imaginative initiative which has the very strong possibility of providing a quicker and better value solution than any of the other proposals.
“Our engineers have held positive and constructive talks with Foster & Partners and Cowi. I am optimistic that we now have a viable option within our grasp that is a win for all. I commend it to the government in the hope that it will be the catalyst for real progress in funding all the necessary works to the bridge.”
Foster & Partners senior executive partner Luke Fox said: “We are excited to propose this simple solution to this important missing piece of London’s infrastructure that also gives the opportunity to bring back to life a beautiful and iconic bridge by Sir Joseph Bazalgette.”
Foster & Partners head of structural engineering added: “We believe that our concept resolves the two challenges for Hammersmith Bridge economically and efficiently: delivering a temporary crossing quickly, while providing a safe support to access and refurbish the existing bridge.
“We appreciate the engagement and contribution from the technical experts in charge of the bridge and look forward to further studies to develop the scheme”
Cowi executive director David MacKenzie added: “We consider that this approach is practical and viable. Our experience is that offsite refurbishment of bridge structures is safer and more controlled, and results in a higher quality final outcome when the structure is re-installed.”
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As always, the devil is in the detail. Its proposed that no load transfer occurs to the deck, but certainly transfer over the existing abutments/supports, which will be an interesting bearing detail to see. What about the containment? The indicative sketches here don’t reflect the significant parapet needed on the raised highway portion. Another thought would be why should this be only a temporary fix? the segregation of traffic and pedestrians here seems to be a great long term solution, although I suspect the new structure would have to look considerably smarter if it became permanent.
Surely the collapse of the Florida International University Bridge would put anyone off fiddling around with a structure while allowing traffic to use the same space – even more so since this bridge is recognised as being in danger of collapse.
This proposal is a welcome addition to the Hammersmith Bridge debate and it is interesting to see that it has generated support for a temporary bridge that can carry road vehicles. However the devil is in the detail and the height from the roadway to the springing of the arch in Section A-A is only 6m, see https://www.abasurveying.co.uk/portfolio-items/hammersmith-bridge/
With a single decker bus being 3m high that leaves very little height for the structure of the temporary bridge and its two decks. It would seem that the roadway may need to be single carriageway through the arches if buses and ambulances are to use it.
Very clever. But I. like Stepehen Wal – and how can river traffic pass beneath it, if it is considered unsafe atv present to bear even thesh, am not clear what will bear the load of this temporary span? Is it entirely self supporting or is it resting on some part (the pedestals?) of the exisiing bridge? How can the exising bridge support ANY load it is at present unnsafe to carry the weight of even cyciots and pedestrians? Are we to understand that the whole span can support itself simply on its two ends on either bank
As ever Consultants have gone mad !!! Contractors put in temporary bridges all the time. Any half decent Contractor’s temporary works department would contact Maybe Bridge( I have no contact with them but have used them in the past), a few tubular piles in the river and construct a temporary bridge over the river using their well known systems.