Structure has been closed since August
Foster & Partners has unveiled plans to build a temporary double-decker crossing within the existing structure of the bridge.
The proposal (see attached pdf below), which has been presented to Hammersmith & Fulham council, says pedestrians, cyclists and, potentially, cars and vans would be able to use the bridge during its repair and restoration.
A new raised truss structure would be built above the existing road deck, featuring a lower level for pedestrians and cyclists and an upper level for cars and buses.
The raised deck would enable existing approach routes for traffic to be used, causing minimum disruption for residents on both banks of the river.
The structure will also provide support for the bridge as well as a safe platform for restoration work to be carried out.
The new truss structure would be assembled in two halves and launched from each side over the existing road surface. It will be supported on each bank and at the two existing piers.
As a result, there will be no added load on the existing bridge deck. Elements of the grade II* listed bridge that need repair, including pedestals, anchors and chains, would be lifted away and transported by barges to an off-site facility for safe repair and restoration.
Contractors would be able to use the new lower pedestrian deck to access the works. When completed, the temporary raised deck would be removed.
Fosters said that by repairing the bridge off site, the restoration could be done at greater speed and at significantly reduced cost.
The proposal has been advanced working in partnership with bridge engineers Cowi, who have experience in the refurbishment of existing structures.
It comes as a taskforce set up to get Hammersmith bridge up and running again said it expected to appoint contractors shortly to start repairing pedestals at the structure closed since the summer.
In September, the government tasked the group, chaired by transport minister Baroness Vere, with making sure the 133-year-old cast-iron bridge is reopened.
It includes project director Dana Skelley, a former head of London’s road network at Transport for London (TfL) and now an independent consultant, along with representatives from Hammersmith and Fulham and Richmond councils as well as the GLA, TfL and the Port of London Authority.
The taskforce has had seven meetings and the latest last month said TfL would begin work to repair its two western pedestals as part of wider bridge stabilisation work.
The bridge was closed to motorists in April last year after cracks were detected but remained open to pedestrians and cyclists.
But it was fully closed and fenced off in the middle of August after the cracks were found to have widened during a heatwave.
TfL and local authority Hammersmith and Fulham council are working up a business plan to carry out repair work ahead of it reopening.
In the meantime, a temporary ferry service is planned to start criss-crossing the Thames from next spring.
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