Hammersmith & Fulham Council has accepted plans to repair Hammersmith Bridge to a level which stabilises it for pedestrians and cyclists, which are £24m cheaper than the former scheme.
The Council announced their decision to save 80% of the cost of stabilising Hammersmith Bridge on Monday 16 August, by replacing a £30m scheme by engineering consultants Pell Frischmann scheme with a cheaper one by Mott MacDonald.
They’re hoping that Hammersmith Bridge could be stabilised for pedestrians and cyclists within a year.
The council’s specialist engineers Mott MacDonald devised the alternative stabilisation plan, which will cost £6m instead of Pell Frischmann’s £30m scheme and promises also to reduce the works programme to 46 weeks.
LBH&F commissioned Dr Steve Denton, Head of Civil, Bridge and Ground Engineering at consultants WSP, to compare the two options to stabilise the bridge’s cast iron pedestals. He concluded that the one proposed by Mott MacDonald would be technically superior, implemented more rapidly and more cost efficient than the £30m scheme presented by Pell Frischmann.
The Pell Frischmann proposals would have seen an external frame constructed which would remove the load on the pedestals until they were strengthened. But Denton said this approach, which would also require driving piles through parts of the bridge, had been developed before in-depth studies of the pedestals had been carried out.
The Mott MacDonald plan will see the bridge’s bearings replaced by jacking using the pedestals themselves, which will be strengthened beforehand. The plan involves the use of ‘elastomeric bearings’ which allow any pressure to be applied equally to all four corners whilst protecting the vulnerable 134 year-old cast iron structure.
Above: Hammersmith Bridge – Photograph by Matt Smith
Bridge to remain open for “vast majority” of works
The 19th-century crossing was closed to road traffic in April 2019 when a structural integrity review revealed seven decades of unchecked corrosion. The bridge was then closed to pedestrians, cyclists and river traffic on public safety grounds in August 2020 after it was found to be at risk of a catastrophic collapse.
The bridge was reopened to pedestrians, cyclists and river traffic on 17 July 2021 but safety say the use of the temperature control system, which enabled the reopening, can only be temporary.
The Council expects the bridge to remain open for pedestrians and cyclists for the “vast majority” of the works, which it said will be completed in under a year.
Image above: Leader of Richmond Council Gareth Roberts (left) and Leader of Hammersmith and Fulham Council Stephen Cowan (right) visiting Hammersmith Bridge in 2019
Council leader pushes through proposals
Council leader Stephen Cowan has given authorisation for the job to progress immediately, saying the local authority does not want to “lose a single day” in fixing the bridge.
Cllr Cowan said:
“We don’t want to lose a single day in delivering the full stabilisation of the bridge to ensure residents on both sides of the river no longer have to deal with closures or the threat of closures.
“Whilst putting the safety of the public first, we believe that the importance of maintaining pace and progress, the real savings achieved by the deployment of the preferred stabilisation works option and the current vulnerability of Hammersmith Bridge demands rapid action.”
Cllr Cowan said, in order to expedite the works at speed, the council will go-ahead and fund the £6m package in anticipation that the Department for Transport and Transport for London will subsequently reimburse the council with their one-third shares as outlined in the Government’s TfL funding announcement of 1 June 2021.
Image above: Foster & Partners Hammersmith Bridge proposal
Funding proposal and next steps
LB Hammersmith & Fulham is developing a ‘Memorandum of Understanding’ with the DfT and TfL incorporating financial proposals to share costs of the work between the three bodies.
The pedestrian stabilisation plan is the first phase of works on the bridge. The second phase will involve extensive strengthening and full restoration and will allow the bridge to reopen eventually to vehicles.
Dr Denton is now considering the two current options for the strengthening and restoration work – the existing TfL plan and the pioneering Fosters + Partners/COWI proposal for a temporary double decker truss.
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