Hammersmith Bridge Stabilisation To Cost Less Than Expected | |
Council to proceed with project that will be finished within a year
Hammersmith & Fulham Council (H&F) have announced that they have approved a plan for the stabilisation of Hammersmith Bridge that will allow it to stay open for pedestrians and cyclists. The recent reopening of the bridge was based on the use of temperature control systems but safety experts have ruled that this could only be temporary and a more permanent solution was needed. Originally a proposal had been made by engineers Pell Frischmann which was budgeted to cost £30 million but now the decision has been made to proceed with an alternative scheme by Mott MacDonald which would cost only £6 million and be completed in under a year. Following this a more extensive strengthening and restoration project would begin which would eventually allow motor vehicles to cross the bride again. H&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 scheme presented by Pell Frischmann. As well as saving £24m and reducing the works programme to 46 weeks, the new plan – which the council says has been favourably reviewed by Heritage England – is expected to reduce the need for temporary closures. Engineers believe it will also avoid the need to divert the gas mains on the bridge for the stabilisation work. Dr Denton’s report states, “The design concept for the Pell Frischmann proposal is to construct an external frame that provides an independent load path, eliminating reliance on the pedestals until they are strengthened and new bearings are installed. Given the uncertainties about the pedestals at the time the concept was first developed, it is entirely understandable why such an approach was initially taken.” The Mott MacDonald solution 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. Dr Denton said the Mott MacDonald proposal benefits significantly from the insight gained from the refined pedestal analysis engineers have done over the last year. He said, “As a result, jacking to enable bearing replacement is undertaken using the pedestal itself, with the robustness of the pedestal having been enhanced prior to jacking.” The proposal was presented to engineers and officials from the Department for Transport (DfT) and Transport for London (TfL) at a meeting with Dr Steve Denton and H&F engineers held on 9 August. H&F Leader Cllr Stephen Cowan has agreed and signed an Urgency Report. He 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.” The council will fund the £6m package in anticipation that the DfT and TfL will subsequently reimburse the council with their one-third shares as outlined in the Government’s TfL funding announcement of 1 June 2021. H&F expects to keep the bridge open to pedestrians and cyclists for the vast majority of the duration of the works, but there may be short programmed periods of closure to allow some works to take place safely. Advance warning of any closures to minimise disruption will be given. Cllr Cowan said, “Having reopened the bridge to pedestrians, cyclists and river traffic earlier this month, we are keen to press on with the next phase of work. I am grateful for the advice from Professor Denton and look forward to reaching agreement with the Government and TfL on the funding of the stabilisation and full repair works.” H&F is developing a Memorandum of Understanding (MoU) 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.
August 16, 2021 |