27 May, 2022 By Greg Pitcher
Contractors are being invited to register their interest in carrying out the permanent strengthening of Hammersmith Bridge.
The London Borough of Hammersmith & Fulham has alerted contractors to the £130M contract ahead of formal procurement later this year.
The council published a prior information notice regarding the deal to cover Stage 2 of its programme to restore the 135-year-old structure.
Hammersmith Bridge, which carries the A306 over the River Thames in west London, has been closed to motor vehicles since August 2020, when cracks in the structure were found to have expanded during a heatwave.
Although it reopened to pedestrians and cyclists in July 2021, and a £9M stabilisation project led by contractor FM Conway began earlier this year to protect this temporary arrangement, far more extensive works are required to allow the crossing to revert to full use.
The council said it was investigating its “engineering options” and that the “indicative capital cost” of Stage 2 works was between £80M and £130M.
It added that it was considering a range of options for the delivery of works, including a design, build, finance and maintain model, and a more limited design-and-build contract.
“London Borough of Hammersmith & Fulham wishes to conduct an early market consultation exercise to seek feedback from the market on the proposed commercial structures and risk allocation, and to gauge the level of appetite for the proposed approaches,” said the notice.
Further market engagement may be carried out before a full contract notice is issued later this year.
A technical study by architects Foster + Partners and bridge engineers Cowi last year found that a temporary double-decker crossing, using the existing bridge foundations, would cost about £100m – getting cars across the river again more quickly and cheaply than alternative proposals.
In March, Foster + Partners and Cowi were awarded funding by Hammersmith & Fulham Council to carry out further development of the double-decker solution tabled to aid the restoration of Hammersmith Bridge. A full feasibility study is now being carried out as part of a £3.5M investment by the council which will also cover ground investigations around the bridge’s foundations, crowd-loading studies and traffic modelling.
NCE understands that a decision on whether or not to advance the double decker solution is yet to be taken.
The double-decker solution involves building a new raised truss structure above the existing road deck. The structure will consist of two sections launched from abutments at either end of the bridge.
They will then be pushed through Hammersmith Bridge’s existing tower opening towards the midspan where the two sections will meet in the middle.
A vehicle ramp is then installed at either end to allow access to the upper deck of the temporary structure.
At first pedestrians and cyclists would use the upper level and the lower level would be used as a construction site; giving workers access to the Victorian structure’s deck and hangers.
This would allow contractors to remove Hammersmith Bridge’s existing deck in sections and drop them on to barges in the Thames to be taken offsite for refurbishment, lessening the load on the structure which in turn allows for motorised traffic to use the temporary crossing.
Once Hammersmith Bridge’s deck has been successfully removed the lower level of the temporary crossing will then be used by pedestrians and cyclists, while the upper level would allow motorists to cross the Thames.
Click here for more on the double-decker solution.
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