Humber Bridge Bearing Replacement
The project is to replace four solid steel “A-frames”, which connect the main span bridge deck to the towers at either end of the bridge. The A-frames each weigh five tonnes and are below the 1,410-metre main span of the bridge. They have to be replaced because the A-frame bearings, which allow them to move as the bridge contracts and expands with the weather, have become worn over time. The wear and tear has been exacerbated because of the dynamic forces on the giant structure over the 32 years since it was built, including the prevailing westerly wind blowing across the Humber estuary.
Expert analysis indicated that complete replacement of the system was necessary and would provide a much improved, lower maintenance solution for the Humber Bridge Board.The contract follows Hull-based Spencer Group winning tenders to project manage an inspection of the suspension cables in 2009 and to use a world-leading gantry system to enable vital main cable dehumidification work to prevent corrosion of the cables in 2010.The latest project is complex and will be carried out in cramped areas below the carriageway.
.Spencer are applying a design solution developed by leading international engineering consultants, ARUP.It will involve Spencer fitting two so-called “wind shoes”, which are designed to absorb wind loading on the bridge deck and reduce the associated loads on the new bearing system.Spencer-designed temporary, hydraulically-operated, load-bearing “arms” will be installed to enable the A-frames to be dismantled and removed, before the permanent solution is put in place, to precision engineering standards, thereby minimising the load pressure on a critical part of the structure. Concrete strengthening work will also be carried out.
The contract reinforces Spencer Group’s reputation for complex, high-level bridge works. The Humber Bridge Board has announced the works will require the closure of the nearside lane in both directions to reduce the load on the structure whilst the work is carried out and to enable safe access to the working areas.