The A12 widening has brought carriageway edges to within 4.5m of piers supporting two overbridges and one footbridge. This means supports have had to be strengthened to resist impact loadings and the Highways Agency has taken the opportunity to refurbish all five structures within the 4.5km of Fitzpatrick's contract.
Weald Road overbridge needed the most work. The steel and concrete composite deck has been raised 670mm due to the combined effect of overlaying and widening the road and the requirement for new structures to provide 5.3m of headroom.
Abutments and parapets have been entirely replaced, as have the bridge's two piers, including bearings. Pier construction demanded special attention to programming as new bases had to be half built beneath the widened carriageway before temporary support could be erected, the existing piers demolished and the new supports completed.
'Weald Road was a big challenge, ' says Fitzpatrick project manager Dick Watts.
'There was a lot of work to complete inside limited time and access within the road maintenance programme.
Logistics were made more difficult by restricted land use.
Most plant and materials had to be stored and brought from a separate site at the next M25 junction. We had up to 45 different subcontractors working at one time so careful coordination of resources was essential.'