1987 Nov. Work started on Building Blaydon Bridge. November 1987, working exactly to the contract drawings. The inevitable unexpected happened during the excavation, in a cofferdam, for the southern main pier, whose foundation was planned to sit on sound sandstone rock below the river bed. In two corners, totalling about a quarter of the load bearing area, the rock was not good enough. It was broken up and mixed with sand and clay, probably the result of ancient glacial activity; It was decided that the pier foundation would be strengthened by piling. The preferred solution was a large number of mini-piles using small drilling rigs which could operate from the bottom of the hole, inside the cofferdam. The consequences of the unforeseen change of design were considerable. There could be a delay of about six months, prejudicing the 1990 completion date, and costs would increase substantially. However, Edmund Nuttall Ltd were authorised to increase resources to recover lost time although this would incur further expense. The work proceeded satisfactorily, and the construction of the superstructure by cantilevering followed.
Posted on: Fri, 12 Sep 2014 10:02:20 +0000
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