I was most interested, if somewhat surprised, to read that the Greta Bridge at Keswick has been nominated by the Concrete Society as Britain's best civil engineering structure of the century (NCE 4 November).
My interest stems from the fact that I was the structures agent for the contractor, Tarmac Construction. My surprise is at the Concrete Society's apparent change of heart. In 1977, the Society adjudged it worthy of no more than a Highly Commended award.The article in NCE refers to the varying depth of the structure's deck, but this is only one feature of its complicated shape. In plan, the bridge follows a reverse curve which requires a constantly changing carriageway crossfall from one abutment to the other. In turn, this varying crossfall geometry is repeated in the crosssectional alignment of the deck itself, resulting in webs which, although apparently vertical, are actually at right angles to the deck soffit and upper slab.
Even before reaching this stage of construction, we had experienced enormous problems in founding one of the abutments and in devising a support system for the adjacent end span of the deck (NCE 8 April 1976).
No doubt the design of this bridge resulted in an aesthetic masterpiece but, alas, it was hopelessly inadequate from the viewpoint of buildability. Nevertheless, I think I can speak for all of us involved in its construction when I say that we remain immensely proud of what we achieved.Peter Donaldson (M), Stone Croft, Main Street, Great Longstone, Bakewell, Derbyshire, DE45 1TA