Highways Agency Standard BD 49 sets out the design requirements for bridges with respect to aerodynamic effects including the provisions for wind tunnel testing. This standard has recently been revised in response to developments in the understanding of the behaviour of bridges in wind and in particular in light of recent wind tunnel tests commissioned by the Highways Agency. Revisions have also been found to be necessary as a result of experience in using the standard since it was first published in 1993. This included clarification of certain clauses, which had been open to misinterpretation. This report presents the background to the revisions with a view to clarifying the scope of the revised document and the bounds within which the simplified rules are applicable. It also provides further references which can be consulted to assist in cases where the simplified rules are not applicable. (Author/publisher)
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