TAN 11 is the current Welsh government guidance on general noise and planning policy. It was produced by the then Department of the Environment (Now DEFRA) in October 1997 and replaced Welsh Office circular 16/73. The document talks about general principles in relation to noise and planning, and provides general guidance on both noise sensitive and noise generative developments, including draft planning conditions dealing with noise. The main detailed guidance provided in TAN 11 is the Noise Exposure Categories for new residential developments.
TAN 11 uses four Noise Exposure Categories (A-D) for assessing the suitability of sites for new residential development. Category A being areas where noise need not be considered as a determining factor in granting permission, and Category D being where planning permission should normally be refused. A table of noise levels is provided for day and night time to assess which category the site falls in to. Different noise criteria are provided for road, rail, aircraft and mixed source noise, with the criteria having been derived from various social surveys for different noise sources.
Some detailed guidance is provided on the assessment of noise from a variety of sources, but this guidance generally refers to other documents for methods of assessment and criteria.TAN 11 makes reference to BS 8233, CRTN, BS 4142, BS 5228.