The Part 2 AST should illustrate the number of people experiencing a significant increase/decrease in noise levels. For strategic and project level appraisal, the AST should summarise the relative annoyance responses and affected populations for the existing situation, a do-minimum scenario and the proposed scheme. At the strategic level, the change in the number of people annoyed over geographical zones may be an adequate proxy in the absence of more accurate information. Estimated populations affected by changes in noise of greater than 3dB(A) can also be indicated on the AST. The qualitative assessment should relate to the subjective response to noise levels, noting for example, the presence of sensitive receptors such as hospitals, or if the scheme is introducing noise into a previously quiet area where traffic was not the dominant noise source. At project level, the annoyance response summary should be based on modelled noise contour information. Worksheets N1 and N2 in Section 17.5 may be used to assist in the assessment of an option’s impact in terms of noise and vibration.
