Researchers at the Bradford Centre for Sustainable Environments have developed a methodology by which the perceived tranquillity rating (TR) of an amenity area such as park, green or urban square can be measured, on a 0–10 scale. The method involves the assessment of average daytime noise levels Lday (usually traffic noise) and the measurement of the percentage of natural and contextual features NCF contained within the visual scene. The latter includes the percentage area in the visual scene occupied by natural features in the landscape such as vegetation, water and geological features, e.g. exposed rock outcrops, and contextual features. These contextual elements include listed buildings, religious and historic buildings, landmarks, monuments and elements of the landscape, such as traditional farm buildings, that directly contribute to the visual context of the natural environment. Lastly, the equation includes moderating factors (MF) that can influence the perception of tranquillity in either a positive, or a negative way: