A SENSITIVITY ANALYSIS OF THE KEY ENVIRONMENTAL NOISE MODELLING DRIVERS BEHIND MONETISING OF HIGHWAYS SCHEMES

摘要

Accurate environmental noise modelling for road schemes may be required to create monetised noise impact values. The value of noise impacts is driven by how a road scheme impacts receptors that are sensitive to road traffic noise. As an example, the value of noise impacts is a key deliverable for a Highways England road scheme at Project Control Framework (PCF) stages 1 and 2 but the assessment must be proportionate as design is at an early stage. There is an inherent tradeoff between model fidelity and the simplifying assumptions used to create it - more simplifications produce less accuracy, but model production consumes less resource. Moreover, while a key deliverable is the value of noise impacts, the need often arises for a breakdown of the distribution of noise impacts to groups of receptors. This can lead to an inefficient working style of analysing the results by request. These issues may be solved by either improving the speed of modelling, and thus providing more time for analysis, or by making analysis more efficient. This paper explores the factors that influence the value of noise impacts such as the distribution of receptors around a road scheme and the changes in alignment of typical road schemes. It is based on previously assessed road schemes and examines their population distribution in relation to roads in rural and urban communities. The primary target of this paper is not to replace environmental noise modelling, but to understand the limitations of applying a simplified method of calculating noise levels within the context of a valuation of noise impacts.