What do the contour levels mean?
The noise contours shown on the maps show annualised average outdoor noise levels resulting from heavy railway vehicle passages on the Iarnród Éireann network. The indoor noise levels at any particular building or residence are a function of construction of the building and whether there are any other influencing factors (i.e. open windows, structural changes, etc).It should be noted that people’s expectations for relative quiet and/or the effect of noise is subjective. Impacts of environmental noise is also relative to normal background noise levels. This can be significantly different between agglomeration (urban) areas and rural areas. It can also be different within agglomeration areas where streets are quieter by virtue of different exposure to transport or industrial noise. People’s appraisal and annoyance to noise is also dependent on the type and frequency of noise and their how habitualised they are to a particular noise source.