FAQs relating to Interpretation of Strategic Noise Maps
Note: It must be noted that these Strategic Noise Maps have been produced only for the purposes of the Environmental Noise Regulations 2018 (as amended). Iarnród Éireann will not be held responsible for any outcomes that may arise from the use of these results by any party for any reason other than for the purpose of fulfilling the requirements of the Environmental Noise Regulations.
Ceisteanna Coitianta
The noise levels shown on Strategic Noise Maps are annualised averages for an average day in the year, and therefore do not show the specific noise from individual train passes.
The maps are only intended to be used for strategic assessment of noise levels in any given area.
Strategic Noise Maps should not be used to determine, represent or imply precise noise levels at individual locations (e.g. individual houses, windows).
The maps have been produced for use at a strategic level and give an acceptable level of accuracy for the purposes they were prepared (i.e. for focusing attention during the preparation and production on Noise Action Plans, by Local Authorities).
Strategic Noise Maps will not properly represent the situation at a local level and the results of the noise mapping should not be used alone for any land use planning or location-specific assessments.
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.A Strategic Noise Map shows banded annualised average contour noise levels resulting from noise generated by rail operations. Just as a weather map might have isobars joining points of equal air pressure, a noise map can have contours joining points having the same noise level.
Environmental noise is unwanted or harmful outdoor sound created by human activity, such as noise emitted from different means of transport or industrial activity. The issue of noise is subjective to the individual receiver, i.e. what is noisy for one person may not bother someone else.
Noise is measured in decibels on a logarithmic scale, such that a doubling of sound energy equates to a 3 decibel increase.LDEN is the noise level of day, evening and night (i.e. 24 hour noise level). Daytime extends from 07:00 to 19:00 (LAeq,12h), evening extends from 19.00 to 23.00 (LAeq,4h) and night-time extends from 23:00 to 07:00 (LAeq,8h).
LNight is the noise level the noise level of night only (i.e. 23:00 to 07:00 (LAeq,8h)).
In general terms and for conceptualisation, LDEN noise level is an indicator of noise annoyance and LNight noise level is an indicator of possible sleep disturbance.The maps represent an annualised average snapshot of the environmental noise from Heavy Rail operations for Q4 2021.