Assessing Methodologies For Calculating Road Traffic Noise Levels In Ireland-converting Crtn Indicators To The Eu Indicators (l_(den), L_(night))

摘要

To comply with the EU Noise Directive 2002/49/EC, Member States are required to produce strategic noise maps for designated areas, including mapping road traffic noise from major roads. These maps must be presented using the EU indicators L_(den) and L_(night). However, the most common noise indicator used in Ireland at present is the L_(A10,18h) indicator arising from the use of the Calculation of Road Traffic Noise (CRTN) prediction method. Therefore, a relationship needs to be established between L_(A10,18h) and L_(den) and L_(night), separately. In addition to noise mapping these indicators are used for noise abatement purposes, so the proposed relationship must be accurate and robust. In 2002, the UK's Transport Research Laboratory (TRL) published a paper describing mathematical procedures that could be used to convert values of L_(A10) to L_(den) and L_(night). These procedures were then adopted for use in Ireland. This paper examines the suitability of the TRL conversion methods 1 and 3 for use under Irish road conditions. Method 2 was not considered in this study, as it was a methodology not applicable in an Irish scenario. Studies concluded that where hourly traffic data are available, the conversion methodology outlined in TRL Method 1 is robust and reproducible. However, in the absence of hourly traffic data where daily traffic counts are used, the relevant conversion procedures produce variable results for both L_(den) and L_(night) when applied to Irish road conditions. To reduce the variability, new conversion procedures were developed, specifically for Irish road conditions.