Areas exposed to noise on the Charente-Maritime (areas of type A — index of type LN) Prefectural decree No 18-1536 of 24 July 2018

Type A noise zones — LN type index. Layer carried out by GIS workshop (April 2018) by compiling noise zones of type A related to road infrastructure (EREMA report on "Strategic noise maps of the department of Charente-Maritime (017) Large non-granted infrastructure; Deadline 3: 2017-2022") and motorway ("Non-technical summary of the mapping of the sound environment of the ASF network on the Charente Maritime department (17) in 2016") Noise zones are geometrical elements of the strategic noise map. These maps also known as “type a maps” represent for the reference year in the form of isophone curves, the areas exposed to more than 55 dB(A) according to the Lden indicator (case of this geographical layer) and to more than 50 dB(A) according to the Ln indicator, with a step of 5 in 5 dB(A). The noise level on a noise map is represented by regulatory indicators: the “Ln” (Level night) and the “Lden” (Level day-evening-night) are harmonised indicators at European level. The Ln is the average noise level for the night period (22h-6h). The Lden is the 24-hour weighted average noise level to take into account the discomfort experienced, vis-à-vis the same noise level, greater in the evening and at night compared to the day.