Transparency data

Explaining the 2022 noise maps

Published 22 October 2024

Applies to England

1. Background

Environmental noise mainly consists of noise from transport sources such as road, rail and aviation. One of the ways Defra manages this noise is by implementing the regulations.

The regulations require that, every 5 years, Defra:

• adopts noise maps which show people’s exposure to environmental noise

• adopts action plans based on the results of noise mapping

• aims to preserve environmental noise quality where it is good

• provides information to the public on environmental noise and its effects

This information relates to the maps produced for the fourth round of this 5 yearly cycle (hereafter referred to as ‘round 4’).

Defra is responsible for creating noise maps and drawing up action plans for most of the noise sources. The exception is airports where responsibility lies with the relevant airport operators and in some cases, the Department for Transport.

1.1 Noise mapping for road and rail sources

Maps were made using a new geospatial noise model developed by Defra. This model takes account of the requirements of the new modelling methodology introduced into law since the previous round of mapping. It uses advances in data and technology to calculate noise exposure levels with a higher level of accuracy and coverage than ever before based on information such as traffic flow, road type and road surface data. No actual noise measurements were taken in the production of the strategic maps, as the regulations require mapping to be carried out by means of modelling according to a specific method. This is because sound levels can vary significantly based on factors including weather conditions or the time of day or year, introducing a level of uncertainty into the result. This is averaged out as part of the modelling process.

As a result, mapping data - although useful in helping authorities to identify priority areas for investigation - does not necessarily represent an exact picture of the current situation on the ground at any given locality on any given day.

In previous rounds, major roads, major railways and agglomerations have been mapped. The modelling this time has taken into account all public roads and railways (including light rail) in England. See the regulations for definitions of major roads, major railways and agglomerations.

1.2 Noise action planning for road and rail sources

The data generated by the noise mapping process is used to develop noise action plans, which will be published following a public consultation. Datasets for important areas, or noise hotspots, as well as population exposure figures, will be published along with the action plans.

2. Noise mapping Geographic Information Systems (GIS) datasets

2.1 Rail noise

The rail noise data indicates noise levels according to the strategic noise mapping of rail sources. You should consider the following when reading the data:

• the day-evening-night level (Lden) is a noise indicator for overall annoyance based on annual average A-weighted long term sound over 24 hours - this is with a 5 decibel (dB(A)) penalty for evening noise (7pm to 11pm) and a 10 dB(A) penalty for nighttime noise (11pm to 7am)
• the 16 hour equivalent continuous level (LAeq,16h) is a noise indicator that describes the annual average steady noise level over the 16 hour daytime period (7am to 11pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the day level (Lday) is a daytime noise indicator based on annual average A-weighted long-term sound over the daytime period (7am to 7pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the evening level (Leve) is an evening noise indicator based upon annual average A-weighted long-term sound over the evening period (7pm to 11pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the night level (Lnight) is a night time noise indicator based on annual average A-weighted long term sound over the night period (11pm to 7am) which contains the same sound energy as the actual fluctuating sound across the same period
• the 6 hour equivalent continuous level (LAeq,6h) is a noise indicator which describes the annual average steady noise level over the 6 hour period (midnight to 6am) which contains the same sound energy as the actual fluctuating sound across the same period
• the 18 hour equivalent continuous level (LAeq,18h) is a noise indicator which describes the annual average steady noise level over the 18 hour period (6am to midnight) which contains the same sound energy as the actual fluctuating sound across the same period

Noise levels are modelled on a 10 metre (m) grid at a receptor height of 4m above ground, with a lower threshold cutoff of 35dB for the Lnight and LAeq,6h metrics, and 40dB for all other metrics.

Data is available for all railway sources and those defined as ‘major’ under the regulations.

2.2 Road noise

The road noise data indicates the noise levels according to the strategic noise mapping of road sources . You should consider the following when reading the data:

• the day-evening-night level (Lden) is a noise indicator for overall annoyance based on annual average A-weighted long-term sound over 24 hours with a 5 dB(A) penalty for evening noise (7pm to 11pm) and a 10 dB(A) penalty for night time noise (11pm to 7am)
• the 16 hour equivalent continuous level (LAeq,16h) is a noise indicator which describes the annual average steady noise level over the 16 hour daytime period (7am to 11pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the day level (Lday) is a daytime noise indicator based on annual average A-weighted long-term sound over the daytime period (7am to 7pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the evening level (Leve) is an evening noise indicator based on annual average A-weighted long term sound over the evening period (7pm to 11pm) which contains the same sound energy as the actual fluctuating sound across the same period
• the night level (Lnight) is a night time noise indicator based on annual average A-weighted long term sound over the night period (11pm to 7am) which contains the same sound energy as the actual fluctuating sound across the same period

Noise levels are modelled on a 10m grid at a receptor height of 4m above ground, with a lower threshold cutoff of 35dB for the Lnight metric, and 40dB for all other metrics.

Data is available for all road traffic sources and those defined as major under the regulations.

2.3 Other noise data

Agglomerations data covers urban areas where Defra is required to undertake strategic noise mapping. The same agglomeration boundaries have been used in round 4 as round 3.

Noise action planning important areas data provides a framework for the local management of the ‘important areas’ and is published alongside the action plans.