undertook production of the strategic noise maps under a single. Vertical edges are only considered when you are in the shadow of the barrier. For R2 strategic noise mapping England, Wales, Northern Ireland, Scotland and Malta each. This model only accounts for such a situation along the top edges. ISO9613-2 considers the effect of edges that are not screening, for example an observer looking over the top of a wall. In complex models, applying this recommendation will improve calculation times considerably. ISO17534-3 recommends that lateral paths are limited to vertical edges within the range of the most distant horizontal edge multiplied by 8, with respect to distances from the direct source-to-receiver line. The lateral path method can be configured to only consider "convex" paths that curve in a single direction and do not zig-zag.Ĭonvex path illustration Limit distance (ISO recommendation) Illustration of the inclined source-to-receiver plane Convex path option When enabled, lateral paths around vertical edges are found within a flat plane inclined along the direct source-to-receiver line. It is recommended that you highlight where these simplifications have taken place. For each simplification there will be a degree of error added to the model. The following table of accuracy is taken from ISO9613-2 based on tests without screening or reflections Average height of source and receiverĬomputer modelling requires a simplification of real-world conditions into basic components. It is essential to consider that modelling is only ever an estimate and real-world measurements may differ greatly. Alternatively, the average of varying meteorological conditions over months or years.įor more information about the calculations and their limitations, refer to ISO9613 parts 1 and 2.The results represent the approximate average noise energy due to transportation noise sources over a 24-hour period at the receptor locations where noise is computed, expressed in decibels. A moderate ground-based temperature inversion, such as is common on clear, calm nights should not significantly affect accuracy. The END requires Member States to produce strategic noise maps every five years, designed to show the number of people exposed to various levels of. The national transportation noise map is developed using a 24-hr equivalent A-weighted sound level (denoted by 24-hr LAeq) noise metric.Wind speed between approximately 1-5 m/s, measured 3-11 m above the ground.This is defined as a wind direction within an arc of 90 degrees with the wind blowing from source to receiver. Below are suitable conditions taken from ISO9613-2. Sound propagation is affected by variations in meteorological conditions. not floating above the ground or with empty sections / perforations. Screens are flat with no significant transmission of sound through or under the screen.The ground is of a continuous type (a single ground factor).Noise sources behave as a point (or line for line sources) and are far-field, where inherent directivity is minimal.The round 1 and round 2 noise maps can be viewed on an interactive web app via the link below. agglomerations - urban areas with more than 100,000 inhabitants, taking into account the above sources and additionally, other roads, railways, aircraft movements and industrial premises.major airports - airports with more than 50,000 movements annually.major railways - railways with more than 30,000 train passages annually.major roads - roads with more than 3 million vehicle passages annually.Round 2 noise maps have been produced based on 2011 data for the following sources: Noise is defined as a nuisance in law if it causes injury, is likely to cause injury, or interferes unreasonably with someones personal comfort or enjoyment. agglomerations - urban areas with greater than 250,000 inhabitants, taking into account the above sources and additionally other roads, railways, aircraft movements and industrial premises.major airports - airports with more than 50,000 aircraft movements annually.major railways - railways with more than 60,000 train passages annually.major roads - roads with more than 6 million vehicle passages annually.In compliance with the Environmental Noise Directive ("END") four round one strategic noise maps for Northern Ireland have been produced estimating noise levels from the following sources: