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Calculation of SiteNoise
Calculation of noise from Industrial sites, minerals extraction sites, civil engineering works and similar types of activity is perfectly feasible, but it is more complex than calculation of noise from a road or railway.
The main reason is that the noise sources on such sites are highly variable, in type, in location and in time.
Industrial sites can be distinguished from minerals or civil engineering sites, since on industrial sites, much of the activity will arise from fixed plant within buildings, whilst minerals and civil engineering sites generally involve the use of mobile plant in the open air. There is, of course, some overlap, as deliveries and materials storage on industrial sites often involves the use of vehicles and equipment outdoors, whilst civil engineering and minerals sites can involve fixed plant within buildings.
The main issue with industrial sites is the huge variety of plant involved, for which the sound emission levels are probably unknown. This is made more difficult because the sound emitted from the site will also depend on the sound insulation properties of the buildings that house the plant. The EU Good Practice Guide on Noise Mapping gives some generic guidance on the typical sound power emitted from various types of industry, in terms of watts per square metre. This may be adequate for ‘strategic’ noise assessments, but will not be adequate for most planning or nuisance assessments.
For minerals and civil engineering sites the problem is different. The type of plant is likely to come from a fairly limited range – such as earth-moving, rock-breaking, excavating, piling, concreting and similar operations, which have been reasonably well studied. The problem is that the location of the plant can change rapidly, both in plan and elevation, such as when deep open-cast mineral extraction is taking place.
Atkins’ SiteNoise software is based on guidance given in British Standard BS 5228: Part1: 1997 ‘Noise and vibration control on construction and open sites’. Such sites generally use diesel-engined plant which means that the frequency spectrum is fairly well known and similar to that of roads. It is not therefore necessary to undertake frequency analysis of the source and propagation characteristics of the site, which greatly simplifies the calculations (and also reduces one element of uncertainty).
BS 5228 envisages three types of noise source – Static, mobile on site, and haul roads. Static plant is located at a defined position and does not move. Mobile plant on site is plant that moves within a small area, for example and excavator moving material a short distance from a stockpile to a processing plant. The movements are frequent, but irregular. Haul roads are essential movements along a defined track that can be specified in terms of a number of movements per hour and with a speed that can be typified.
SiteNoise allows each of these types of source to be defined and positioned anywhere on the site map.
To use SiteNoise, you will require a map of the site, a list of the plant to be used, and a description of the ‘activities’ on site – in other words the work processes that are involved. The map will need to show the location of the site activities (such as the location of static plant, haul roads and ‘mobile’ activities). You will also need height information, particularly for activities that will take place at a height above ground level and in excavations below ground level. You will also need information on the ground topography, especially on the height of noise barriers, noise control bunds and fences and baffle banks.
If these are available as digital drawings, then you will probably be able to convert them directly into SiteNoise model objects. If not, you may have to scan your map in and then trace over it on screen. SiteNoise has functions that let you add a height to objects if the original mapping is in two-dimensions.
When you have created your topographical model, you will need to put in the working locations, such as the locations where fixed or mobile activities will take place. The final step is to allocate plant to the actual working locations. In SiteNoise, this is called creating ‘Activities’.
Once you have done this, you can then start noise calculations, either creating noise contour maps or calculating noise at specific receiver locations that you have entered.
The modelling process is done from a CAD-style graphical user interface. You do not need to have a detailed understanding of the noise calculation process in order to create a noise model: the requirement is to enter the physical location of objects that are important to the generation and propagation of noise. SiteNoise does all the geometrical analysis for you.
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