Methods & Personnel
Planning Guidance on Noise
It is usual to assess noise affecting the site of proposed residential development, as prescribed in The Scottish Executive Development Department publication Planning Advice Note 56 Planning and Noise (PAN56). The procedures set out in this document are used in relation to road traffic, railway, aircraft and industrial noise, whereas that from industry, restaurants, pubs, night-clubs and mechanical services plant is dealt with slightly differently.

PAN56 stipulates that transportation noise be considered over two periods, daytime from 07.00hrs to 23.00hrs, and night-time from 23.00hrs to 07.00hrs. The measured noise level determines which of 4 Noise Exposure Categories (NEC) the site falls into. Each NEC is accompanied by a series of recommendations ranging from; “Noise need not be considered as a determining factor in granting planning permission, although the noise level at the high end of the category should not be regarded as a desirable level”, for NEC A, to “Planning permission should normally be refused”, for NEC D.

PAN56 also specifies internal noise level limits of a day-time equivalent continuous noise level, LAeq (07:00hrs to 23:00hrs), of 45dB(A), and a night-time one of LAeq (23:00hrs to 07:00hrs) of 35dB(A). With the results of the measurements of the noise, together with details of how the houses/flats will be constructed, we can calculate what level of noise will exist inside them, for comparison to the 45dB(A) and 35dB(A) limits.

Method of Measuring Traffic Noise
It is extremely rare for a council to request that a full 24-hour noise survey be carried out. The daytime levels can be calculated very accurately based on measurements of the noise made over 3 consecutive one-hour periods. Details of this measurement technique are set out in the Department of Transport document titled Calculation of Road Traffic Noise. Charlie Fleming Associates usually measures the noise over a three-hour period and calculates which NEC the development site falls into based on the results. It is generally accepted that the night-time noise falls into the same category, or that it is 10dB lower than the day-time level. We have used this technique before all over Scotland, and indeed once in England, and the results have always been accepted by the local authority’s officers.

Method of Measuring Railway Noise
As with traffic noise, it is very rare that a council officer insists that the railway noise be measured over 24 hours. It is usual to measure the noise of the passing trains over a shorter period and then to calculate, using a procedure set out in the Department of Transport document titled Calculation of Railway Noise, together with timetabling information from Network Rail, the likely level over the 16-hour daytime period. The results of the measurements are then also used to calculate the 8-hour night-time noise level. This technique is also accepted by Scotland’s local authorities.

Method of Measuring Railway Vibration
With respect to vibration from railways, PAN56 refers to BS6472 Evaluation of human exposure to vibration in buildings (1Hz to 80Hz). It is usual to measure the vibration of the trains, in accordance with this standard, over the same 2 to 3 hour period that the noise is being measured. What is known as the vibration dose value can then be computed from these results and the timetabling information, in much the same way as the daytime (07.00hrs to 23.00hrs) noise level. The day and night vibration dose values can then be compared to the criteria for human perception given in BS6472. This approach is accepted by local authority planning officers in Scotland.

Method of Quantifying Aircraft Noise
British Airports Authority monitors the noise around its sites continuously, and produces what are called noise contours from the results. Using the contours to determine which NEC the development site falls into, is far more accurate than using the results of measurements made over a few hours, or even days, and so this is the approach we adopt.

Method of Measuring Industrial Noise
As noise from factories and industrial production plants varies with time, it has to be measured over a period which will encompass the different levels. A period of 4 hours is usually long enough to build up a good picture of how the noise varies, and it this measurement period that we usually adopt. In any event, it is very unlikely that the planning officer will accept a shorter measurement period.

Sometimes local authority officers ask for assessments of industrial noise to be carried out to British Standard 4142: 1997 Method for Rating industrial noise affecting mixed residential and industrial areas (BS4142). We try to discourage the use of this standard because it almost invariably concludes that the noise will lead to complaints. We present strong arguments against its use, primarily because its conclusions are based on the background noise to which the residents are exposed, and, when new residential development is proposed, we do not know what this is. (BS4142 is appropriate for new industrial premises proposed adjacent to existing housing).

Method of Measuring Construction Site Noise
This, being temporary, is not usually of concern to the planning officer. Occasionally, on long term projects, such as the repair work on the Forth Bridge, it is necessary to consider it. In this case we measured the noise and dealt with it in the same way as we would deal with any other industrial noise.

Method of Measuring Noise from Pubs and Night-clubs
The noise emanating from pubs and night-clubs varies according to what is taking place within the establishment. Live entertainment usually generates the greatest noise, and so it is necessary to measure it when a band, or karaoke is on. The noise of licensed premises also has to be measured when the premises are busy, and hence noisy, which is usually on a Friday or Saturday night. As the noise usually increases in level as the evening progresses, it has to be measured between around 22:00hrs and whenever the premises close.

Rather than using the limits set out in PAN56, virtually all local authorities in Scotland apply a criterion known as inaudibility to this type of noise. That is, that the entertainment noise must not be audible in the proposed houses/flats. Having calculated the level of noise likely inside the proposed dwellings, we compare this to the threshold of hearing/ limiting level of audibility.

Method of Measuring Mechanical Services Noise
As mechanical services noise does not, generally, vary much with time, it can be measured relatively quickly, over an hour or so. (Sometimes we do have to wait for a condenser to cut in, boiler to fire up, and so on).

Rather than using the limits set out in PAN56, virtually all local authorities in Scotland apply a limit of noise rating (NR) 35 to this type of noise during the day, and NR25 to it at night. Having calculated the level of noise likely inside the proposed dwellings, we compare this to NR35 or NR25 as appropriate.

Measurement Position
A single measurement position is usually sufficient, in all but the largest development sites, or ones with more than one noise source affecting them. The position selected is the one in which the most exposed house or flat will be built. The principle in this is that, if the noise is acceptable at the most exposed house, it follows that it will also be acceptable at the other, less exposed ones. In any event, the planning officer will not accept the results of measurements made on quiet parts of a development site, away from the noise source in question.

Instruments
We use only Brüel & Kjær instruments. These are the “Rolls Royce” of acoustical instrumentation and give more accurate results than that used by some of our competitors. This is important as inaccurate readings can lead to you having to incorporate expensive noise control measures in the houses, or site layout, which may not, in fact, be necessary.

Few, if any, firms in Scotland have the equipment necessary to measure railway vibration properly. We use Brüel & Kjær instrumentation which was specifically designed for work to BS 6472 and is widely held to be the best available on the market.

Personnel
Noise measurements are made by either Charlie Fleming or Peter Hubbard. Other companies may leave their instruments supervised by a technician or person with no knowledge of acoustics. (Peter has an honours degree in acoustics and several years experience in environmental noise). Analysis of the results and calculations are usually carried out by Peter, supervised by Charlie. The report is prepared by Charlie.

From start to finish your planning application is dealt with by experienced, highly qualified acousticians. Some other companies do not have this experience and the consequences of this are outlined in Why Choose Charlie Fleming Associates?