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All content are opinions and objections that were raised as part of the response to Msport planning application to Allerdale planning ref 2/2014/0350. If you have any comment or disagreement then first realise that opinion is just that, opinion in a public planning process. You may email factual errors to Contact @ dovenbynoise.info
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M-SPORT RACE TRACK, DOVENBY
Review of Draft Noise Management Plan
As requested, following our recent discussions and email exchanges, please see below regarding the Noise Management Plan (NMP) submitted by Northern Developments.
The NMP is required to satisfy condition 6 of the planning consent for M-Sport’s evaluation centre, part of which involves the construction of a motorsport test track. The condition was varied to include very specific details of elements to be included in the NMP, notably the inclusion of 5 minute (LAeq,5min) and maximum (LAmax) noise level controls as well as the hourly averages previously proposed.
Some elements of the analysis below are technical in nature. They are summarised in this letter in the interests of legibility and ease of reference, but can be supported by more detailed analytical submissions as required. It is important to state at the outset that, in its current form, the NMP is demonstrably flawed, it should not be agreed by the planning authority and any such agreement, if it were to be made, would be exposed to further challenge.
LAeq 5mins Control Levels
In their submission entitled “Setting Maximum Noise Level Control” Northern Developments seek to justify the 5 minute control levels selected in the NMP, specified by Justice Holgate to impose additional control.
However, at 11 decibels more than the hourly control levels in each case, these are literally the highest values it would be possible to set for the 5 minute control levels. Any higher would break the one hour limit in which the 5 minutes in question occurred, regardless of the activity in the remaining 55 minutes. This provides no additional control over louder short duration activities as the justification document suggests, and this assertion is confused at best, if not disingenuous.
A reasonable level at which to set the 5 minute control would be one which allows for a slight increase above the level allowed for the full hour, recognising the inevitable vagaries of short term level fluctuations, while providing additional restraint and protection against significantly noisier short bursts of noise. In that context a level 5 decibels above the 1 hour value would seem to me to be the highest value which could be described as satisfying this requirement.
Lmax Control Levels
The maximum noise level restriction was also set by Justice Holgate to provide additional control over short term annoyance which is not captured by hourly averages.
The descriptions of time weighting in the justification document are confused and misleading, and the term ‘fast max’ appears to have been derived specifically to suggest that this provides a more stringent control, when use of the fast time weighting is generally the default setting (as reference to the World Health Organisation guidance confirms).
1 Also see Appendix A, Association of Noise Consultants Guidelines: Environmental Noise Measurement Guide 2013
Comparisons to other Lmax guidance values related to sleep disturbance at night are irrelevant, the annoyance and consequent degradation of amenity during the day being more related to noise experienced externally – in the garden for example, rather than those capable of waking neighbours internally.
As used in the 5 minute suggestion, the Northern Developments justification document seeks to suggest initially that all of the noise consented during a whole hour should be compressed into a single maximum event, allowing it to be up to 100dB. Other than the technical flaw in this calculation (the ‘fast max’ cannot be calculated in this way, they are effectively referring to an LAeq,125ms), the argument is irrelevant as the proposed activity (cars using a test track) could never be configured to emit noise over only 0.125 seconds in each hour.
The suggestion that the applicant set out with the objective of reducing the sound power of this ‘consented’ Lmax level by a factor of 200, and its perceived loudness by a factor of 5 is a somewhat bizarre and effectively meaningless concept especially as it is a reduction from an illogically derived value in the first instance.
A much better approach is described in the third element of the applicant’s analysis, which refers to comparisons with existing background maxima. Consideration of the extent to which proposed maximum event noise levels would intrude compared with other sources of intrusion is more logical, and should form part of this assessment.
A more comprehensive implementation of this approach would involve both frequency of occurrence and range of values, whereas only the range is considered. Also, troublingly, although the range of values at each location is apparent from the tabulated data in the justification document, the range reported in the summary is only the range of the highest values at each position. This suggests the range of maxima in the community can be summarised as between 78 and 88.1 dB LAmax whereas the true range of the data was 48.6 to 88.1 dB LAmax.
Using the same comparative expressions as the applicant, this over-estimates the bottom range of community LAmax value by a factor of 870 times the sound intensity, equivalent to 8 times the subjective loudness.
Finally, a single value is proposed for the Lmax control value. This is inconsistent with the logic of the remainder of the submissions, which advocate a balance between level of disturbance and frequency of occurrence. It can only follow that three Lmax limits are required – one for each of categories A, B and C.
Suitable complementary values which would be consistent with control of community noise levels in the context of both ambient conditions and the three noise level categories would need to be defined, but should be based on considerably more survey data than hourly values from a few hours at each location on a single day to provide a meaningful statistical description of typical prevailing background conditions.
The applicant describes a process by which a fixed relationship is established, and assumed to be universally applicable, based on a single trackside monitor at 10m from a designated point on the circuit. Experience from other circuits has given me considerable insight into the difficulties inherent in establishing such a fixed relationship. Different vehicles will have different noise characteristics, manifested differently around the track, making the selection of a single point which is truly representative of all noise emitted from the impossible, especially when the track is used by a variety of vehicles.
Moreover, day to day variations in weather conditions will mean that delivering compliance with an off-site community noise control target by trackside monitoring alone requires the trackside threshold to be set to cater for the worst case – likely to be overly restrictive on other, less adverse days in terms of weather.
I would advocate at least two monitors, possibly three, located further from the track possibly close to the site boundary, at locations which would still capture, and be dominated by noise from the track when in use, but with a greater field of ‘view’ of the track. This would render them less sensitive to local variations in noise output around the track and partially account for differences in weather conditions. Closer monitor locations at 10m or sometimes 20m are useful on competitive circuits, and those used for track days, to differentiate between vehicles and identify which are being unreasonably noisy, but with the level of operational control and function as a test track in the case of M-Sport, this appears to be less relevant.
I trust the above provides sufficient clarity. I’d also like to confirm that, if convenient and appropriate, I’d be more than happy to provide more detailed direct assistance to M-Sport and their acoustics advisors, in developing the noise management plan and establishing workable monitoring arrangements.