This might lead to annoyance

In this blog I will take up where I left off in Putting us on the map (posted 28 Feb 2014) by continuing my exploration of table 1 in Report SV-004-017 in Volume 5 of the Environmental Statement (ES).

The second block of three columns in table 1 is headed “Do nothing (Opening year baseline)”. The levels listed here are those that HS2 Ltd predicts will result from “the sound environment that would exist in 2026 without [HS2]” (refer to paragraph 3.2.1 of Report SV-004-017). For the cluster of six houses that includes chez moi (ID213490) the table predicts the day equivalent continuous sound level (LAeq,T) will be 59dB and the night measurement will be 47dB. This was something of a shock. It means that, according to HS2 Ltd, even if HS2 doesn’t get built my noise environment will, by 2026, be above World Health Organisation (WHO) recommended levels. According to the WHO, in order to “protect the majority of people from being seriously annoyed during the daytime, the sound pressure level on balconies, terraces and outdoor living areas should not exceed 55 dB LAeq”. Also the WHO guideline level outside a dwelling for the “protection of public health from night noise” is 40dB LAeq. So, if I believe HS2 Ltd, just outside my house the daytime noise will be 4dB more than seriously annoying and at night will exceed the WHO guideline designed to protect my health by 7dB.

The culprit appears to be the road that passes the end of my cul-de-sac. The receptor location is about fifty metres from the centreline of this road and is close to the 30mph limit signs that mark the start of the built-up area through Cubbington; prior to reaching these signs the speed limit is 50mph. Twice a day, this single-carriageway road, which is classified a B road, carries commuter traffic, but most of the time traffic is more sporadic than heavy. I have never found traffic noise from this road to be particularly annoying, nor does it disturb my sleep, even in summer with the bedroom window open. I was, accordingly, somewhat surprised by the noise levels forecast by HS2 Ltd and wondered how the prediction had been obtained.

For the source of this prediction we have to refer to yet another of the ES Volume 5 reports. For my community forum area the relevant report is SV-002-017 – you can access the reports for other areas here.

In this report there is also a table 1 to which we must refer. This tabulation includes an entry for receptor ID213490 that tells us that the “existing baseline sound level” for 2012/13 is 58.8dB LpAeq,16hr (i.e. day) and 46.7dB LpAeq,8hr (i.e. night) – so, according to the ES, I don’t have to wait until 2026 as I am already suffering noise levels above WHO guidelines. These figures are derived from measurements made in the locality; the table cites “measurement location” CN028L as the source of these measurements. The suffix “L” indicates that the measurement site was employed to make long-term measurements, with the sound meter running unattended for a period of several days. The location of this measurement site is indicated by the red letter “B” on the map that I included in my blog Putting us on the map and which I have repeated below for convenience.

Noise prediction and measurement locations in east Cubbington (Source: HS2 Ltd)

Noise prediction and measurement locations in east Cubbington (Source: HS2 Ltd)

The entry for ID213490 in table 1 also includes the “data source coding” string “1,C,i,c”. Table 2 provides a key to allow us to interpret this string, as follows:

  • “1” confirms that the prediction is based on data from a long-term measurement location.
  • “C” indicates that a correction has been applied for distance of the receptor from the measurement location.
  • “i” indicates that the data are from a measurement location “at or very close to” the receptor location.
  • “c” implies that the “data are considered to be an estimate of the sound climate (e.g. taken from Defra noise maps, etc.)”.

Some additional explanation of the codes is given in Annex B paragraph 1.39 to paragraph 1.3.37 in ES Volume 5 Appendix SV-001-000. From this explanation it is clear that the data from a long-term measurement location, as employed for ID213490, rate as the best quality possible, but that the measured data are only representative if the soundscapes of the measurement location and the receptor location are similar. The ES seems to be in some doubt about this, as witnessed by the attribution of the code “c” to the data source coding string for ID213490.

I am also not very sure about the inclusion of the code “i” in the data source coding string for ID213490. The meaning of “at or very close to” is somewhat subjective, but taking a ruler to the ES maps, the measurement and receptor locations are some 450 metres apart, so I think that the description is stretching things somewhat.

The inclusion of code “C” in the data source coding string tells us that the data have been adjusted as the measurement location and receptor location are different distances from the source of noise, which is the road in this case. Whilst the maps in the ES do indicate that the receptor is closer to the road than the measurement location, perhaps half the distance or slightly more, I can find no information in the ES on the extent of any adjustment that has been applied to the measured data.

I will conclude my assessment in the next posting.

Acknowledgement: The Ordinance Survey mapping upon which the noise contours, route design and receptor locations are overlaid has been reproduced in accordance with the principles of fair dealing as set out in the Copyright, Designs and Patents Act 1988.  On this basis, this mapping is:

Reproduced by permission of Ordnance Survey on behalf of HMSO.

© Crown Copyright. All rights reserved.


One response to this post.

  1. Posted by chriseaglen on March 4, 2014 at 5:32 pm

    Hopefully you will explain this in regard to questions 1 and 2 of the Environmental Audit Committee inquiry to be submitted before the end of the 7th March 2014 please. Otherwise it is simply an observation instead of an example of shortcomings that justtify the need to have proper local technical inquiries and to verify for MPs these details that most would not understand in practice. Thank you


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