A very noisy bird, part 2

(… continued from A very noisy bird, part 1, posted on 22 Aug 2015).

In his evidence to the HS2 Select Committee, acoustics expert Steve Summers identified two particular “non-residential receptors”, to use the somewhat sanitised language of the HS2 Phase 1 Environmental Statement (ES), where he regards the operational noise levels predicted for HS2 as a cause for concern (see footnote 1).

The first of these is St Mary’s Church Wendover, a Grade II*-listed building, where Mr Summers revealed the predicted noise level from train pass-bys to be 70 dB LpAF,max outside the church, which he described as “high”. He said that he estimated that this would mean that the resulting level inside the church would be “in excess of 40 dB, probably up to 46 dB LAmax, and would be “likely to cause disturbance to concerts as well as other services or activities” (see footnote 2).

The second sensitive site singled out by Mr Summers was Wendover Campus School (aka Wendover House), a mixed special school. He told the Committee that the predicted noise level of train pass-bys outside the school is 71 dB and that this was “likely to equate to internal levels, allowing [for] windows and open ventilation, of between 56 and 61 dB, which is likely to cause disturbance to teaching and learning when windows are open” (see footnote 3).

In his cross-examination of Mr Summers, Tim Mould QC, Lead Counsel for the Promoter, asked him to consider three exhibits that had been prepared by HS2 Ltd.

The first of these P7494(2) displays the results of noise measurements taken inside St Mary’s during evenings when no events were taking place in the church (see footnote 4). Mr Summers observed that there was an error in that exhibit (see footnote 5); he indicated that the green bar at 40 dB should show 36 events, not 18, as this was the maximum number of train pass-bys. He was actually wrong about this; as I will explain in part 3, the bar chart is correct, as far as it goes.

The point of Mr Mould showing this exhibit to Mr Summers was to enable the QC to claim that “the [pass-by noise from] railway trains will be well within [the] existing range of noise levels [inside the church]” (see footnote 6).

Mr Mould made a similar claim for the pass-by noise predicted for some outside assessment locations “within and on the edges of the settlement of Wendover”, illustrated by exhibits P7499(1), showing the existing baseline noise level at these locations, and P7499(3), showing the predictions of impacts and effects due to operational noise (see footnote 7). Based upon these exhibits he put it to Mr Summers that a pass-by of a HS2 train will be “a new noise event, but it will not increase the peak noise experienced (sic) that people have within the settlement of Wendover” (see footnote 8).

There was some discussion that can cast some light on these claims by Mr Mould during Mr Summers’ cross-examination and subsequent re-examination by Nathalie Lieven QC. This discussion was initiated by a question posed by Mark Hendrick MP. He asked (see footnote 9):

“Where is the current noise coming from?”

Mr Mould suggested that the existing peak noise events that HS2 Ltd’s sound level meters had picked up were the result of (see footnote 10):

“Traffic, existing railway trains, people shouting in the street, all the things that make up the noise of existing life in a successful market town.”

But it was the suggestion from Mr Summers of another possible noise source that serves as a warning to treat measurements made with a sound level meter with caution; he suggested “a bird”, to which Ms Lieven added “a very, very noisy bird” (see footnote 11) – I told you in part 1 that ornithology would come into this tale!

The whole point is that it needn’t have been a noisy bird at all, it could just have been a fairly quiet bird perched on top of the sound level meter! You see, sound level meters can’t distinguish loud sounds a distance away from softer sounds close to; they can both register the same sound pressure level at the meter, which is all that gets logged.

The other thing that sound level meters are hopeless at doing is distinguishing an awful din, like a high-speed train passing, from a pleasant sound like, err, birdsong.

Mr Summers also provided a practical example of why the type of data that Mr Mould was basing his case on needed to be treated with caution (see footnote 12):

“I think [Mr Mould’s proposition that noise from the railway is broadly speaking within the range of the existing noise environment is] a very simplified view because obviously properties that are next to an existing road which has got a fair amount of traffic will have a high LA max, whereas other properties which are distant from the major roads will have a very low existing LA max.”

So I think that Mr Mould was probably on a bit of a sticky wicket with his claim of “much the same, only more of it”. He looked even more out on a limb when Mr Summers pointed out to him that for some of the locations shown on P7499(3) “the predicted maximum noise levels for HS2 are above the baseline LA maxes” (see footnote 13).

I think that his entry on the scorecard for this particular innings should be “T Mould – retired hurt” as he limped off covering his exit with (see footnote 14):

“All right. I’m happy with that. That’s the point I want to make. Thank you.”

(To be concluded …)

Footnotes:

  1. Mr Summers’ evidence was given during the public session held by the HS2 Select Committee on the afternoon of Tuesday 14thJuly 2015. The relevant passage is recorded from paragraph 165 of the transcript and may be viewed from 14:49 hrs in the video of the session.
  2. See paragraph 168 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  3. See paragraph 172 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  4. Mr Mould’s confirmation that measurements were made when the church was not being used for events is recorded in paragraph 172 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015. It is also repeated in paragraph 192.
  5. See paragraphs 193, 227 and 228 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  6. See paragraph 192 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  7. Both exhibits are included within the exhibit pack for 14thJuly 2015; P7499(1) is page 87 of the pack and P7499(3) is page 88. P7499(1) uses data from Table 1 in Appendix SV-002-010 to Volume 5 of the ES. The figures displayed in P7499(3) are culled from the data in Table 3 in Appendix SV-004-010 to Volume 5 of the ES.
  8. See paragraph 200 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  9. See paragraph 201 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  10. See paragraph 204 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  11. See paragraphs 224 and 225 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14thJuly 2015.
  12. See paragraph 216 in the transcript of the afternoon session of the HS2 Select Committee held on Tuesday 14th July 2015.

Important Note: The record of the proceedings of the HS2 Select Committee from which the quotes reproduced in this blog are taken is an uncorrected transcript of evidence, which is not yet an approved formal record. Neither witnesses nor Members have had the opportunity to correct the record in such instances, and it may therefore be subject to changes being made in the light of any such corrections being requested.

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