Gladiatorial games, part 16

(… continued from Gladiatorial games, part 15, posted on 18 Feb 2016).

Before finally setting aside Chiltern District Council’s (CDC) exhibit A1571(59) I want to report a comment made by the Promoter’s acoustics expert witness, Rupert Thornely-Taylor. Under cross-examination Mr Thornely-Taylor appeared to pick up on something that I noted in footnote 12 to part 12 of this blog series; that the guidance given in the table in paragraph 005 on the Planning Practice Guidance (PPG) website is “based on the likely average response”.

He was asked by CDC’s counsel, Gwion Lewis, what his understanding was “of the point at which annoyance commences”. His reply ended with the sentence (see footnote 1):

“So, there is no single answer to the questions Mr Lewis is asking me, I could only answer them in terms of some British standard human who happens to lie on the median, of the distribution curve.”

Referring to the cumulative distribution function (CDF) curves presented in A1571(59), Sir Peter Bottomley remarked that this meant that “you’ll be up at a noise level of about 62” (see footnote 2); Mr Thornely-Taylor agreed. Sir Peter continued:

“So we aren’t actually looking at the average, we’re looking at a time when a smaller number are significantly disturbed, I think.”

In fairness to Mr Thornely-Taylor, I don’t think that he was seriously proposing that his “standard human” interpretation of the PPG caveat was necessarily the correct one; after all, HS2 Ltd is proposing a LOAEL (lowest observed adverse effect level) threshold set at 50dB LpAeq,16hr. But, his comment does raise the pertinent question of, “just what does ‘based on the likely average response’ mean?”. Unfortunately, this was not a matter that the CDC’s expert witness, Rick Methold, had addressed when he gave evidence that preceding morning, so we don’t have the benefit of his view.

From what I witnessed viewing the Parliament TV coverage of the events that November day, the whole question of the interpretation of the PPG table is a bit of a puzzler (see footnote 3). Even Mr Methold and his client’s counsel didn’t appear to be singing entirely from the same song sheet on the question of how to recognise the point at which the noise level passes the threshold between non-intrusive to intrusive noise, which the PPG has as LOAEL.

According to Mr Methold, LOAEL “must be the point at which annoyance starts to occur” (see footnote 4). According to Mr Lewis, when cross-examining Mr Thornely-Taylor, “the LOAEL can’t be set at a point when we start to observe annoyance” (see footnote 5). Mr Thornely-Taylor, on the other hand, appeared to be trying hard not to venture an opinion on this tricky topic; he laconically ventured that the necessary approach to the PPG was to “just read it for what it says” (see footnote 6).

So, all in all, the Committee’s proceedings did not bring us very far in our search for a definitive answer to the metaphysical problems of how intrusion relates to annoyance and how to address the variation in noise tolerance across the population. Whilst it may be, to some extent, understandable that the rough and tumble of a quasi-judicial process would fail to provide little, if any, enlightenment on this matter, I find it totally inexcusable that, as far as I can see, the Environmental Statement (ES) fails to address and discuss the requirements of the PPG; I presume that, had such a discourse been provided, then it would have been contained with the Volume 5 Appendix SV-001-000, but I can find no reference to this matter therein. Since the PPG is a key element of the suite of documents that define UK policy on noise, I find it astonishing that HS2 Ltd has failed to address the interpretation of its requirements in the ES, and consider it tantamount to a failure to demonstrate that due diligence has been exercised.

Perhaps the reason for this glaring omission may be understood from Mr Thornely-Taylor’s summary of his position (see footnote 7):

“I’m simply saying that if you try to consider whether intrusive equals annoyance, and things like that, you’ll get into difficulties.”

Well, we wouldn’t want that, would we?

(To be continued …)


  1. See paragraphs 104 and 105 of the transcript of the afternoon session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015.
  2. The exchange is recorded in paragraphs 106 to 108 of the transcript of the afternoon session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015. It would appear that Sir Peter Bottomley was referring to the “little annoyed” response curve; in any case he appears to have misread the %LA CDF curve, because the median point on that curve (i.e. corresponding to 50 per cent of the population) is actually 66.5dB Lden. The equivalent points on the other two CDF curves are both above 75dB Lden, outside of the range covered by the CDFs.
  3. The evidence presented on behalf of CDC occupied the whole of the morning session held on Wednesday 4thNovember 2015 (video) and the Promoter’s response, including evidence from Mr Thornely-Taylor, was given in a shorter than usual afternoon session (video).
  4. See paragraph 96 of the transcript of the morning session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015. Mr Methold did, however, also acknowledge that “you could have some intrusive noise that doesn’t elicit annoyance.
  5. See paragraph 113 of the transcript of the afternoon session of the HS2 Select Committee that was held on Wednesday 4th November 2015.
  6. See paragraph 112 of the transcript of the afternoon session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015.
  7. See paragraph 126 of the transcript of the afternoon session of the HS2 Select Committee that was held on Wednesday 4thNovember 2015.


I wish to thank Michael Woodhouse for his suggestions and comments, which I have found invaluable in preparing this series of blogs.

Exhibit A1571(59) has been extracted from the bundle of evidence submitted to the HS2 Select Committee by Rick Methold and published on the website of the HS2 Select Committee.

Important Note: The record of the proceedings of the HS2 Select Committee from which the quotes reproduced in this blog have been taken are uncorrected transcripts of evidence, which are 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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