Gladiatorial games, part 25

(… continued from Gladiatorial games, part 24, posted on 26 Apr 2016).

I mentioned in part 24 that one of the claims that Doug Sharps, expert witness on acoustics for the HS2 Action Alliance, had made to the HS2 Select Committee in defence of his view that more stringent assessment criteria should apply to HS2 operational noise during the evening was that, in contrast to the position with operational noise, the assessment of HS2 construction noise did take this into account (see footnote 1). That this is the case may clearly be verified from HS2 Ltd published documentation (see footnote 2), so it fell to Rupert Thornely-Taylor, acoustics expert witness for the Promoter, to justify why different standards should apply to operational and construction noise. Mr Thornely-Taylor explained to the Select Committee that the “construction noise threshold matrix” that defines time-dependent values for LOAEL (lowest observed adverse effect level) and SOAEL (significant observed adverse effect level) was “traceable back through all the major projects”. He identified the origins of this approach to “a particular concern by Westminster City Council” when the Jubilee Line Extension project was being built, that “there should be a reduction in levels towards the beginning and end of the day” and that this had now become “established practice” (see footnote 3).

He justified the different approach taken for construction and operational noise as follows (see footnote 4):

“The thing about construction noise is it’s of limited duration, as a consequence of which noise levels that are allowed during the daytime are higher than is the case for permanent noise sources from the operation of railways and highways. There is a general acceptance that people are expected, to put it bluntly, to tolerate more noise from construction sites than from permanent installations, because otherwise nothing would get constructed. If they have tolerated more noise during the day, then there is payback, in that the levels in the evening and the shoulder periods are reduced. It would not be appropriate or necessary to do that for a permanent noise source, where the day time levels are lower.”

You may feel, as I do, that this is not a particularly compelling justification, but there it is!

I believe that I am right in claiming the distinction of being the only person who appeared before the Select Committee, other than Mr Sharps, who raised the matter of greater sensitivity to noise in the evening (see footnote 5) – and I had done so almost nine months before Mr Sharps had his turn. The remedy that I proposed was different to Mr Sharps’: I suggested that the Promoter should employ the day-evening-night equivalent level (Lden) in place of the simple daytime equivalent continuous sound level (LpAeq,07:00-23:00). As I explain in my blog How annoying is that? (posted 18 Oct 2012), using Lden automatically applies a 5dB increase to the impact assessment for noise during the evening period.

Such a methodology is very relevant as being a mechanism that fits in with Mr Thornely-Taylor’s concession, as I reported in the final paragraph of part 24, that “you could apportion the 16-hour day with more noise during the day and less noise during the evening”, albeit that Lden uses a 24-hour rather than a 16-hour time period.

Despite this, Mr Thornely-Taylor has made it clear to the Select Committee on more than one occasion that he is not a great fan of Lden (see footnote 6), which is surprising in view of its endorsement by the European Union (EU) as one of its two “harmonised noise indicators” – the other one is Lnight, which is equivalent to the LpAeq,23:00-07:00 metric employed by HS2 Ltd. I guess that, by now, we have become used to the Promoter’s sage having personal opinions that appear to jar with developing international policy. It was hardly surprising, therefore, that he did not treat my suggestion with any enthusiasm.

If you have the time, take a look at the report in the Select Committee transcript of the interchange between Mr Thornely-Taylor and me (see footnote 7). Whilst I will leave you to form your own conclusion about the rights and wrongs of the views that were expressed, I would like to bring to your attention two assertions that Mr Thornely-Taylor made that appear to arise from, if I may be bold enough to claim it, his misapprehensions of the role and significance of Lden.

In the first place he claimed that “using Lden you don’t see the night separately; you see it all lumped into one through that formula and it is less informative and less helpful” (see footnote 8). This is correct, as far as it goes; it is true that Lden covers the full 24-hour period, but the EU requires Lden to be employed “to assess annoyance”. The EU also requires Lnight to be calculated separately “to assess sleep disturbance”, so Mr Thornely-Taylor’s claim appears to be baseless (see footnote 9).

He also claimed that the “LOAEL and SOAEL levels would, of course, change if they were expressed in terms of Lden to take account of the fact that it was a different scale”, implying that the penalty applied in calculating Lden would be nullified by raising the LOAEL/SOAEL thresholds by an equivalent amount (see footnote 10). If this were to be done, then I would agree with Mr Thornely-Taylor’s view that the whole exercise would be pointless, but it is clearly the whole purpose of applying the penalties that are added in calculating Lden that the numerical values of LOAEL and SOAEL are not adjusted upwards to compensate. To do what Mr Thornely-Taylor is suggesting would be equivalent to handicapping a steeplechaser with weights and then reducing the height of the fences that the horse has to jump.

It is something that I deeply regret that I didn’t have the presence of mind early on that January Wednesday morning to challenge the expert on these two points.

I do find some comfort that, in a rare display of respect for a petitioner’s case, Mr Thornely-Taylor conceded that I did “have a point”, but then, in virtually the same breath, he slapped me down with a typical act of condescension, commenting that “it is a very complex topic and it is quite difficult for a non-expert to get his or her mind around it” (see footnote 11).

So that was me put in my place.

(To be continued …)


  1. The evidence presented by Mr Sharps was heard during the afternoon session of the HS2 Select Committee that was held on Monday 12thOctober 2015 (video and transcript).
  2. Table 1 in Appendix A to HS2 Ltd publication High Speed Two Information Paper E23: Control of construction noise and vibration prescribes different values of LOAEL and SOAEL to apply for particular time periods during the day/evening, with the lowest values being specified for the period 19:00 to 22:00.
  3. See paragraph 289 of the transcript of the afternoon session of the HS2 Select Committee held on Monday 12thOctober 2015.
  4. See paragraph 290 of the transcript of the afternoon session of the HS2 Select Committee held on Monday 12thOctober 2015.
  5. See paragraph 16 of my Commons petition 0985.
  6. For example, see paragraph 47 in the transcript of the morning session of the HS2 Select Committee held on Tuesday 8thJuly 2014.
  7. The exchange is reported in paragraphs 157 to 169 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 21stJanuary 2015.
  8. See paragraph 158 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 21stJanuary 2015.
  9. See item 9 in the preamble to EU Directive 2002/49/EC.
  10. See paragraph 164 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 21stJanuary 2015.
  11. See paragraph 169 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 21stJanuary 2015.

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

Important Note: The record of the proceedings of the HS2 Select Committee from which the quotes reproduced in this blog have been taken include 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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