Gladiatorial games, part 22

(… continued from Gladiatorial games, part 21, posted on 14 Apr 2016).

The main problem with getting the HS2 Select Committee to appreciate that there could be noise issues when HS2 is running, is the apparent perception amongst its Members that there isn’t a noise problem with HS1 and, ergo, there shouldn’t be one with HS2 either. This sentiment has been expressed to petitioners appearing before the Committee on a number of occasions, mainly by the Chairman. Indeed, Mr Syms told Rick Methold, the expert acoustics witness for Chiltern District Council, that Members of Parliament that represent Kent constituencies “say that they don’t get many complaints at all”. He conceded that the construction phase had been “difficult”, but that the noise from train operations was something that “people don’t really notice that much” (see footnote 1).

A number of petitioners have sought to dispel this perception by pointing out some essential differences in nature between HS2 and its HS1 forerunner. For example, Doug Sharps, the expert witness who appeared for the HS2 Action Alliance (HS2AA) in October last, identified these differences as (see footnote 2):

  • Unlike HS2, the HS1 route follows existing transport corridors, so there is “an enormous difference in the existing noise climate”. Mr Sharps told the Committee that “background and ambient noise levels [for HS1] are in excess of 50dB for probably about 85% of the route”, whereas the background noise level at the seventeen villages and towns along the HS2 route that he had surveyed was around 30 to 35dB.
  • The planned train frequency for HS2 is “much greater” than on HS1.
  • It is planned that HS2 trains will start earlier in the day and run later into the night than HS1.
  • HS2 trains will be “much faster” than HS1.

Mr Sharps told the Committee that, for these four reasons, “in terms of noise implications, HS2 will be much more invasive”.

For his part, Mr Methold was able to add to this list when he appeared in front of the Committee: he pointed out that the lack of intermediate stations on HS2 would mean that the speed profiles achieved by trains would be closer to maximum speed for much longer meaning that, compared with HS1, HS2 was “a very different type of railway in that regard” (see footnote 3). Mr Methold was also able to make a significant contribution to the discussion by reinforcing this purely qualitative evidence with some enlightening quantitative information.

He showed the Committee exhibit A1571(35), explaining that it showed “the existing noise condition before railways appear”, termed the “baseline noise”, for both HS1 and HS2. He told the Committee that the level of this baseline noise was shown on the horizontal axis, and that “the other axis [shows] the percentage of the assessment locations exceeding that baseline [level]”. According to Mr Methold (see footnote 4):

“… if we look at the green dotted line, which is a baseline of 50dB, we can see that High Speed 2 baselines [the red curve], 59% of all the assessment locations are above 50dB. Whereas for High Speed 1, 93% of the High Speed 1 baselines [the blue curve] were above 50dB … this figure is showing that we have a very different situation in terms of route-wide existing noise levels just before the projects were planned.”

Faced with this fairly convincing demonstration that at least the first of the four bullet points set out above is valid, Robert Syms raised another of his cliché-like defences of HS2: “20% of the railway is tunnelled”. Mr Methold assured him that the fact was “obviously accounted for in [A1571(35)]” – I think that what he meant by this is that there are no HS2 airborne operational noise assessment locations above tunnels, so tunnels become automatically excluded from the analysis, which relates to surface sections of the route only (see footnote 5).

It surely comes as no surprise that, since HS2 will be running noisier, more frequent trains over more hours per day than HS1 and through previously quieter environments, generally, it can be expected that the former will have greater adverse effects upon residents living along the route than the latter. This was something that Mr Methold was able to quantify with his exhibit A1571(37). Mr Methold told the Committee that HS1 had relied on “noise change only” in order to identify its impacts and effects, and the table shown in A1571(37) provides a comparison between HS1 and HS2 on this same basis (see footnote 6).

Mr Methold’s table has three rows of data. He told the Committee that the first row related to “what was published in High Speed 1’s Environmental Statement” and the second row showed “how the scheme ended up being deployed … including all of the additional mitigation commitments that were offered through the Parliamentary process”. The third row, which relates to HS2, is “what is published in High Speed 2’s Environmental Statement”; Mr Methold noted that, unlike HS1, data is not yet available to enable him to “adjust [the HS2] numbers to take into account any further mitigation commitments that have been made during the Parliamentary process” (see footnote 7).

The table reveals a factor that may not be immediately obvious; the installation of a high speed railway can result in a decrease in the total noise impact on some receptors. Mr Methold explained that opportunities to do this for HS1 arose “because it was alongside transportation corridors” affording, for example, “opportunities to put noise barriers in locations that were [also] protecting the existing railways [and] existing motorways” (see footnote 8).

Mr Methold’s table provides figures of the total number of dwellings experiencing a noise change in each of five level bands, one for decrease and four different bands of increase. For the purposes of his analysis, a level change of between -3dB (decrease) and +3dB (increase) has been regarded as no change.

In the next posting in this series, I will report what Mr Methold had to say about the figures in his table.

(To be continued …)


  1. See paragraph 246 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015.
  2. See exhibit A1436(4) in the bundle of exhibits deposited with the Select Committee by HS2AA and paragraphs 15 and 16 in the transcript of the afternoon session of the HS2 Select Committee held on Monday 12thOctober 2015.
  3. See paragraph 250 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015.
  4. See paragraph 228 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015. Mr Methold explained to the Committee that noise levels used to construct the curves displayed on exhibit A1571(35) had been calculated as 24-hour Leq values, “because that was the metric that was used for High Speed 1”. He did not provide a conversion factor to the 16-hour LAeq used for HS2, but this information is not really required in order to appreciate the significance of the two curves.
  5. See paragraphs 243 and 244 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015.
  6. See paragraph 252 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015. Unlike HS2, the noise policy for HS1 set no minimum threshold level below which adverse impacts are ignored.
  7. See paragraph 253 of the transcript of the morning session of the HS2 Select Committee held on Wednesday 4thNovember 2015. The main mitigation improvement achieved, which is likely to reduce the HS2 figures to some extent, is the extension of the Chiltern tunnel.
  8. See paragraph 259 of the transcript of the morning session of the HS2 Select Committee 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.

Exhibits A1571(35) and A1571(37) have 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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