Examination of Witnesses (Questions 3340
- 3359)
3340. In relation to the guidelines for community
noise document, what is the scientific basis for the guideline
in table 4.1?
(Mr Thornely-Taylor) It is very soundly based
work using what are called meta-analysis of a large number of
social surveys bringing them altogether and collapsing the data
into one conclusion. It is the work that is referred to in the
WHO document that underlies the chart which I showed in my presentation
to link noise levels of percentage annoyed. Those data are as
statistically robust as any information which exists of that nature.
3341. You were also asked about that community
noise document, where does it deal with groundborne noise, and
you have confirmed that it does not explicitly deal with groundborne
noise. Can you explain why the document is relevant to the Committee's
consideration of the issues that are before it in this matter?
(Mr Thornely-Taylor) I cannot be certain it
does not make passing reference to groundborne noise, it may do,
but not in the sections we have. To the extent that I was likening
the noise of a passenger Crossrail train without feeling the vibrations
to the noise of a passenger lorry passing at the end of the road,
its transportation noise inside buildings is just like any other,
subject to what was put to me by Mr Clarkson, which I agree with,
both noise coming up through the pillow and things like that.
3342. You were cross-examined about the information
that was provided in relation to the Victoria Line of the Social
Survey, various matters of that kind, and the point was put to
you that what we are looking for is serious technical data. Do
you recall that?
(Mr Thornely-Taylor) I do, yes.
3343. What serious technical data have you seen
that demonstrates the adoption of a design criterion of 35 would
result in material improvement to the noise climate in people's
homes as opposed to the adoption 40?
(Mr Thornely-Taylor) I agree with Mr Methold
and would likewise say none?
3344. Thank you? The point was put to you regarding
the criterion used in the Jubilee Line extension. Do you remember
you were referred to the desirable level of 45. Can you confirm
to me what the design criterion was that was adopted with the
Jubilee Line extension?
(Mr Thornely-Taylor) Forty, exactly as in the
terms of Crossrail.
3345. Are you aware of any complaints or any
records of annoyance being made arising from the Jubilee Line
extension in operation?
(Mr Thornely-Taylor) No, I am not.
3346. Mrs James raised a point about ear
plugs and tablets being provided to people on American cruises.
I have never been on an American cruise ship in my life, unfortunately.
I want to understand what you said in response, that it was a
good illustration of low frequency noise. I want to contrast the
position of somebody on one of those cruise ships with the position
of somebody in a residential property, above one of the proposed
Crossrail tunnels. What are the differences that would be experienced
between those two cases?
(Mr Thornely-Taylor) Mrs James was referring
to low frequency noise in the context of some of the comments
made in the WHO document. It is a much lower frequency than what
we are talking about caused by the passenger underground trains,
though I think the Committee will find when they do hear it, it
is a low rumble. It is not low in the sense of low frequency as
is known. There is a professional society devoted to low frequency
noise and it addresses these exceptionally drumming, pulsating
noises, including that well known elusive phenomenon which occasionally
gets into the papers in parts of the country. These are all much
lower frequencies and have a different effect from anything you
would hear from a passing underground train. They merit a study
and measures to try and understand them and deal with them. No
doubt on a cruise ship, ear plugs and tablets are used, but that
is quite a different matter from what we are going to get from
underground trains.
3347. That was the low frequency aspect of the
issue raised by Mrs James. She also mentioned vibration. Can you
contrast the position in terms of vibration between Crossrail
and the American cruise ship?
(Mr Thornely-Taylor) Ships have the vibration
problem become of the relatively non-rigid nature of a steel hard
ship. There are probably five levels of magnitude different between
the vibration on a ship and the vibration of an underground railway.
There will be nothing feelable through the tactile sense above
the Crossrail Tunnel at any location.
3348. You were also taken to the fact that there
was reference made to the London Mayor's Ambient Noise Strategy
and also reference to the Local Authority adopted policies we
can see the extract from the Ambient Noise Strategy at LBC12.
The policy set there refers being required to: "Minimise
any adverse impact...". If 40 is adopted as a design criterion,
what is your view as to whether there would be adverse impacts
or otherwise?
(Mr Thornely-Taylor) I think the Mayor's sentence
there would be well achieved by the policy which includes the
40 figure using the best available cost-effective technologies,
and we will be minimising adverse effect of noise vibration below
40. It would be hard to describe it as an adverse impact. In at
least several of the schemes we have looked at the threshold of
significant effect is 40. It would be hard to use the word adverse
impact below 40. As we have seen from the predictions, we do achieve
levels much less than 40 as a result of this approach.
3349. Thank you very much indeed, Mr Thornely-Taylor.
3350. Chairman: Mr Clarkson, you asked
for permission to recall your witness, I wonder if you still want
to do that? Bear in mind this is only to question this particular
document?
3351. Mr Clarkson: I think I am content
in the sense that I am extremely discontent by the fact that you
have only had this material at 10 o'clock on day 11. I can submit
around that conclusion at the end of 6.3 million additional FST
in context, whether it is 8 million or 4 million I think the Committee
has got the point.
3352. Chairman: Thank you very much.
Mr Taylor, do you want to make your final statement.
3353. Mr Taylor: I make this statement
in the context of the undertakings that have been sought by the
London Borough of Camden, which are set out in LBC 37 and 38.
Starting firstly with the first undertaking. That seeks to apply
the best practical means to construction tunnelling and the temporary
construction railway. The draft Construction Code already commits
to a nominated undertaker to employ the best practical means to
mitigate noise and vibration in relation to all construction.
You have seen that from paragraph 5.1.1 of the Draft Code in information
paper D1.
3354. Further, information paper D10 commits
the nominated undertaker to meeting the 40 dB(A) LAmax threshold
in relation to the construction railway. These commitments embrace
the matters sought about London Borough of Camden in its first
draft undertaking. So far as the consultation issues that were
raised in undertaking 2 and 3 apply, there is already extensive
provision for consultation with local authorities in commitments
given. This includes the creation of the Environmental Health
subgroup of the planning forum.
3355. Local authorities and local residents
will be provided with the relevant information and will be consulted
on matters pertinent to groundborne noise as the project progresses.
The references there are to information paper F3, paragraph 2.5(ii)
and (iii), information paper F4 and the information paper D10,
paragraph 2.10. The main part of the second undertaking 2, that
is to say, alternative accommodation during the passage of the
TBM. Mr Thornely-Taylor explained that there is no reliable method
to assess the likely impact of the passage of the TBM. As a result,
the only reasonable basis, he said, on which to approach the undertaking
sought by the London Borough of Camden is to assume that it will
relate to every residential property above the tunnelling route.
3356. The undertaking sought would therefore
give rise to a substantial and unquantifiable additional cost
to the project. A scheme for the provision of alternative accommodation
has not been provided for in relation to the tunnelling of any
railway in the UK before, as Mr Methold confirmed.
3357. Undertaking 5: Maintenance regime. It
is common ground that there needs to be an appropriate regime
in place to ensure that track and equipment is appropriately maintained
so as to control groundborne noise.
3358. Mr Rupert Thornely-Taylor has explained
what that entails in his evidence. The promoter has committed
to that principle in information paper D10, paragraph 2.10, and
will continue discussions with the London Borough of Camden with
a view to establishing robust and appropriate assessment criteria.
3359. Undertaking 4: This is the undertaking
which relates firstly to the inclusion of best practicable means
and, secondly, the adoption of 35 dB(A) LAmax criterion to design
the railway. I will start first by addressing matters relating
to the best practicable means part of the undertaking. Mr Methold
explained that in his view 35 dB(A) LAmax represented an acceptable
level of noise within residential properties. He accepted in cross-examination
the reference to employing best practicable means to the design
of the railway was intended to embrace the position where 35 could
not be attained. That is not what the words of the draft undertaking
4 achieve.
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