Examination of Witnesses (Questions 3220
- 3239)
3220. But the noise standard is the same, is
it not?
(Mr Thornely-Taylor) For a different purpose.
3221. Look next, please, at LBC9 and 10. Nine,
first of all, the American Public Transit Association design goals.
I think you invoked these as advisory, did you not?
(Mr Thornely-Taylor) LBC9 in my pack is the
American Public Transit Association.
3222. Yes.
(Mr Thornely-Taylor) I do not think I have
ever invoked them. I have never really understood them. They have
been in front of me in each of the tribunals where we have had
this argument and ended up with 40 as a policy.
3223. Did you have in front of you the latest
material that is the FTA document, which is LBC9?
(Mr Thornely-Taylor) We had that for the Channel
Tunnel Rail Link.
3224. Yes.
(Mr Thornely-Taylor) In my pack FTA is not
LBC 9.
3225. LBC 10, the next one.
(Mr Thornely-Taylor) Yes.
3226. Can we agree that in the United States
groundborne noise impact assessment criteria are set at 35 for
frequent events?
(Mr Thornely-Taylor) As they are here in Crossrail,
our assessment criteria start at 35 as we were looking at a moment
ago. I am not sure that this has been reproduced accurately because
I do not think the assessment is in the original document, but
I will let that pass.
3227. Good.
(Mr Thornely-Taylor) And compare those levels
with the assessment criteria of both the CTRL and Crossrail where
35 is the lowest number in the matrix for considering groundborne
noise.
3228. Is it your case that the Committee should
impose a maximum dB(A) of 35, in which case I will sit down?
(Mr Thornely-Taylor) It is my case that the
Committee should ask for an approach to the procurement of the
railway that will achieve the very good outcome that we achieved
with the Jubilee Line Extension bearing in mind everything that
takes place between imposing a number and writing the words to
go with it and writing contract documents and administering the
contract and checking the performance of the contractor. I firmly
believe, and it is my own decision—I could have taken a
different view but I do not have to pay for the railway—the
way we did it works best. I firmly believe that the Camden approach
is actually damaging in introducing concepts like Best Practicable
Means. We do not need Best Practicable Means, we can do these
numbers. We need to write them in in the precise way that will
achieve them in the contract in ways that do not give the contractor
a let-out but in ways which bring about a system that for the
greater part of it is much better than 40, which is what you get
from adopting this as an approach. I firmly believe as a very
experienced practitioner in this field that we are doing it right.
If it ain't broke, don't fix it.
3229. From what you have just said, are you
advising the Committee that if they are persuaded as to the Camden
35 dB(A) plus Best Practicable Means to say take out Best Practicable
Means, is that right?
(Mr Thornely-Taylor) Yes. If the Committee
were attracted to the number 35, I would recommend they just changed
40 to 35, but the consequences of that would be very large because
I have already talked about the uncertainties and the unforeseen
problems that arise when the detailed design comes along. I do
not think it would be practicable and therefore we would be unable
to be sure of achieving the good outcome that I have talked about,
in those circumstances, without taking a wholly different approach
and looking at a floating track railway rather than a resilient
base railway. I do not think we should put in best practicable
means.
3230. We will note that and I am sure your clients
will appreciate it. LBC17 next, please. I want you to help the
Committee with the comparators. Is there a difference between
35 dB and 40 dB?
(Mr Thornely-Taylor) There clearly is a difference.
I am not quite sure of the question.
3231. The answer is yes?
(Mr Thornely-Taylor) There is a five unit difference.
3232. A difference so important that some shall
have the benefit of a ceiling of 35 and some shall not?
(Mr Thornely-Taylor) It is the usual way of
classing different noise impacts into bands, to carve them up
into 5 dB steps.
3233. There is a difference between 40 and 35
that is so substantial that it is worth doing for a church and
not for an office or a residence?
(Mr Thornely-Taylor) I do not use your semantics.
I simply say that five is the customary way of dividing up a range
of targets into a convenient set of classes. That is not so substantial.
Mr Methold himself said it was a noticeable difference. I referred
to Mr Methold's evidence and I agree with him.
3234. You are not going to trivialise it, are
you, because otherwise you are deceiving us by saying that a church
should have 35. There must be a difference.
(Mr Thornely-Taylor) There is a difference.
I hope the Committee can hear it for themselves. They will not
find it enormous but they will notice it and see why we use five
as a classification system. There was a moment when we were slightly
alarmed and Mr Methold was saying there was a three fold change
in energy. I was at pains to point out on day seven that the ear
does not respond to energy in that way. It is a significant change
but not as big as you would think from that comment.
3235. On day eight I think you told us that
a 10 dB(A) increase is a doubling?
(Mr Thornely-Taylor) I did.
3236. And a five is a 50 per cent increase.
Correct?
(Mr Thornely-Taylor) I did not say that. It
is not. If you take the square root of two, you get 1.4.
3237. What is it then?
(Mr Thornely-Taylor) 40 per cent.
3238. For the Committee, what they are talking
about is a church being treated differently to the extent that
it will have a 40 per cent reduction in groundborne noise compared
to a bedroom.
(Mr Thornely-Taylor) Yes.
3239. Why?
(Mr Thornely-Taylor) Because what you are concerned
about in bedrooms is primarily the effect of noise on sleep. What
we are concerned about in churches and some of the other categories
there, which also have levels lower than 40, is the effect of
sound on acoustical characteristics of the space, because people
are listening to music where sound would be intrusive in a qualitative,
artistic sense and the artistic qualities of a building are regarded
as a valuable resource; whereas the effect of noise is studied
from a completely different standpoint. It is studying what effect
noise has on a population of people, having already had a tour
round it in the document by the World Health Organisation authors,
and the conclusions they make are now well known to the Committee.
| 
