Examination of Witnesses (Questions 3130
- 3139)
3130. Chairman: The Committee will be
undertaking a visit to the Tottenham Court Road site on Tuesday
14 February. Any Petitioner or Agent with an interest in the site
may attend. However, I would be grateful if Agents would liaise
with the Clerk in
advance of the visit to finalise their attendance.
3131. Today the Committee will continue to hear the
petition of the London Borough of Camden. Mr Taylor, do you want
to continue?
Mr Rupert Thornely-Taylor, Recalled
Examination by Mr Taylor
3132. Mr Taylor: Thank you, Sir. Further
to events of yesterday, we have produced a note about Predicted
Floating Slab Track Costs which hopefully has been handed to the
Committee. I am told this document is number P45.
3133. Chairman: For the stenographers,
it is listed as A39.[1]
3134. Mr Taylor: I am going to ask Mr
Rupert Thornely-Taylor to take the Committee through this document
that has been produced. Mr Thornely-Taylor, would you like to
explain the note and what it sets out for the Committee, please?
(Mr Thornely-Taylor) Yes. What this note does
is to take what we know about the likely requirement for floating
slab based on predictions which have been made, and what we currently
understand about building foundations and matters of that kind,
because that is probably the best way of getting a feel for the
proportional increase in cost which will result from Camden's
proposed undertaking for Crossrail's approach as set out in information
paper D10. This is fairly specific. It begins in section 1 with
the costs per kilometre, the cost of floating slab track breaking
down as the track slab itself as £933,000 per kilometre plus
indirect costs and contingency costs taking us up to just under
£1.5 million per kilometre. These are all 2002 prices. Then
it sets out what we know as likely locations for floating slab,
maybe a different quantity from the possible outturn when uncertainties
are taken into account but it provides the most helpful way of
comparing the consequences of two competing proposals. First of
all, there is explicit mention in the Environmental Statement
itself, as we heard yesterday, of a total of one and a half kilometres
in the locations set out there and also in the work tables. In
the Noise and Vibration Specialist Technical Report there is more
detailed reference to a need for special trackform, which I explained
yesterday we assumed to be floating track slab.[2]
That leads to a broad assumption of an additional 1.4 kilometres.
What is meant by Level 2 Single Building Calculations, in the
next section, is that we have done calculations for buildings
with known special features, principally deep basements or pile
foundations but in other cases buildings with qualifications for
the lower assessment criteria that are in D10 such as sound recording
studios, theatres, concert halls and matters of that kind. That
gives us another 1.8 kilometres. The Crossrail position, based
upon that approach, is a requirement for 4.711 kilometres of floating
slab. That is the benchmark. We then look at the additional cost
associated with the Camden proposal and reapplying the forecast
through route windows C1 to C8. An additional 26 buildings are
identified with the result of taking 35 as the trigger, five of
these are already within the total that I have given. That gives
us an additional 21 buildings requiring floating slab and a requirement
for an additional 4.2 kilometres, giving a cost estimate for the
provision of this additional floating slab of £6.3 million.
As I have mentioned none of this includes the likely discovery
of further cases requiring floating slab that have come to light
during the detailed design stage. The figures I gave yesterday
of 10.6 million for the slab and a total, including contingencies,
of 16.96—I think it was—are actually the costing based
on engineering judgment as to what is appropriate to be included
in the cost estimates, allowing for what will turn up in the future
that we do not know about yet. That would be subject to the same
proportional dressing up that we see here for the more specific
information about things that we know about now. I hope that is
helpful.
3135. I want to turn to address the social surveys
which were conducted in the early 1990s, Mr Thornely-Taylor. Those
are set out in the Counsel information pack that was produced
yesterday at least as an Executive Summary at tab C.[3]
Could you please explain to the Committee what you say the findings
of that survey are and why the Committee should have regard to
them?
(Mr Thornely-Taylor) Yes. I think
the most important thing to bear in mind is we all recognise the
survey was small but it is useful information to take into account.
It did produce two conclusions that you will find in tab C of
the pack on page eight. It says "...two strong general conclusions
emerged of a kind which probably would still obtain were a much
larger sample studied. These were firstly that of reported annoyance
due to noise, only a tiny proportion of the annoyance is explained
by measured noise level. Significant correlations between noise
annoyance and physical measurements are only obtained when both
noise and vibration are included as independent variables."
We saw yesterday an exhibit of Camden's which was one off from
a full interpretive report which made it look as if three people
were very annoyed in the band 36 to 39.9 but it was only part
of the information because it tried to look also at people very
annoyed by vibration. The pattern is very similar, there were
two rather than three in that category, but it is explained by
this strong conclusion from this small sample that "...with
no vibration ...", it says, reading again from paragraph
4.2 "... annoyance due to noise is very low, and that noise
annoyance, for the same noise level, increases with increase in
vibration.[4]
The correlation between noise annoyance and vibration alone is
not much lower than that between vibration annoyance and vibration
alone." Another thing we heard about yesterday that was slightly
misleading was when talking about the North Downs Tunnel Mr Methold
was saying the vibration was below the threshold and these were
people disturbed only by noise. Why I say it is slightly misleading
is that you could be below the threshold of the low probability
of adverse comment, which is a term from the British Standard,
when vibration is well and truly feel-able and the vibration we
are talking about in the context of this survey was below the
threshold of low probability for adverse comment. So we must not
misinterpret the evidence yesterday about the North Downs Tunnel
to suggest people were complaining about noise with no vibration,
it does not follow from that evidence. The final thing I think
I need to say about the social survey is, quite rightly, Mr Methold
highlighted the very low correlation on the particular chart he
showed.
3136. I think that was LBC 24.[5]
(Mr Thornely-Taylor) Drawing the
single conclusion from that, if there was a complete correlation
it would be one, drawing the single conclusion that only indicated
that the survey was inadequate in some way. Of course you can
have a superb statistical survey of the population covering thousands
of people and get a very low correlation if you are studying something
from which there is a poor correlation. If you, for example, to
take a slightly ridiculous example, were studying the relationship
between the length of people's hair and the noise levels they
heard, you would get a low correlation, not because the survey
was poor but because it does not have much effect on the thing
you are studying. While I fully accept and say several times that
this survey was disappointingly small, the fact that the correlation
was small can perfectly well be because the link between grumble
noise level and annoyance is not as strong as you might think.
We do need to keep that very much in mind when taking an overall
view of what is happening.
3137. If we look at your non technical summary,
paragraph 3.3 you have explained there that "The striking
conclusion of the survey is the only reasonable correlations are
between vibration and reported annoyance, and as far as annoyance
due to noise is concerned, the best correlation was with measured
vibration"?[6]
(Mr Thornely-Taylor) That is
true and it is supported by people's general experience which
is that when there is underground train noise and you do not feel
anything through the sense of touch, what you hear—and I
have often described it as such and people have said "Oh,
yes, that is exactly what we find"—from the passing
train is very similar to the noise of a lorry passing on the road
at the end of your own road, a distant lorry passing. It is quite
difficult to distinguish the two. If there is vibration it is
all different. You would have the sense of intrusion, you have
this problem, which was highlighted yesterday, that you cannot
shut the window to get rid of it, and when there is vibration
and noise from an underground railway it is much more of a problem
than where there is noise only. Some of the well-known locations
in London with current problems, like South Kensington, from time
to time, just north east of King's Cross, and from time to time
Victoria to Brixton, where there are bad problems that London
Underground have to keep continually responding to representations
from the public, there are nearly always quite severe vibration
problems as well. I have been in buildings where if there is a
chair up against the wall it buzzes against the wall because of
the vibration and things like that which will make any of us complain
because it is a quite different effect from distant passing lorries.
3138. Two last matters. The first of which is
paragraph 4.2 of the conclusions, which you have already referred
to this morning. In the first sentence of that you explain that
there were two strong general conclusions which emerged. You have
already explained what those were. You go on to say "...
which probably would still obtain were a much larger sample studied".
Can you just explain to the Committee why it is you believe that
two strong conclusions probably would still obtain if you had
a larger sample?
(Mr Thornely-Taylor) There
are several indicators of that. One of them is that if you take
the raw data, and not separate out the noise and vibration and
the noise only cases, the percentage of people highly annoyed
is very much in line with the broad percentages you get from the
much bigger surveys that I was talking about on day seven in my
presentation when I showed a chart relating to noise levels to
percentage of people highly annoyed. None of the results fall
outside expectations in any way. The second point is really just
a further aspect of the description I gave of what one finds in
the field where people are complaining. It fits with observed
experience that it is noise and vibration which cause complaints
rather than noise on its own. That statement that it will probably
still obtain were a much larger sample studied is based on a combination
of those facts and 40 years' experience.
3139. Let us move on and turn to another document
in the file at tab E, The Guidelines for Community Noise.
First of all, can you please explain the status of this document,
Mr Thornely-Taylor?
(Mr Thornely-Taylor) This
is the report of an expert group whose deliberations were facilitated
by the World Health Organisation. It is the report of the four
authors listed there: Berglund, Lindvall, Schwela and Goh. It
is published, as we see on the first page, ii, on behalf of the
World Health Organisation. It is not a formal publication of the
World Health Organisation. There is the disclaimer that "The
authors alone are responsible for the views expressed in the document".
Nevertheless it is a very useful vade mecum of information
about the effects of noise on people. A wide range of international
experts are quoted and it is often called the WHO guidelines,
under whose auspices the work was facilitated.
1 Committee Ref: A39, Additional Cost associated with
Camden Design Criterion, Crossrail, 9 February 2006. Back
2
Crossrail Ref: P44, Environmental Statement, Noise and Vibration
Specialist Technical Report. Back
3
Crossrail Ref: P44, Noise and Social Survey Non-technical Summary,
Mr Rupert Thornely-Taylor, p3 (CAMDLB-31904-009). Back
4
Crossrail Ref: P44, Noise and Social Survey Non-technical Summary,
Mr Rupert Thornely-Taylor, p5 (CAMDLB-31904-011). Back
5
Committee Ref: A37, Petition on Groundborne Noise (CAMDLB-31905-001
to 039). Back
6
Crossrail Ref: P44, Noise and Social Survey Non-technical Summary,
Mr Rupert Thornely-Taylor, p4 (CAMDLB-31904-010). Back
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