Examination of Witnesses (Questions 5640
- 5659)
5640. MR TAYLOR: Thank you very much.
I think the last matter I want to ask you about is this issue
of audibility. Given the sort of forecast that we are looking
at in respect of Spitalfields area, Mr Thornely-Taylor, what can
you say to the Committee about the extent to which it is likely
that the passage of trains will be audible within residential
properties?
(Mr Thornely-Taylor) I wonder if I could,
first of all, say, as I think your Lordship knows, I sit in a
similar position in regard to new airports, new highways, new
ports, new infrastructure projects of all kinds and never is it
the objective to achieve audibility. I know of no airport or motorway
or any other major infrastructure project where the requirement
is that nobody hears it. That said, as I have been explaining,
unusually an underground railway is capable of achieving very
low noise levels, much lower than you would expect if we were
planning an airport nearby, for example. Having said that, it
would be wrong of me to suggest the trains would not be audible.
We know from our site visit that you can hear trains passing at
the levels we are talking about. They are, albeit quiet and in
a building which is not far from a road—it is quite difficult
to distinguish the noise of a passing underground train designed
to the standards which I have explained from any other event,
a vehicle passing the end of the road, street, all the other things
which are in the normal environment. It would be quite wrong of
me to say Crossrail would be inaudible in general, there are many
places where it will be but it would be wrong to say that of Spitalfields.
It will not differ from the ambient noise environment which is
quite normal for central London residential areas.
5641. CHAIRMAN: We did not hear any trains
of the Crossrail standard when we were in the hotel.
(Mr Thornely-Taylor)
We did not, you are quite right, my Lord. We were listening to
an old-style railway because that was all we could come up with.
The Jubilee Line Extension, which is constructed to modern standards,
does not produce high enough noise levels for there to be anywhere
I could take your Lordships and your Ladyship to listen to. The
noise levels are all too low for there to be anything to go and
experience.
5642. MR TAYLOR: Thank you very much
indeed, Mr Thornely-Taylor, those are all the questions I have.
5643. LORD BROOKE OF ALVERTHORPE: Did
we not listen with broadcasting silence?
(Mr Thornely-Taylor) We did indeed, my
Lord. I am not sure how successful we were, there were some 20-odd
people in the room, I did not count them. It was quite difficult
to get down to the real base noise level, but it was a remarkably
quiet room. I was very pleased to have discovered a place like
that which was so quiet in which we could listen to those noises.
5644. LORD JAMES OF BLACKHEATH: Mr Thornely-Taylor,
I did count them. The maximum was 16 in the room at any time period
during the test.
(Mr Thornely-Taylor) That is very helpful,
my Lord. I am grateful for that.
5645. CHAIRMAN: Ms Jones?
5646. MS JONES: Thank you. Mr Thornely-Taylor,
you said on the question of audibility, I am not sure here whether
you are talking about the predicted noise levels here or at 40
dB that would not differ from the ambient noise levels if you
have a road outside. Could you explain that? Would that be if
the noise of the trains is 40 dBL and your noise level inside
the property is less, let us assume it is 30, would you hear the
trains on top of the other external noise?
(Mr Thornely-Taylor) There are two parts
to my answer, my Lord. The comment I just made was specifically
about Spitalfields. The low levels of noise predicted for Crossrail
will not be much different from ambient noise events due to traffic
on local roads. The second part of my answer relates to any case
where we do come right up to 40, that is not predicted for Spitalfields,
but if that were the case, the passage of the train would be as
audible as we discovered in the site visit.
5647. Mr Thornely-Taylor, on the site visit
I understand that was simply one train?
(Mr Thornely-Taylor) No, my Lord.
5648. MS JONES: That was a number of
trains. Thank you.
(Mr Thornely-Taylor) As your Lordships
know, we were there for some time and we heard a range of trains,
fortunately covering a nice wide range of noise levels. I did
not time our presence on site. I do not know whether my Lord,
Lord James, has—
5649. LORD JAMES OF BLACKHEATH: Twenty-two
minutes and nine examples.
(Mr Thornely-Taylor)
Thank you, my Lord.
5650. MS JONES: Thank you for explaining
that. You said that at the predicted noise levels for Crossrail
here that with the local roads you would not expect the trains
to be heard but of course the local roads within this tiny little
area are extremely quiet, they are very narrow and on the pure
residential roads, for example Brooke Street and Princelet Street,
there is not a huge amount of traffic there. Would that change
your evaluation?
(Mr Thornely-Taylor) No, my Lord. My reply
was given knowing the characteristics of Spitalfields, which I
have known on and off for 45 years or so, so I am very aware of
the nature of the narrow streets and the comparative lack of traffic
in local streets.
5651. Could you comment, Mr Thornely-Taylor,
on the Arup report which said that at levels even below the background
noise levels, the trains would still be audible?
(Mr Thornely-Taylor) Yes, what they are
explaining—their comments are in respect of Christ Church,
Spitalfields—that inside the church general traffic noise
levels are in the low 30s, I think they mentioned a figure of
32, and there is no reason to doubt that. What they are saying
is if a Crossrail train should pass, there will be a slight difference
in the shape of the sound spectrum in the hall and given that
this is regarded as an auditorium and people will be particularly
critical of the quality of the sound that is heard it may be possible
to distinguish the different spectral characteristic of a passing
underground train from the characteristics of traffic. That is
the point they are making.
5652. Thank you. Could I ask you with your modelling
whether the sound modelling has been accepted by other independent
sound engineers?
(Mr Thornely-Taylor) Yes, in fact one
of the world's leading consultancies in Scandinavia subcontracts
its modelling of this kind of work to my practice. We have done
a very large amount of similar modelling on systems throughout
the world, not only Scandinavia but the Far East and Australia,
other overseas systems. It is, in fact, one of the very few—I
hesitate to say the only—methods of doing a full three-dimensional
modelling of the movement of a train in the time domain and for
that reason it is widely used on many systems and accepted by
Arup, who, as we all know, are one of the leading consultancies
in this field.
5653. Was that also accepted by the Soho sound
studios in relation to the issues they have got in their premises?
(Mr Thornely-Taylor) We will, I believe,
my Lord, be hearing a Petition from the Soho studio who are very
concerned about the consequences of uncertainty and I think I
am right in saying consequently have a compensation point about
what if it does not turn out as predicted. It will be seen, I
expect, when their evidence is presented that they look very closely
at this issue of uncertainty and, therefore, I have been at pains
to explain both the first time I appeared before your Lordships
and Ladyship the issues involved and how they are addressed and
what the risk is that a prediction might turn out to be inaccurate.
5654. MS JONES: Could you explain, if
there is background noise of 40 and the trains are at 40 is there
any incremental increase in the noise? I am thinking, for example,
if you have someone singing outside your house, if you have two
people singing it is generally louder.
(Mr Thornely-Taylor) If two events occurred
at the same time and each was individually 40, the resulting measurement
would be 43.
5655. CHAIRMAN: Forty-three?
(Mr Thornely-Taylor) Forty-three, yes,
my Lord.
5656. MS JONES: Thank you. Forgive me
if I am leading the witness, I am not used to doing this. Can
I take it then that at 40 decibels, ignoring the fact for the
moment the noise contours you are expecting it to be less at Spitalfields
at 40 dB, if that is what the track is designed to take and the
ambient levels outside are less, you will hear the trains?
(Mr Thornely-Taylor)
There are several "ifs" there, but if they are all true
the answer is yes.
5657. If the track was designed or there were
particular structural embellishments made, which I think is called
"floating-slab track", so as to ensure that was 25 dB,
would you hear the trains?
(Mr Thornely-Taylor) Most people would
not hear them.
5658. Thank you. Could I ask one more question
on the terms of the Information Paper which refers to the nominated
subcontractor. Could we get that up again, I think that is D10.[7]
Paragraph 2.7: "The nominated undertaker will endeavour to
ensure the noise levels are achieved. The nominated undertaker
will be required to design a permanent track support system",
and this is policy, I believe, but of course we, the petitioners,
have absolutely no contractual nexus with the nominated subcontractor
in this instance so if the nominated undertaker does not do that,
there is nothing we can do about it. So that is why --- Sorry,
I am supposed to be asking questions. Mr Thornely-Taylor, would
you agree that we have no contractual recourse against the nominated
undertaker?
(Mr Thornely-Taylor) My Lord, it is nothing
like as stark as has been suggested. As I think your Lordships
and Ladyship are aware, the generic topic of noise from movement
of underground trains is being taken by the London Borough of
Camden and we have been working very hard with them to agree the
terms of this Information Paper and, in particular, the process
through which information will be provided to the local authorities
and there will be many opportunities for local authorities to
see how the design is progressing and what the likely outturn
is. There is no possibility that there will be a sudden surprise
and a nominated undertaker will suddenly produce some track form
which was in any way inadequate or inappropriate to this Information
Paper. The important feature of the whole of the description that
I have given of the approach to procuring the underground railway
is it is a procurement system which will achieve a successful
outcome. It is not just about getting the right numbers in specific
local cases. It is all designed to make quite sure that the whole
approach is a modern approach that gives us a state of the art,
most cost-effective form of rail support that will produce the
lowest reasonable noise levels so I do not think individual petitioners
need have fear unless they completely distrust local authorities
and their abilities to make an input to the consultation process
that I have described.
5659. Would you agree that if they were required
to design or put in track support systems to ensure that the levels
were not above 25, then that would mitigate, certainly minimise,
the risk of things going wrong and it being louder in practice
and minimise problems in future with the track maintenance?
(Mr Thornely-Taylor) My Lords, that alone
will not achieve that objective. It is regrettably possible to
install floating track slab that does not work, is badly designed
and gives rise to all sorts of engineering consequences. It is
not sufficient just to say, "Thou shalt" put in a form
of track which is described by three words, you need to have an
overall procurement approach, a design, management and monitoring
approach to the process of achieving a state of the art track
form. You do not get what you think you are going to get simply
by inserting some words in place of others. It is the overall
process that is important rather than specific descriptions which
(a) may not refer to what you think they refer and (b) just by
a simple description do not ensure that high standards of competent
design are achieved and the outcome is what you expect it to be.
7 Crossrail Information Paper D10-Groundborne Noise
and Vibration, http://billdocuments.crossrail.co.uk
(LINEWD-IPD10-004) Back
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