Examination of Witnesses (Questions 5600
- 5619)
5600. When we are talking about noise I understand
that the levels which the Promoter is designing the track to for
residential properties is 40 dBL. I understand your Lordships
went on a site visit, or at least some of you did, to hear the
noise levels. As far as I am aware we have never been invited
to go on one of those trips, and it would have been extremely
useful because then we would actually know what a train sounds
like at 40 dBL.
5601. CHAIRMAN: I do not think you would
because there was only one. It is a central line and it runs on
jointed tracks and that is what we heard. Most of them were well
below 40.
5602. MS JONES: I think in the transcript
I recall that that was recorded at 47 dBL. That was the one in
Spital Square according to the transcript.
5603. CHAIRMAN: I do not think it was
47.
5604. LORD BROOKE OF ALVERTHORPE: I think
41 was the highest in our site visit.
5605. MS JONES: I will check the transcript
because I am almost positive it said 47, and the comment was made
that it was "very noisy". However, if we think about
one train of course that is just one isolated train; here with
the Crossrail trains, and forgive me if I am wrong, I think it
is something like 24 an hour. It is a substantial number, so it
is not a one-off event; it is a continual noise from the trains.
What the Petitioners would expect is that the noise levels which
they currently experience in their properties by means of the
background level are not exceeded by the trains, to the extent
that actually you would hear the trains running above anything
else which is the background noise. That of course depends very
much on what the background noise is.
5606. I think if we look at the papers—I
did send them electronically so perhaps we could have them up
on screen—it would be 46.[2]
This is the only section from Arup which is I think attached to
a letter from a Promoter, because in response to the Committee
in the other place I think it was Christ Church Festival, which
does various recordings in Christ Church, which asked if they
could be assured as to the noise levels in the church. The church
is just on the edge of the settlement contours, quite near the
running tunnels; not on them but fairly near.
5607. CHAIRMAN: I think we know where
it is.
5608. MS JONES: If we look at the section
that deals with the background noise levels, which is the fourth
paragraph, Arup's are saying here that the "maximum sound
level during the passage of a train [and this is for Christ Church
which is further away from the running tunnels] would be 27 ...
to 29 dB(A) [or dBL]. Under typical conditions inside the church,
namely when road traffic is typical, the measured background noise
levels ... were 34 db(A)". It seems to me what Arup are saying
there is that at Christ Church the background levels are 34.
5609. Christ Church fronts onto Commercial Street;
that is a very busy road; it is one of the main arteries through
London and there is a lot of heavy traffic and a lot of heavy
lorries. We can ask Mr Thornely-Taylor later but generally speaking
I would have thought for the actual properties within the Spitalfields
area the background noise levels on a normal day, not taking into
account any isolated incidents, are probably less than that, because
they are protected by a number of very large buildings from Commercial
Street which would operate as a noise barrier. The streets they
are on are fairly quiet. We probably get one car every ten or
15 minutes or so. I think we could probably assume that the background
noise levels are lower than they are in Christ Church.
5610. CHAIRMAN: You can ask Mr Thornely-Taylor
about this.
5611. MS JONES: Yes. Interestingly, Arup
also say here that even with the predicted noise levels of 27
to 29, they would still be audible. Even with a background level
of 34 dB, the train levels would still be audible. They do say
it is unlikely to be disturbing but they say it would still be
audible. I think we can take it that at 40 dB the trains will
certainly be audible.
5612. The Promoter I think is relying on the
general background noise levels to say, "Because of the general
background you won't be disturbed; you won't hear it". I
find that quite difficult to understand. We can ask Mr Thornely-Taylor,
but I would say if your background noise levels are in the 30s,
at 40 dB with the trains you will be able to hear them. I would
say that that would be disturbing, because it is certainly over
the levels people are experiencing at the moment.
5613. I think also the 40 dB for residential
properties has probably been around for some time and, of course,
life has changed considerably over the past ten years. There are
a lot more single people living in properties; there are a lot
more people working at home; so the general background noise levels
of properties are probably likely to be much lower anyway. You
are not going to have a home where the washing machine is going
24 hours a day in most of these properties. My basic point is
that the background noise levels will probably be in the region
of 30; and the noise of the trains, if the tracks are designed
at 40, that is going to be disturbing.
5614. If I could emphasise the point, it is
not just one train going every ten or 20 minutes. I think Mr Thornely-Taylor
referred to the fact if you were standing in a room any noise
would take you into a higher level. If someone coughed you would
be into a higher level; but of course those are very isolated
incidents. If you have got trains running 24 an hour that is a
very, very constant loud noise at 40 decibels.
5615. It is clear from the Information Paper
and also from what Mr Thornely-Taylor has been saying that you
can design a track to a lower noise level. It can be designed
to 25, because of course in some cases that is exactly what the
Promoter is doing but it is simply a matter of cost. We would
say that putting that sort of track support through Spitalfields,
and I am only talking here about Spitalfields, the cost of that
must be insignificant to this project. According to the Arup letter
I think we are also seeing that some of that track may have to
be put in anyway to mitigate the noise at Christ Church, because
that is not just used as a church for worship, it is used as an
auditorium for recording purposes as well.
5616. My submission on the noise is that the
track should be designed at 25 decibels to go through Spitalfields
and, in particular, that would almost mitigate the risk that,
if it is designed to 40 decibels then, as we know things can always
go wrong. I suspect there is very little you can do about something
if you have designed it, say, to 40 and it is not quite right
and it is higher. Why not design it to a lower level and then
you have got that comfort zone?
5617. It also deals with the point which Mr
Thornely-Taylor raised that the rolling stock has to be maintained
properly in order to keep those levels. Again, it would deal with
that risk considerably if the track was designed to a lower level.
5618. As I said, in my opinion the cost of doing
it through Spitalfields would be insignificant to this project.
It probably has got to be done to accommodate Christ Church and
the recording facility anyway. If I can go back to the individual
petitioners and the members of the various societies and say "The
track will be designed so you will not hear the trains",
then I think that would be what they would expect from the Promoter.
That is all I have to say on the noise issue.
5619. CHAIRMAN: You can say more about
this at the end after you have been able to explore it with Mr
Thornely-Taylor.
2 Committee Ref: A27, Comments on completion of Groundborne
Noise modelling at Christ Church Spialfields, Arup Acoustics,
12 July 2007 (TOWHLB-18_05-046) Back
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