Examination of Witnesses (Questions 17580
- 17599)
17580. There is mention there of the need to
close for about a month. We have communicated that to the Petitioner.
Is there anything more on that?
(Mr Berryman) No, I do not
think so, unless the Committee have any questions on that.
17581. Let us turn, please, from that point
to the question of settlement. Again trying to take this fairly
quickly—just a series of points really: have we assessed
the combined impacts, in respect of settlement, of the Crossrail
tunnels and the sewer proposals?
(Mr Berryman) Yes, we have.
17582. Have we prepared a report in relation
to that?
(Mr Berryman) We have.
17583. The Petitioners have been provided with
a copy.
(Mr Berryman) That is correct.
17584. Does that also embrace an assessment
of the sewer shafts?
(Mr Berryman) Yes, it does,
although all the sewer shafts are quite remote from buildings.
17585. What are the principal protective measures
that we anticipate will be required in relation to this facility
of work.
(Mr Berryman) We do not
think there will be any protective measures at all required to
the sewer tunnel. The issue is more with the running tunnels,
which, as you are aware, are very shallow at this point. There
we are doing our usual assessment of the impacts on properties
and offering a settlement deed for all the people who are affected.
17586. Turning to the particular point of the
Petitioners' document, page 25, would you comment on the accuracy
of this image.[42]
(Mr Berryman) This is not to
scale, contrary to what was said. We have a drawing which is to
scale, substantially to scale.
17587. That is 001.[43]
(Mr Berryman) The diameter of
the tunnel is, of course, as it says here, internally six metres
and externally about 6.6 metres. The design of the tunnel lining
is something undertaken normally by the contractor, so the exact
thickness, whether 300 mm or 375 mm or whatever, we do not know
at this stage, but it is in that area. Page 001 is a section which
is to scale. It shows the house at the top and at the same scale
the tunnel underneath. I believe this was prepared for Mrs Wheeler,
one of the Petitioners we will be hearing from later. You can
see the relative scale of this is substantially different from
the other sketch.
17588. There was mention, I think, this morning
of a figure of 1.7%. Can you explain the significance of that?
(Mr Berryman) If you recall
all the way back to the beginning when Professor Mair gave a talk
on certain petitions generally, the 1.7% refers to the ground
loss or relaxation which would occur when the tunnel is driven,
and it is a reference to the percentage of the volume of the tunnel
which will be lost. If you remember, that is spread over a very
wide zone of settlement. I think Professor Mair may have given
quite a long talk about that. The 1.7% does not relate to the
compression of the ground between the top of the tunnel and the
ground surface; it relates to the volume which is lost to tunnel.
The 1.7% we have used, we know from other tunnelling projects,
is very conservative and normally on the Channel tunnel Rail Link
they have been achieving about 1.5% as a general rule. So we know
they make very, very conservative assumptions. It is also worth
mentioning the difference between settlement, which is what we
expect to happen over a tunnel in any event, to a greater or lesser
degree, and the kind of catastrophic collapse which the Petitioner
mentioned this morning. Obviously, there are ways of avoiding
that by effective management of the proposals, but it is not something
that we would expect to happen.
Mr Binley: Just to get 11 metres
in my mind, would this ceiling be 11 metres?
(Mr Berryman) Eleven metres
would be six people standing on top of each other. It may be 9
metres, I do not know.
17589. Probably a bit more.
(Mr Berryman) It is very
hard to estimate in here.
17590. I am just trying to get a feel. Thank
you.
(Mr Berryman) That, of course,
is to the top of the tunnel.
17591. Chairman: Just on the ground in
the tunnel, what kind of ground is in this particular area? It
is not the same—or is it the same—as we discussed
in the City: London clay and so forth?
(Mr Berryman) I think at
this point we are out of the London clay. I think it is reasonable
ground. I can get an answer to that very quickly.
17592. Mr Mould: I am told it is mainly
London clay with gravel overlaying.
17593. Chairman: Could you give us that
note anyway?
(Mr Berryman) I will give
you a note, sir.
17594. Mr Mould: Can we move away from
settlement and just touch on another matter, which was the question
of night-time working. I have put up an extract from the additional
provisions which sets out, in 5.3.5, the reference to 24-hour
working.[44]
Can you summarise for the Committee the position in relation to
night-time working in relation to this part of the project?
(Mr Berryman) The significant
impacts of night-time working are at the existing McDonald's site
near the junction of the A12 and the A11, down near the flyover
which the Petitioner pointed out earlier. That would be a 24-hour-a-day
site. The other sites will generally be daytime only, except for
specific items of work. If you could put slide 38 up, just to
illustrate the point. The shaft at Grove Hall Park will, generally
speaking, be a daytime only site. There might be a very small
amount, a couple of nights, of night work when we join on to the
new tunnel. This site here will be a 24-hour-a-day site, although,
as you will appreciate, this is a very noisy location anyway with
the Blackwall Tunnel Road. This site will be generally a daytime
site except for the restriction of a retaining wall here, which
may have to be done at night. When I say "may have to be
done at night" it may have to be done, and if it is done
it is done at night. There is a possibility we may be able to
get away without doing it at all. Then there will be some night-time
working when we withdraw the tunnel boring machines from here.
At these two sites there will be night work because what we are
doing here is filling the disused sewer with foam concrete, and
that is just a question of bringing a truck mixer in and literally
pouring concrete down a manhole. Of course, this road will be
kept open; it is very busy. The noise of that work will be not
detectable above the background levels there, and similarly for
this site here. Again, for very short durations, I think from
memory about six nights and this one is about four nights.
17595. Finally, sir, if I can make this point,
the question of the potential impact of a lorry route past the
local school was mentioned this morning. I am bound to say that
was news to me. I can say that if it is right that lorries would
be routed past a local school—we will check that—then
I am told that the arrangements that we have already told the
Committee we will commit to in relation to schools in Whitechapel
and going in and coming out times will be applied in relation
to that school as well.
(Mr Berryman) That is correct.
17596. Chairman: All lorries used will
be sheeted over?
(Mr Berryman) Yes, throughout
the project that will be the case.
17597. On the top sites, which is concrete mixing,
is the mixing on site?
(Mr Berryman) No, that will
come from a ready-mix concrete plant and, as I say, just literally
poured down the manhole. It is not quite as simple as that, but
that is the general gist of it.
17598. The final thing is in relation to the
request for similar arrangements as Whitechapel on the one-stop
kind of shop for all inquiries, and to liaise.
(Mr Berryman) In principle
the answer is yes. We will be producing a community relations
strategy in due course.
17599. When will that be available?
(Mr Berryman) It is available
in draft already. It is going round for discussion with local
authorities. It is not going to be ready in the next few weeks
but it should be ready by the end of the year.
42 Committee Ref: A193, Fairfield Conservation Area
Residents Association, Baldock Street (TOWHLB-29105-025). Back
43
Crossrail Ref: P126, Tunnel Gradient and Long Section-Mrs Barbara
Wheeler, 1 Baldock Street, Bow E3 2TP (TOWHLB-31204-001). Back
44
Amendment of Provisions Environmental Statement-May 2006, Chapter
5, Route Windows C13 and C13A: Pudding Mill Lane Portal and Abbey
Mills Duration of the Works, billdocuments.crossrail.co.uk (SCN-20061018-002). Back
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