Examination of Witnesses (Questions 4120
- 4139)
4120. What we characterise as an individual
assessment of buildings of that character, yes?
(Professor Mair) Yes, that is correct.
4121. My Lord, may I interject here. A question
arose yesterday as to when these Phase 3 Stage 1 reports in relation
to listed buildings in Spitalfields had been sent to Petitioners.
I have asked for instructions on that and the information which
we have is that Phase 3 Stage 1 reports in relation to listed
buildings in the Spitalfields area were sent to Mr Carpenter in
his capacity as the Chair of the Woodseer and Hanbury Street Residents
Association on 3 November 2004. Professor Mair, can we then, please,
turn to the next page, page 62.[24]
I think it is probably best if I leave you to pick out the points
in relation to this page of the report which you think are significant.
(Professor Mair) Yes, what I am going to do
now is describe the essential features of the Phase 3 Stage 1
assessment and we are using here as an example the 17 to 25 Wilkes
Street structure. What I want to draw your attention to here is
really this is the summary sheet. We will go into a bit more depth
in a few moments, but this is the page which summarises the overall
result and the building response just above the table here is
the important part to look at, which summarises that the maximum
settlement that is assessed is 26mm. That is saying that if conservatively—and
that is a very important point—the 1.7 volume loss were
to occur, by the time both tunnels had been constructed, the maximum
settlement predicted would be 26mm and the maximum tensile strain,
which is the really critical parameter, would be 0.024 per cent.
That, if you recall, was also shown on the graph I showed a few
minutes ago for the Spitalfields area as being a general maximum
tensile strain predicted for a building. So 0.024 per cent being
the maximum tensile strain predicted, you can see that is well
within the negligible category of damage because the tensile strain
falls within range between 0 and 0.05 per cent, about halfway
along that range.
4122. MR MOULD: Thank you. We now turn
to two cross-sections I think which you want to comment on. First,
page 64.[25]
(Professor Mair) This is going into more detail
in the report and I will not trouble you with every number on
the table at the bottom, but it illustrates in the top part of
the page a highly exaggerated scale, I should emphasise, of the
settlement plotted. This is the settlement scale on the right-hand
side and it shows the building, which is 17 to 25 Wilkes Street,
is just over 30m in length, that is the terrace of houses, and
you can see the two tunnels where they lie. This is the depth
plotted on the left-hand side, so they lie around about 35m below
ground level and the red line in a highly exaggerated form is
plotting the total settlement arising from both tunnels having
been constructed, assuming the conservative figure of volume loss
of 1.7 per cent, which you can see is in the table listed down
here, 1.7 per cent for tunnels number one and tunnels number two.
This shows in this case the maximum tensile strain predicted in
the building is 0.019 per cent and you might recall that the overall
maximum value predicted in the assessment of this building is
higher, 0.024 per cent I mentioned, and there is a reason for
this, which I think is best illustrated in the next slide.[26]
In some ways it may seem counter-intuitive, the building is subjected
to a slightly higher maximum tensile strain when there is only
one tunnel having been constructed and if this tunnel was constructed
first, the building is more subjected to hogging deformation.
You may recall I described the difference between hogging and
sagging deformations and in this case when there is a single tunnel
only and if this one was the one constructed first, the building
would suffer a very slightly higher maximum tensile strain of
0.024 per cent compared with 0.019 per cent when both tunnels
had been constructed. This is simply to illustrate that this assessment
process is quite detailed. It looks at the effect of not just
both tunnels having been constructed, but it looks at whether
or not it might be critical, or more critical, if only one tunnel
is constructed and this happens to be the case in this example.
4123. CHAIRMAN: But both the tunnels
are not built at the same time?
(Professor Mair) No, indeed.
4124. So there is going to be a period between
them before the full impact occurs?
(Professor Mair) That is correct and what
this shows is that if this tunnel was constructed first as opposed
to the other one, that is going to be over here and I should say
that the sequence has not yet been determined and that is a matter
for the detailed design. If this one was constructed first, the
building would suffer a maximum tensile strain. The highest value
it would ever experience—I am talking about very low values
of strain here—would be immediately after the construction
of the first tunnel and when the second tunnel was constructed
it actually alleviates that strain, which I think you can probably
imagine it causes the building to go more into the sagging mode
and less into the hogging mode. That is probably the simplest
way to explain it.
4125. CHAIRMAN: The damage is likely
to be so slight that there is not a particular problem about it,
but if it was going to be much worse, you would not do repairs
in between the two tunnels?
(Professor Mair) Probably correct, yes.
That is right, yes.
4126. MR MOULD: My Lord, I notice the
time.
4127. CHAIRMAN: Have I missed it again?
4128. MR MOULD: I mention it now because
this evidence really falls into two parts. The first is what we
have just had, which is really scene-setting in relation to Mr
Wheeler's point, and we are now going to come on and address his
principal point which, as you will recall, is to do with the question
of internal inspection.
4129. CHAIRMAN: Yes. I think it is a
good moment to break and we will come back at half past two.
After a short adjournment
4130. CHAIRMAN: If there is anybody from
the Spitalfields community who wants to listen to this, there
are a number of points taken in the Petitions about the funding
for Crossrail and consequent blight if it does not happen. I am
told that the Chancellor has just said that the funding for Crossrail
is secure, as part of his Budget speech, so I fancy we will not
be troubled with that point in the Petitions. On with Professor
Mair, please.
4131. MR ELVIN: Could I just raise one
short matter before Mr Mould and Professor Mair resume. Just with
regard to the programme for tomorrow, your Lordship and the Committee
have been very clear to exclude evidence so far on alternative
alignments. We have a clear statement from Mr Horton for tomorrow
that he is going to call Mr Schabas to do precisely what the Committee
has excluded to date. If Mr Schabas is to give evidence, I am
slightly concerned about inconsistency with those that have been
excluded. It is a matter for the Committee at the end of the day,
but the Committee have excluded those who wanted to raise those
matters in very firm terms up until now. If Mr Schabas is to give
evidence—
4132. CHAIRMAN: I have got no idea what
he is going to say.
4133. MR ELVIN: Well, I do because I
have seen a recent email from him. He is going to promote the
southern alignment.
4134. CHAIRMAN: How?
4135. MR ELVIN: Well, I do not know.
I simply raise that, and of course I will have to deal with it
in Mr Horton's presence when he is here tomorrow. The reason I
raise it is that we have a slight potential practical difficulty.
Mr Berryman unfortunately has had to take to his bed. He has a
chest infection. He hopes to be here tomorrow, but, for reasons
I will not trouble the Committee with now, he needs to be here
if Mr Schabas is giving evidence. Can I report back to the Committee
later on this afternoon when I have more news?
4136. CHAIRMAN: I do not want to rule
witnesses out in advance before I have heard what they say.
4137. MR ELVIN: I appreciate that, my
Lord, and I would not ask you to do so in Mr Horton's absence
in any event. I just flag it up now because we have a potential
problem for tomorrow, but I hope we can resolve that before the
end of the afternoon.
4138. CHAIRMAN: Well, tell us how it
gets on. Now, more points for Professor Mair.
4139. MR MOULD: Professor Mair, we are
now going to turn correctly to the issue which was raised yesterday
by Mr Wheeler, that is to say, the consideration of the sensitivity
of listed buildings within the Spitalfields area as part of our
settlement assessment process in the reports which were prepared
by Alan Baxter and Mott MacDonald in conjunction. Yes?
(Professor
Mair) Yes.
24 Crossrail Ref: P23, 17-25 Wilkes Street, listed
Building Assessments, Mott MacDonald (TOWHLB-XR5A-062) Back
25
Crossrail Ref: P23, Settlement Analysis Summary, Final Configuration-Both
Tunnels (TOWHLB-XR5A-064) Back
26
Crossrail Ref: P23, Settlement Analysis Summary, Critical Configuration-Westbound
Tunnel Only (TOWHLB-XR5A-066) Back
| 
