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Geotechnical News • March 2016
GEOTECHNICAL INSTRUMENTATION NEWS
• The need for PE or GIE stamp
might apply to the structural or
geotechnical engineer, within the
United States tradition of protect-
ing local borders. It certainly does
not apply to RTS specialists, in my
opinion.
I have another comment about the
RTS specialist: Running a monitor-
ing program with high quality results
is so specific, even more so when
using RTS, that I would recommend
not experience of two projects, but
ten if possible. Of course one wants
to receive at least three offers, so a
request for such extensive experience
might be a little too drastic and could
be reserved for large projects.
The
“
by whom
”
question
On the subject of the “by whom”,
I believe the key points are about
procurement and the structure of
the contract. Procurement must not
be based on low cost, and it should
target companies with experience and
reputation, etc… By “structure of the
contract” I mean the question of who
the monitoring specialist works for:
the main contractor, or the engineer-
ing firm, or the owner. All these
points have been discussed in detail in
previous episodes of GIN, so I will not
repeat them.
Specification key points
If we think about the main items
required to obtain good instrumenta-
tion and monitoring (including RTS)
specifications, I would recommend:
1. Define clear objectives in terms
of what engineering values are
needed, with what precision and at
what frequency. These objectives
should be defined by a geotechni-
cal or structural expert, to suit
exactly the project needs, and
no more no less than the project
needs.
2. If possible, give liberty to the
specialists to select the monitoring
system that they will use to answer
these objectives.
3. Define how the specification, and
especially the precision, will be
controlled. This is not an easy task,
and could the subject of a com-
plete paper. But it is absolutely
necessary.
4. Insist on the fact that the specifica-
tion will be enforced, and detail
the contractual consequences of
not matching the specifications.
Thinking about it, we are not far from
the SMART theory: Define specifica-
tions that are Specific, Measureable,
Achievable, Relevant, Time defined.
Some comments on Figures 3
and 4
Finally, I will finish with some minor
technical comments about figures
3 and 4. Figure 3 appears (I am not
100% sure, as the vertical scale
appears to be masked around 0, or
highly non-linear around 0) to show
some RTS data of fairly low precision,
with a lot of noise and quite a few
spikes. There can be many explana-
tions for such data, such as a very
complex measurement conditions, the
total station far from the targets, or
other such real-life difficulties. How-
ever I would not want readers to think
this is the standard in RTS results.
Maybe the cause can be found in the
configuration shown in figure 4, where
clearly it was not possible to achieve a
proper topographic layout.
Martin Beth
Technical Director
Soldata Group
3120 Route d’Avignon
13090 Aix-en-Provence
France
Email:
Joel Volterra
Thank you to the authors for address-
ing a subject that I believe worthy of
periodic reexamination and ongoing
discussion. Before addressing the Pro-
fessional Engineer (PE) versus Profes-
sional Land Surveyor (PLS) issue,
I’ve added a few related matters that
I believe factor into that very issue,
hoping at the same time it doesn’t
cloud the issue. I’ve seen this discus-
sion center on the role of the techni-
cian versus the role of the Engineer in
undertaking the tasks which together
comprise these complex instrumenta-
tion and monitoring programs, spe-
cifically including the now prevalent
use of robotic total stations (RTS) or
automated motorized total stations
(AMTS).
Data interpretation requires
knowledge of construction
progress records
My and my colleagues’ philosophy
has been to minimize the separation
of implementation, collection and data
reporting from data evaluation and
interpretation. Construction prog-
ress records are necessary for data
interpretation and evaluation. In the
writer’s experience all too often the
two are not submitted together, and
thus acknowledging a designed-for or
anticipated movement or lack thereof
as a function of adjacent construction
activity is lost. This undermines the
value of the monitoring program as
a whole and diminishes its intrinsic
value of collaboration among owners,
contractors and consultants undertak-
ing the work, whether performed by a
PE, PLS or a technician under direc-
tion of one of the former.
Who is best suited to evaluate
data?
Where an engineering analysis or
structural computation estimates
