Home' Position : Position Jun Jul 2015 Contents Therefore all the observations had to be
extremely accurate and had to correct for
changes in the environment. However, it
was very difficult to monitor temperature
in the tunnel, because the atmosphere was
not constant throughout the 24-hour cycle.
During the day, the buses were stirring up
the air, but at night it settled into different
layers. In addition, the tunnel's exhaust
fans were switched off at night.
"We had to observe the total stations
observations through layers of different
temperature," said Mr Hellen. "This
presented some difficult challenges in
terms of vertical angle refractions for the
observations. To solve this problem, we
isolated some of the alarms at different
times of night during the project, to allow
for the unpredictability of atmospheric
effects that we could not control."
Additionally, to help maintain the
precision of the observations, the tunnel
operators agreed to run the fans at night,
which kept the atmosphere constant.
A separate challenge was the extent of
the communications required to provide
the data to the customer in real time,
reliably, and constantly for a year.
Finally, Mr McIlwraith pointed out,
there was the challenge of "liaising with
the different departments to put the
monitoring plan in place and to insure
that there was no negative effect."
Serving the data
All of the sensors were connected to an
outside server, which ran Trimble 4D Con-
trol software (T4D).
"One of the real challenges that
made this project quite unique was the
way in which we served up the data
to our client," said Mr Hellen. "This is
accomplished by means of a web-user
interface, desktop software, and SMS and
"It would have been highly problematic
to send data directly from the total station
in the tunnel to the server by radio. So,
instead, it is sent to an adjacent com-
munication box that converts it to a TCP/
IP format. The output from that box is
then sent along the bus tunnel, through
about 100 m (330 ft) of Ethernet cable, to
a radio housed in another communication
box positioned for a clear and uninter-
rupted signal to another radio located
across the rail lines and the excavation,
about 150 m (490 ft) away from the server.
"The second total station, which is on
top of a 15-story building, has a direct
radio link to the server. Three on-site
field data loggers use GSM modems to
send the data to an on-site server and
900 MHz radio connections control the
total stations through a Trimble Pivot
infrastructure software platform," he said.
Managing data and alarms
Watpac engineers access the monitoring
data via a web-user interface from the
T4D software. It enables limited access,
if needed, to control the alarm levels, and
it determines who receives which alarms.
For example, some engineers might
be interested in certain geotechnical
data, but not in the data from the total
stations. Depending on the severity and
type of the alarms, the T4D software
automatically sends SMS or e-mail
messages to specific contacts, so users
can log in at any time and determine the
legitimacy or severity of the alarm.
The T4D web-user interface also
allows Watpac's engineers to analyse the
data, look at trends and data for periods
of their choice, and plot various data
types against each other. The monitoring
system effectively measures movement
over time in horizontal and vertical axes.
The geotechnical data is sent as a DAT
file via the 3D data connection from the
data logger on site to a server, where it
is ingested by the T4D software, which
automatically processes the data and
provides analysis output.
According to Mr Hellen, every day
the survey equipment delivers 8,400
measurements and the environmental
and geotechnical sensors deliver possibly
tens of thousands of observations. The
public stakeholders can access all of them
via the web portal. The site is updated
automatically, and key people regularly
access it 24 hours a day to analyse the
data for specific purposes. This sets a new
benchmark in the way construction sites
can be monitored.
"We are using the data daily during
the excavation to monitor, because things
are moving," said Mr McIlwraith. "For
example, by monitoring the data, we
can ensure that the beam on top of the
piles is moving within the calculated
Analysing the data
The monitoring data is analysed in real
time through the Trimble Pivot platform,
which collects the data from the field,
processes it, and then sends it through to
the database. The database then serves it
up online to be viewed and analysed.
T4D was configured by Land Solution
Australia to include standard reports,
as requested by the engineers, and
allows them to customise the reports,
should they wish to create their own.
The engineers on site, who are required
"The presence on the Southpoint Development site
of an active transportation hub, including one of the
busiest stretches of railroad tracks in Brisbane, gave
Land Solution Australia the opportunity to create a
fully-automated geospatial ecosystem to best serve
the needs of their client."
in the tunnel.
24 position June/July 2015
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