The heavily trafficked three-mile-long Wairakei Road
is an urban two-lane road that was twisted and contorted
in the main earthquake.
3D Milling
Meets the
Challenge
Repairing earthquake damaged road in Christchurch NZ
By JEFF Winke
W
hen the February 22,
2011 Christchurch City
earthquake erupted, this
powerful natural event severely damaged New Zealand’s second-largest city
and has been described as one of the
nation’s worst peacetime disasters. To
add context, the Canterbury region had
been experiencing earthquakes since
the September 2010 Darfield event,
with over ten thousand recordable
earthquakes to date.
One significant road damaged in the
quake required the Christchurch City
Council’s (CCC)’s immediate attention.
The heavily trafficked three-mile-long
Wairakei Road is an urban two-lane
road that got twisted and contorted in
the main earthquake. Wairakei Road
Displayed with permission • Machine Control Magazine • Vol. 3 No. 2 • Copyright 2013 Spatial Media • www.machinecontrolonline.com
“We were sure that using Fulton Hogan’s milling hardware, teamed with the Trimble 3D control
system, would deliver the best possible surface with the least disturbance to the road user and
neighbouring resident,” states Tim Clark, Fulton Hogan’s Canterbury surfacing manager.
is about 19 miles from the epicenter of
the 6.3 Richter magnitude earthquake,
which was in Lyttleton.
Key to the reconstruction of Wairakei
Road was milling the heavily-damaged
road to prepare it for resurfacing.
Timing was critical since this main arterial needed to be unimpeded in the early
morning from 7am to 9am and again
from 4pm to 6pm to accommodate
Christchurch commuters.
Fulton Hogan, a leading Australasian
civil contracting company with 5,000
employees, was engaged by maintenance
contractor, City Care, to undertake the
road milling and preparation work for
asphalt paving. As a leading provider
for the CCC, Fulton Hogan understood
the importance of their role in the
reconstruction of the city.
“Our original thought was to mill the
top 30 to 40 millimeters off, but the road
had slumped and heaved so much that
it would have remained an unacceptable
ride when completed,” said Tim Clark,
Fulton Hogan’s Canterbury surfacing
manager. “Instead, we proposed the
accommodating the extremely uneven
surface in order to quickly return it to
the acceptable baseline for resurfacing.
“We knew that traditional milling
to design would be prohibitively slow
when milling such a surface,” says
Clark. “We were sure that using Fulton
Hogan’s milling hardware, teamed with
the Trimble 3D control system, would
deliver the best possible surface with the
least disturbance to the road user and
neighbouring residents.”
With the help of its local Trimble
dealer, Fulton Hogan installed the
Trimble GCS900 system on its Wirtgen
W1200 cold milling machine. Both parties have worked to perfect the system
for such a use, and it is now considered,
by many, as an integral part of delivering
industry-best results.
The Wirtgen W1200 is a 20-tonne,
cold-plane, milling machine, manufactured in Germany, which runs on four
tracks with independent height control.
The ability to control the height at each
corner of the machine allows predeter-
The Trimble 3D milling system is designed to
make it possible to mill surfaces at variable
depth and slope without string lines. Trimble® GCS900 system with Fulton
Hogan’s milling machines, so that we
could mill to a design ensuring a smooth
surface for paving.”
Fulton Hogan stated that the
Trimble technology was critical for
mined surface profiles to be produced.
This machine is designed to remove a
1200-millimeter wide 300-millimeter
deep cut in a single pass.
The Trimble 3D milling system is
designed to make it possible to mill
Displayed with permission • Machine Control Magazine • Vol. 3 No. 2 • Copyright 2013 Spatial Media • www.machinecontrolonline.com
surfaces at variable depth and slope
without string lines. By controlling the
precise cutting depth of the mill, the
technology minimizes over-cutting,
creates a smoother surface, and reduces
the need for additional asphalt in the
ensuing resurfacing process.
“Our mandate was to complete
the work as accurately and quickly as
possible, getting traffic back on the
road,” Clark says. “The Trimble system
helped us cut the construction period in
half when compared to using traditional
methods. We also saw a reduction of
direct cost to the client, and minimized
disturbance to stakeholders”
Clark quickly added that another
significant benefit of using Trimble
machine control was it ensured a safer
work environment, by reducing the
number of staff required to undertake
the work with live traffic.
The project site was 120 meters long
and approximately 8-9 meters wide, so
Clark felt this machine was well-suited
for the task.
There was no project design provided,
so Fulton Hogan’s surveyor Darren Maw
arrived early at the site on the first day
and using a Trimble SPS930 Universal
Total Station was able to capture the site
data. Then, using Business Center—HCE
from Trimble, he was able to create a
digital site plan. Maw said he was able
to create the digital design within a few
hours, “the project was relatively straight
forward from a design perspective, all
we really needed was to make sure that
the geometry was right as far as the
surface, centerline, and where any water
would drain. So it was really just a case
of picking up the curbs and developing it
from there.”
Fulton Hogan literally began
milling the road by mid-morning and
With the help of Trimble technology, Fulton Hogan literally began milling the road by midmorning and completed it by early afternoon, meaning asphalt could be laid the next day.
completed it by early afternoon meaning
asphalt could be laid the next day.
“The paving contractor was able to
use our digital model to determine
paving depths,” says Clark. “We milled
the road to grade achieving a smooth
paving surface and allowing a nominal
thickness for the entire site. Only
existing services fell out of spec, so we
painted numbers to provide guidance
for the paver team.”
The project went very well and was
completed in less than two days. “We
were able to complete the job quickly,
accurately, and with fewer staff
because we were using the Trimble
system,” says Clark.
With the resurfacing completed and
traffic flowing, Clark now reflects: “In a
very short construction period, under
significant pressure we took a severely
deformed road surface and milled it to
grade using a model which we created.
The quality of Fulton Hogan plant,
the technology provided by Trimble,
teamed with the aptitude of Fulton
Hogan’s staff resulted in an incredibly
smooth ride. We’re extremely happy
with the results and know that the
commuters appreciate it too.” MC
Jeff Winke is a business and construction
writer based in Milwaukee, Wis. He can be
reached through www.jeffwinke.com.
Displayed with permission • Machine Control Magazine • Vol. 3 No. 2 • Copyright 2013 Spatial Media • www.machinecontrolonline.com
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