Summary
Main Roads Western Australia has drastically cut its road planning and
associated preliminary design timetables by using 4D Model software (later
renamed 12d Model).
The Rural Planning and Strategies branch of Main Roads recently used 4D Model
to complete the initial preliminary design of the 128 kilometre, Marble Bar to
Woodie Woodie Road, via the Ripon Hills route. The design project took only four
weeks as opposed to the 18 months required by a similar, earlier project.
Mike Darmody, Planning Co-ordinator for the Rural Planning and Strategies
branch said 4D Model had been used on numerous preliminary design jobs since
being introduced in 1992.
"It has culminated in this large road building task where 4D Model really
came into its own," said Mr Darmody.
The Challenge
"When we were developing the Newman to Munjina Gorge section of the National
Highway, which was approximately 150 kilometres long through very similar
terrain to the Ripon Hills route, the planning and preliminary design phase took
18 months, utilising the best available technology at the time."
The Ripon Hills route had been a dormant road proposal for 10 years but was
fast-tracked by the WA Government after intense lobbying by mining companies
which have used the existing gravel road to transport minerals and fuel.
The road is regularly closed, due to flooding, for up to six weeks a year and
is described as a maintenance nightmare.
The new road, currently budgeted at $32 million, will carry a potential of
550,000 tonnes of mining products per annum. It will also benefit tourist
traffic that is expected to explore the area when the road opens.
"The job probably would normally take four years to complete, for that length
of road through that type of terrain," said Mr Darmody. "But the urgency of the
requirement means it has to be fast-tracked to a two-year time frame and
completed by November 1997.
The Solution
Mr Darmody believes the user-friendly nature of 4D Model has enabled his
branch to usher in new road planning and design techniques resulting in reduced
project timetables.
"The need to prepare time consuming, detailed, final design drawings months
in advance of road development projects in the remote areas of Western
Australia, are gone. "The Ripon Hills project will be achieved using design and
construct techniques that will basically enable us to design the road one day
and build it the next . This process is an extension of how roads in the Pilbara
and Kimberley regions were built in the past; they were surveyed the day before,
drawn up and designed in the camp that night, and final construction levels were
handed out to the foreman the following morning."
A road’s vertical design profile largely dictates a road’s construction costs
so the ability to quickly recalculate vertical alignments enables 4D Model users
to monitor project costs.
"We can achieve a lot with the road’s horizontal locations, such as trying to
achieve a 110 kilometre per hour design speed," said Mr Darmody.
"But it is the impact this high speed design has on the road vertically that
dictates the cost of the project. This is reflected in the depth of cuttings or
heights of embankments and resulting road gradients. A tourist access road can
get away with ten per cent gradients but a mining access route with high road
train volumes can handle no more than five per cent over short haul distances.
"If there is a need to change any of the alignment on the Ripon Hills route,
the user-friendly capability of 4D Model for on site applications is going to be
advantageous. If, as construction of the road proceeds, the project engineer is
confronted with adverse geology or drainage that was not originally anticipated,
the road design can be adjusted on site. Associated changes in road earthwork
quantities are also recorded."
The Result
Mr Darmody believes 4D Model will also assist with the planing of a future
major realignment of the National Highway, North of Perth. The proposed route
bypasses areas that have attracted people seeking alternate lifestyles away from
Perth.
"4D Model cadastral lot boundaries as well as the topographical model. If a
person’s lot is going to be impacted by a major road realignment we can call up
the legal position of a person’s lot and superimpose the alignment on top of
this lot. "Because we have the capability of moving the alignment around and
adjusting our vertical profile at the same time, we can show the impact the road
will have on the property.
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