NSW Council pushes the envelope with Topcon machine control
Forbes Shire Council, in the central west of NSW, has been a pioneer among local government in the state in its use of GPS-based surveying and machine control systems – a move it has found has paid off in terms of efficiency and speed of works.
Based around the town of Forbes, located about 400 km west of Sydney, the shire services a population of just over 9,000 people.
Over the past five or six years, it has pioneered the use of GPS-based systems among NSW councils for its survey works, and as a result of the efficiencies and successes it achieved, has since moved into machine control systems for its road construction equipment.
According to design engineer Graeme Isbester, the council started using lasers and 2D machine control in about 2004, then moved into GPS-based systems five or six years ago.
Today it owns a significant number of Topcon systems, including two 3D machine control systems for its graders, plus Millimetre GPS add-ons, a Topcon LegacyE base station, along with repeaters, GR5 and GR3 receivers used as base stations or rovers, plus one HiPer+ rover.
High performance, automated 3D-MC2 for grading
The Komatsu grader which Forbes Council uses for RMS works has recently been fitted with Topcon 3D-MC2, which was purchased with the intention of improving road ride quality. Under the RMCC contract between FSC and RMS, superior ride quality may attract monetary bonuses and below standard ride quality may attract penalties. It is therefore in Council’s best interests to achieve the best ride quality possible.
With this equipment, the majority of the shire’s survey works, including construction and maintenance, along with stockpile measurements, are now carried out using Topcon GPS systems.
“We love this, being surveyors,” said Graeme.
“Usually there is no set out needed and, provided we get the model right to start with, it’s great; we just do a check every so often.
“We’ve learnt over time how we need to set the jobs up a bit differently than we would with a total station and it all runs pretty well now,” he said.
“For example, to start with, we weren’t aware that you could take a 20-30 second observation instead of the usual 3-5 sec shot with GPS to increase the accuracy, so we tended to use the total station more to start with.
“But now we hardly use our old total station at all after learning a few tricks with GPS,” Graeme said.
The council hired its first Topcon rover in about 2007 for a project, purchasing the same unit for its next project.
Work carried out by Graeme’s team includes DTM and point setouts, detail level conformance for RMS works and measuring stockpile volumes for six monthly returns for the council’s gravel pits.
Forbes Shire’s graders and machine control systems are used for carrying out road construction, both for the council’s own works as well as on RMS jobs.
“For our machine control operations, we just load the design into the Rover and the grader, we do a few checks and make sure we’ve got the grader setup right and it then usually runs without a hitch,” he said.
Saving time with more streamlined workflow
“In the past, when we were constructing say a 300 mm overlay on a road, we would have to go out and work out tipping rates so that they could get the correction course right before they could construct all the pavement layers. Then they’d have to repeat that for the next three layers.
“Now with machine control, the grader driver knows when he is 300 mm below finished surface level, so he just moves material around and imports material until he has achieved the subgrade level, then he knows he can lay out the pavement material in even layers.
“They find the whole process much easier too – plus at the end of a day’s work, they can lay the material down instead of leaving it windrowed along the edge of the road like they used to.
“They can lay it down knowing how it compares with the levels they are after – and it makes the jobs safer because there are no windrows sitting alongside the roads at night.
“Our operators just lay the material down and give it a quick roll at the end of the day; they know that the road has got the correct crossfall and they know exactly how much they’ve still got to go simply by dialling up the depth,” said Graeme.
According to the shire’s construction supervisor Tim Smart, the machine control systems on its graders – a Komatsu GD655-5 and a Cat 12M – make operations much quicker for the operators.
“We don’t have to wait for the surveyors to turn up at a certain time to place pegs,” he said.
“The surveyors go and do the surveying, do the design, then plug it straight into our machines, and we’re right to go.
“It saves a lot of time and our operators like it too, because they don’t have to get out of the machine to check the stringlines and all the things they used to do.
“It speeds up our job, our process, and doing the work as well, so it is a win-win for everyone really,” he said.
Tim’s comments were backed up by operator Brian Curry.
“I’m not waiting around for surveyors and stringlines and things; they just put all the files in it, and I just go and start my work,” he said.
“It’s much more efficient; you know where your lines are and your grades, so you don’t have to rely on getting out and pegging it.
“I’d say it would cut a job to a third of the time, or a little bit more maybe.
“When you’re laying the gravel out and everything, you’re getting good results with your materials, because you’ve got it everything at the right height,” Brian said.
GPS improves on-site safety
Design engineer Graeme Isbester’s team also finds that using Topcon GPS for stockpile volumes is safer and faster than with traditional methods.
“In the past, using a total station, we’ve had to have maybe four or five stations to be able to see around the stockpile, or we have taken the unsafe practice of taking the instrument right up on top of the stockpile so that you can get the perimeter, but it is not very safe.
“Now we just walk over the stockpile with the GPS rover.
“If we are anywhere within the town limits, we use the town base station, otherwise, we set up another base station out at the stockpile site. It doesn’t really matter the precise coordinates of the thing as long as it is correct within itself.
“When we’ve walked over the stockpile, we take it back to the office and process the volumes.”
Graeme believes that Forbes is one of the most advanced among NSW regional councils in its use of GPS systems for both surveying and machine control.
“From what we’ve been told by Adam Burke from Position Partners, we are probably ahead of the field for most of NSW as far as councils go, but I think others are now coming on board, now the benefits are becoming apparent” he said.