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Tight design tolerances on a big roading job in Auckland saw contractor HEB return to Global Survey for its latest Leica PowerGrade 3D system.
The Hobsonville Deviation will feature five interchanges, five bridges and four roundabouts, and make provision for bus shoulder lanes, resulting in local roads being safer and less congested. HEB is currently working on preparing the subgrade and basecourse in anticipation for sealing, which has now started. Tolerances on this job are tight so HEB is using a Leica PowerGrade 3D system from Global Survey. “We got a Leica grading system for a project we had at Mangatawhiri three years ago and it did an excellent job for the levels, so we got a second one for this project,” says HEB contracts manager Doug Morgan. “It’s a big job so we’ve got both systems working on graders at the Hobsonville site. “We can get within 5mm of the design and we save a lot of down time without having to do any stringing and by putting in fewer pegs. We have a peg every now and again to double check the levels but that’s just for quality assurance purposes.” Global Survey general manager Ray Copeland says the Leica PowerGrade 3D system allows the engineering design to be uploaded and then it controls the hydraulics of the grader automatically to achieve the design to within 5mm regardless of how complex the design is.
The 3D system doesn’t just allow the operator to get it right, but to get it right first time. It means fewer passes with the machine to achieve the final grade, meaning less wear and tear on the grader, less fuel consumption and everything gets done a whole lot faster. Doug has noticed a few improvements in the latest system on the three-year-old one. “It’s easier to set up than the older one – a bit more user friendly.” This is because the new system is wireless, using induction to connect the control panel to the unit. “There’s nothing to unbolt,” says Ray. “This makes it easier to take the control panel out at night for security reasons – you don’t have cables floating around in the cab. It also makes it very fast to move the control panel between machines like dozers, graders and excavators as its designed to be interchangeable.” The other obvious improvement are the graphics – the latest version allows the operator to see the design data in 3D on screen.
As far as HEB is concerned, one of the best features of the Leica system is the support the team receives from Global Survey. When HEB first purchased the 3D system, machine control specialist Gordon Inns did the installation and operator training, but it didn’t stop there. “We get excellent service from Global Survey,” says Doug. “They are really helpful to me. All I have to do is make a phonecall and they’re there with the answers. And it doesn’t matter if it’s night or day – I talked to Ray last night at 7.30, and he’s happy if I call him on the weekend, which is great as we’re working seven days a week up here when the weather lets us.”
Contractor Vol.34 No.6 July 2010 |
Work on the $220 million Hobsonville Deviation began in September 2008 and is due to be finished in 2012. It’s a massive undertaking, being built by HEB Construction, and consisting of a six kilometre, four-lane motorway from Hobsonville Road to the end of the Upper Harbour Bridge and a three kilometre, four-lane extension of the Northwestern Motorway from Hobsonville Road to Brigham Creek Road in Whenuapai.
“What this system also allows is for the operator to put the blade in any position – there are no restrictions in having to have the blade vertical,” says Ray. “This allows the operator to freely work with the material he’s grading without losing accuracy or performance. It’s not necessary for surveyors to set the equipment up, the grader operators do it all themselves.”
Ease of uploading design information is also key. “You simply plug in a USB key,” says Ray. “It will accept data in any industry-standard format.”