| OTIA III State Bridge Delivery Program |
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| Web Brief (Jan 07) |
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Grading is made easier through use of technology.
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Technology helps grading contractor work faster and smarter
The numbers say it all.
“When we put a machine-control system on our graders, we saw a 300 percent increase in productivity, a 50 percent savings on engineering costs and a 10 percent savings on materials,” said Julie Gillett, co-owner with her husband, John, of Grading Unlimited Inc. of Hillsboro, Ore. “Sometimes this is the edge you need to be successful on a project bid.”
On the OTIA III State Bridge Delivery Program, Grading Unlimited is achieving these cost-effective and efficient results by using a machine-control system to place and grade aggregate base on a critical project in Salem, Bundle 212, Interstate 5: North Santiam to Kuebler Boulevard.
The traditional way of staking and grading a site requires foot-long wooden stakes and an accurate aim on the part of the grader operator, who must maintain a plane that can’t vary more than the width of a pinkie finger. Setting stakes precisely is still an essential part of the initial site-excavation and the final paving. But the interim process—placing aggregate and grading it to create an even base for the asphalt surface—can now be done using systems that automatically control the grading equipment. Computer-aided design surveying technology makes the work of placing, compacting and finishing the aggregate base quick and accurate.
Machine-control automation relies on digital 3D models of a site or corridor developed by the design engineers. A computer on the grader then interprets the resulting digital terrain model, and a sensor attached to the grader regulates the height of the blade to achieve the desired grade.
Though the machine-control process is used extensively in other types of construction, it is relatively rare in transportation work. Oregon is one of only a few DOTs nationwide to use the technology.
“Tighter budgets and schedules are pushing design engineers and construction contractors to rely on cutting-edge technology during all phases of design and construction,” said Ron Singh, ODOT chief of surveys. “Machine-control automation represents a significant savings in both time and money.”
Because Grading Unlimited no longer needs to hire a crew to drive stakes for its portion of the process, the company can operate with only two people: John places the aggregate, and Julie runs the roller. Once a site has been graded, ODOT surveyors review the finished product against the digital 3D model to ensure that the specified tolerances have been met.
“We’re always looking to work with contractors who are ready to take advantage of the latest technologies,” Singh said. “Grading Unlimited’s high-quality and efficient work has made them excellent partners on this bundle.”
## ODOT ##
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