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Better Grades for a Brighter Future
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Better Grades for a Brighter Future

The importance of an accurate grade before adding base and finishing materials is hard to overstate. Without it, contractors have to compensate by using more aggregate, concrete, asphalt, etc. thereby increasing their overall project costs. In more severe cases, materials already put down have to be removed and replaced. Grade control technology is designed to prevent this by helping ensure a more precise grading job.

Better Grades for a Brighter Future

For this grading solution, a box blade attachment from Level Best is connected to the front of either compact track loaders or skid steers and can be configured with a laser system or a full 3D system. For the 3D solution, a Topcon, Trimble, or Leica system, which includes 3D GNSS (Global Navigation Satellite System) receivers, is added. This solution also allows the use of an engineered 3D design plan, which is easily uploaded into the system.

Getting good grades - that was something most of us were implored to do by our parents, teachers and others. In the construction industry, good grades are just as desired, though not in the same sense of course. And just as technology is helping students improve their performances in schools, it is also vastly improving the performances of the operators and machines that grade the ground on a construction project.

According to Scott Hagemann, who is a technology specialist, global construction and infrastructure for Caterpillar Inc., the primary functions of grade technology systems is to either "guide operators to target grade," usually through a visual display in the cab, or to "go a step farther and control the blade or bucket automatically, eliminating or greatly reducing manual effort."

This technology is available for the big roadwork machines like dozers and scrapers but more and more it is being integrated into the machines that landscape contractors favor such as skid steers.

For example, Sean Mairet, John Deere's product marketing manager, grade control, told LC/DBM that onboard grade indication has just become available on the company's large-frame, G series skid steers and track loaders.

"Through the integrated monitor, you can quickly review your machine grade in real time," relates Mairet. "The versatile system provides both cross slope and mainfall information using either a locally referenced surface or a level plane. The locally referenced surface option is useful for altering grade on an existing surface: for instance, if you wanted to put a two percent slope on top of an already existing two percent slope. The machine provides information on what your slope is, both in an absolute sense and a relative sense."

The system uses an inertial measurement unit, an electronic device that sits on the machine and reports information such as angular rates. The information is then processed on board and displayed in the cab so an operator can check his work without leaving the cab. This allows the operator to see if the ground has been made flat or correctly modified to the desired slope.
Besides coming out on newer machines, some systems can be added to older models too. Cat Grade, which Hagemann says can result in efficiency gains of up to 45 percent, can be added to most machines regardless of brand or age.

Better Grades for a Brighter Future

With on-board grade indication, an entry-level type of grade control technology available on the 330G and 332G skid steers, and the 331G and 333G compact track loaders, the operator makes all the grading decisions based on the information from a sensor that indicates the slope of the machine.

Better Grades for a Brighter Future

Caterpillar's CATA(R) Grade Assist is 2D technology integrated into a machine. Instead of needing a base station or relying on GPS equipment, a flat plane laser is used as a reference. The manufacturer states their grading technologies can result in efficiency gains of up to 45 percent and pay for themselves in about 6 months.

This system can be operated in 2D mode, for flat planes and slopes, or 3D mode, which "handles contours and complex curves," Hagemann states. He goes on to explain other differences in the two modes.

"2D uses an external point of reference like a curb or laser; 3D references an external infrastructure for reference and an internal machine digital site plan. 2D needs less infrastructure than 3D (such as) experts, base stations, total stations, data radios, designs. 2D is less expensive - and fits fewer applications (but) works well when job conditions are fairly stable; 3D is preferred when the work is always changing."

There are third party options available also. Andrew Kahler, the product marketing manager for John Deere Worksight and Forestsight says that his company's dealers can offer their customers a product from Level Best - a box blade attachment that is attached on the front of either compact track loaders or skid steers and can be configured with either a laser system or a full 3D system.

In the first configuration, an external rotating laser is set up for the desired grade. Its beam is read by laser receivers mounted on mast poles on the attachment, which also has a control panel that interprets where the beam is in relation to grade, and then tells a hydraulic valve to adjust the grading box up or down. This happens many times a second.

For the 3D solution, a Topcon, Trimble, or Leica system, which includes 3D GNSS (Global Navigation Satellite System) receiver, is added. This solution also allows the use of an engineered 3D design plan, which is easily uploaded into the system.

"That is where grade control really shines, in that you can still maintain tight tolerances even with complex 3D design plans," Mairet relates.

Better Grades for a Brighter Future

With Grade Assist for excavators, the depth and slope are set into the system and then digging is accomplished with a single lever as the technology automates boom and bucket movements for more accurate cuts with both standard and rotating attachments.

Better Grades for a Brighter Future

Besides improving the speed that a job gets finished, grade control technology also lets the operator be more effective with the skills that they have. Kahler states that this is particularly important with compact machines "because often times they are used in tight areas and finesse jobs where accuracy of the job is critical."

The operator can look at a monitor to see what is coming up and to be able to steer the machine in the most optimal path, making small tweaks and adjustments here and there.

As for productivity improvements with their systems, Kahler states, "We know on larger equipment we can see 20 to 30 percent improvement in productivity with the use of grade control technologies, simply because operators don't have to make as many passes, and are able to get the job done more quickly and accurately. They are able to hit the final grade closer than if they were trying to do it by hand. I would expect that trend to hold on smaller equipment."

Compact excavators can also be outfitted with grade technology. Hagemann reports that CATA(R) Grade Assist is one system that is available.

Kahler says that his companys dealers offers a third party solution. "We have a number of dealers who are also selling grade reference kits for compact excavators, which allows the operator to understand where the cutting edge of the bucket is with respect to either a laser plane or to a 3D global design."

The process of grading a site has come a long way since using stakes pounded in the ground to identify and achieve target grade, with workers on the ground to assist. With the new technology, it can be done faster in fewer passes, with more accuracy, while using material more efficiently, burning less fuel, possibly easing the skilled worker shortage, and, with fewer workers on the ground potentially in the paths of the machines, improving site safety, which might be the most important benefit of all.

As seen in LC/DBM magazine, October 2018.

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February 17, 2020, 1:44 pm PDT

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