“I’d rather have used a dozer for this small job, but we don’t have one,” comments Peter Taylor, after just finishing the grading for an additional, small parking lot at a Miami hospital. Taylor is a peripatetic construction worker who has grading experience with contractors in the southeastern United States. A big, old motor grader did the grading, with help from loaders for the tighter corners. The problem with the grader was that its hydraulics was now unreliable, its maneuverability inadequate, and its use of power insufficient for the best and fastest results. “The controls on newer machines make such a difference, too-for accuracy as well as speed,” adds Taylor. “I personally don’t like trying to grade with a motor grader on small jobs. This one is too big to maneuver easily, and I’d prefer a small dozer.”
Asking manufacturers and contractors about gradingequipment proved to be very interesting. “What kind of grading?” was the most common reaction to our initial request for opinions and advice about this vital, basic aspect of site preparation. The consensus was that grading is the technique that reduces uneven ground to levels that are flat or sloped correctly for building. Good drainage was a goal mentioned frequently. For road construction, the motor grader has been the most popular, and municipalities and counties use graders for the many thousands of miles of gravel roads and alleys in the US. But not all grading is for road construction or maintenance. Almost every construction project or site preparation requires some grading, and the machines used depend on the precision specified. The first grading at a site in northern California for new houses involved removing a few acres from the top of a hill and using the spoil to form the stable ground for the new structures about a half mile away. For accuracy at this site, the graders were fitted with a Trimble Navigation machine guidance system. This system allows a contractor to have a stakeless environment at a site, eliminating downtime while surveyors are staking and significantly reducing rework. Trimble (Sunnyvale, CA) and Caterpillar (Peoria, IL) are two of several companies that have worked together to develop better grading techniques that involve machine guidance, taking advantage of a daylight-readable display in the cab to show the operator what has been done correctly and what still needs to be done. “We keep the dozers running all the time with minimal supervision,” states engineer Erik storm, who monitors dozer operations for Glenrock Coal Company (Glenrock, WY), where accuracy and productivity have equal importance. “We don’t even stake the ground because our operators can tell in their machines where to make the next cut.” Radio communication of global positioning system information with the office virtually turns the dozer or grader into an automatic surveyor as it moves around the site.
Spectra Precision in Dayton, OH, makes the Blade-Pro control system for motor graders and says that its use can help cut the cost of fine grading by reducing conventional grading time as much as 50%. With Blade-Pro, both sides of the blade correct simultaneously, eliminating that wobbly movement called “duck walking,” and there is no jerky response when starting the grader forward or shifting gears. Control of the system is mostly by push button, while the LCD and LED grade lamps are automatically adjusted according to ambient conditions. The functions that the operator can select include remote slope and elevation offsets (good for vertical curves, multiple layers of material, or slope transitions), slope alert to warn the operator if the cross-slope was not cut to tolerance, and selectable slope units that display slope as a percentage slope or rise over run. The latter function can easily match the units specified on the blueprints. The instruments for grading from such companies as Trimble, Spectra Precision, and Topcon (Paramus, NJ) are sophisticated and accurate. They have also been welcomed by operators as simple to operate and understand. One experienced grader operator remarks, “I used to enjoy my work, but with this system, I love it!” Accuracy in grading is especially important when the specifications call for “special graded aggregate” because payment for such work is usually based on tons or cubic yards actually placed and includes compensation for all materials, equipment and labor (including fine grading and trimming), and all the other incidental costs needed to complete the work according to the engineer’s opinion. Time taken and materials used are critical to profitability. Today’s instruments can help.
Most contractors say the size of the site to be graded is important. “We have used skid-steer loaders with grading attachments, and it worked perfectly, but not for jobs where the grading was deeper than, say, a foot,” observes an experienced worker for Al Aldinger Construction in Dawson County, MT. “For some of our jobs-and you might not believe this in this day and age-we have finished with grading by hand. Grading the small forecourt for a car dealership was the site for that elementary grading technique. Our machines could not achieve the desired finish.”
The reduction of rework is a benefit that all contractors appreciate. What disappointed the young worker mentioned above (whose company didn’t own a small dozer) was that he found himself spending far more time maneuvering the motor grader than he felt was necessary. Using a machine of the right size and grading with first-time accuracy were mentioned by several contractors as critical aspects of completing a job in good time with no wastage. This was a consideration when John Deere developed its H-Series dozer line (the 450H, 550H, and 650H). “All dozers push dirt,” says David Werning, director of international operations for Deere Construction Equipment in Moline, IL. “If you want one that also has the finesse for finish work, the H-Series is the answer.” These dozers have a center of gravity engineered to provide a balance and stability that will improve grading ability, as well as single-lever steering and direction control for smooth steering and pinpoint maneuverability, even with heavy-blade loads. The three-pitch adjustable blade offers a pitch of 52°, 56°, and 60° (with several lengths of blade also available). Full-power turns, unlimited counterrotation, infinite speed control, and automatic load sensing can all contribute to improved mobility and maneuverability. In a demonstration for our reporters, the double-bevel cutting edge of the Deere 450H penetrated easily and the curvature of the moldboard seemed to shake off even sticky material.