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January 2009

Laser system makes quick work of distribution center construction

Bobcat T300 with laser-controlled grader attachment

With the Trimble laser system, the grader attachment automatically controls the grading blade and is able to provide the desired grade within plus or minus 0.25 inch.

Equipment doesn’t have to be big to take on big projects. Trace Construction, a concrete contractor based near Indianapolis, Ind., is proof. The company uses compact equipment to do the same jobs typically done by larger equipment. In fact, the smaller equipment, combined with innovative technology, helps Trace Construction complete jobs more efficiently and with less cost than if larger equipment is used.

Trace Construction does concrete work for new distribution centers, big box retail stores, warehouses, hospitals and schools. A typical project for the company is the Cooper Tires distribution center being built in Franklin, Ind. The building will have an 800,000-square-foot concrete floor and 500,000 square feet of concrete around the building in driveways and parking lots. Trace Construction is doing all of the concrete and subgrade work on the job.

Doing more with less

A dirt contractor prepares the site for the building. Normally, that includes preparing the subgrade for concrete, but that is now a job Trace Construction takes on, thanks to the company’s two grader attachments, which are equipped with Trimble® laser systems. The grader attachments are used on Bobcat® T190, T250 and T300 compact track loaders.

In the past, when the dirt contractors did the subgrade work for the concrete floors, dozers were used. Larger equipment is more expensive to own and operate because it uses more fuel and the cost to keep it maintained is higher. “The T300 will do as much work as a large dozer,” says Joe Shetterley, vice president of Trace Construction. “In fact, the T300 is faster than a dozer.”

Not only do the compact track loaders have the pushing force to perform the same work as dozers, the grader attachment equipped with lasers keeps the loaders working productively, without wasting movement.

The amount of stone laid in the subgrade is determined by the structural engineer for the job. For the Cooper Tires distribution center, 4 inches of stone is required. At 800,000 square feet, 20,000 tons of stone are being placed in the subgrade.

Shetterley says that it will take only three days to lay the stone for the Cooper Tires building because the laser system works quickly. “We completed a little over 300,000 square feet on the building subgrade in one day with the compact track loaders and grader attachments with the lasers,” says Shetterley. “In other words, we moved 7,800 tons of stone that day with this equipment.”

How the laser system works

Each of the two grader attachments has a receiver. These receivers communicate via laser with a hand-held target that is set up on a pole. After the compact track loaders make their initial pass distributing stone over the area, the subgrade is checked by hand to see if the desired depth is being achieved. If not, the target is raised or lowered accordingly. As the loaders make additional passes, the laser system automatically raises or lowers the height of the grader blade. The only thing the operator needs to worry about is moving the loader around the jobsite — the laser system does the work of adjusting the grader attachment.

The laser system is so accurate that it can achieve the grade within plus or minus a quarter of an inch. Of course, this is important because the accuracy of the grade impacts how much concrete will be used. When more concrete is used than what was planned for, Trace Construction obviously makes less of a profit. The contractor signs contracts stipulating margins of error, the percentage of waste, for concrete costs. On this project, if Trace Construction were to go more than a half-inch over the desired subgrade on the entire area of the building, 1,500 yards of additional concrete would be needed. Shetterley says that would cost him $12,000. “We bid with a percentage of waste of 1, 2 or 3 percent,” says Shetterley. “That money goes in our pocket because the accuracy of the laser ensures we’re only using as much concrete as we need.”

Bobcat T300 with laser-controlled grader attachment

With the T300 compact track loader and the laser-controlled grader attachment, Trace Construction was able to grade 300,000 square feet of subgrade in one day.

While the laser system saves Trace Construction money on concrete overruns, the contractor has also become more profitable by taking on larger projects. Before the laser system, Trace Construction was not able to take on a job the size of the Cooper Tires building. A string line and the loaders were used to create the subgrade before acquiring the laser system. Working that way, Trace Construction could only do 20,000- to 30,000-square-foot sections, a time- and labor-consuming process. Working with a string line, it took four people to do the work. With the laser system, only two people are needed, and they are both working in the compact track loaders with grader attachments, moving material instead of string lines, which finishes the job quickly.

“We would not have been able to do this big of an area without this system,” says Shetterley. “Now that we have the laser, we can control our own subgrade and take on larger work than we did in the past.”

Controlling the subgrade is important because the base the concrete is set on has an impact on the overall quality of the floor. It’s easier for Trace Construction to stand behind the warranties they give on their concrete floors when they control the subgrade.

Zero tail swing excavators lend a hand

A total of 35,000 yards of concrete will be poured for the floor at the Cooper Tires building. In addition, other concrete work Trace Construction is completing for the distribution center includes column pads and footings. Trace Construction uses Bobcat 331 and 442 compact excavators to help with the other concrete work. Three hundred column pads will be built for this project, and using both excavators at the same time, Trace Construction dug 122 in one day.

The 442 excavator has zero tail swing. This allows the excavator to work right next to a building or object while providing maximum spoil placement.

Zero tail swing is helpful when constructing loading docks. There, the footings step down up to 5 feet below the surface of the building floor. Digging the footings in the loading docks requires Trace Construction to drive the excavators down into these areas. There is not a lot of room to maneuver the excavator, and the zero tail swing allows the machine to work without the house hitting something, preventing damage to the excavator and what is being constructed.

While the excavators are helpful, the star of the Cooper Tires project and other jobs Trace Construction completes is the laser system. Shetterley says that Trace Construction paid for the system within a year of getting it, and with the money the company saves in potential concrete overruns, decreased labor and by using compact equipment — which is more economical to own and operate — it’s easy to see how the laser system pays for itself. By using technology and working efficiently, Trace Construction is operating a productive and profitable business.