Motor grader, Dozer And GPS Boost Site Work Efficiency

By Gini and Dan McKain | September 28, 2010

Tiger Contracting is using GPS technology on a new motor grader and a new dozer to complete site work on a 178,000-square-foot Lowes Home Improvement Center project in Indian Harbour Beach, Fla. The project also involved demolition and recycling of concrete on the site.

"Productivity is the name of the game on this project," noted project manager Scott Smith, adding that the company added a new LeeBoy 685B motor grader and a Cat D5G dozer to assist with the site work on the 15-acre site. Both machines were outfitted with Trimble Model GCS900 GPS machine control systems. The Trimble system uses the MS980 smart antenna — an integrated GPS receiver and antenna — mounted to each end of the machine blade, and can operate in a stakeless environment to an accuracy of 20 millimeters to 30 millimeters (0.1 foot).

"Technology, power and maneuverability are the factors that make it happen for us on this job," Smith said.

Tiger subcontracted the job from Marcobay Construction, Inc., also from Lakeland. The work has a tight time line. It's made even more challenging because the new center is being built on the site of nine buildings damaged or destroyed during a recent hurricane.

"At the same time we are preparing the site," adds Smith, "we were crushing, processing and recycling a significant amount of old onsite concrete material." This included old footers, building pads and paving.

Demolition of the existing structures was handled by Cross Environmental. Tiger then brought in a portable crusher and screener to process the salvaged concrete into #57 stone, fines and #4 aggregate, and to recover the steel. The #4 material was used in the construction of an on-site storm vault. The #57 stone was used as bedding and backfill for underground utility lines. The extra #57 stone and the fines were incorporated into the construction of the building pad.

Smith noted that "equipment utilization and mobility" were two major considerations on this project. According to site superintendent Rick Mosley, the LeeBoy motor grader was specifically selected for its ability to cope with tight working areas. Normally fitted with a 10-foot sliding moldboard, it was instead fitted with a longer 12-foot blade because it was felt that the 15,200-pound machine with its 110-horsepower Cummins diesel engine could handle the weight of the on-site sand and processed stone.

Even though the site sounds large, he adds, its layout complicated construction.

"That's where GPS and laser technology come in," Smith said, adding that "15 acres sounds like a large area. However, by the time we have much of the sitework done and the building laid out it shrinks considerably in size. The subcontractors, demolition contractor, the block layers, the underground utility contractor, and the paving contractor all have their materials and equipment here too. So the site shrinks significantly," he continued.

During parking area construction, which has involved a large amount of earthwork, Tiger has relied heavily on the GPS and laser technology.

The extension of an existing large retention pond also utilized the new Leeboy 685B motor grader and the Cat dozer and their high-tech electronics. To reprofile and enlarge the existing stormwater retention pond and reprofile the drainage pattern, the contractor used a Komatsu PC200 excavator to outload the stockpiled material into a Case rear dump hauler. The Cat dozer and the LeeBoy motor grader, using the Trimble GPS system, then spread the fill, which was compacted by a Bomag roller. Because of the extremely dry weather, Tiger crews used two water trucks almost constantly to rehydrate the soil.

Underground utilities, including a live 8-inch sewer line, further complicated work. Most of the old lines had to be removed before new lines could be installed.

Yet another aspect of the project was the addition of a 12-foot wide turn lane to U.S. Route A1A to feed the Lowes complex. Tiger Contracting used the LeeBoy to profile the subgrade and add two 6-inch thick lifts of crushed limerock and to work in and around several power poles that had yet to be relocated. The 12-foot moldboard was just right for the new 12-foot wide lane and maneuvered easily around the obstructions. The Bomag roller handled compaction.

With the summer rains and start of the 2007 hurricane looming ever nearer, Tiger Contracting had its work cut out for it. But heavy equipment and high-tech electronics helped it all to come through on time.

"The faster we get the job done, the sooner they can open the store for business and we can go on to our next project," Smith said.