Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/726012
Nars Laikram, manager of commer- cial support and development for Vögele. He says 3D in this context is comprised of two factors: 3D job fi les and 3D paving. "When we say three dimensions, we are refer- ring to depth, width, and direction. That's the 3D. In that case, you have a job fi le that tells you at the x and y location, what the depth should be, and what the width should be." Because of this, the most im- portant factor in 3D paving is the model that is transferred into the machine control system. This model includes a proper survey, with the topography of existing conditions carefully compiled. Any errors in creating the 3D model will lead to errors on the job, as they will be replicated at the time of paving. In other words, the old adage of "garbage in, garbage out" applies doubly here. The site con- trol must be maintained, as con- tractors can't expect the paver to pave accurately if the site control is off in any way. "3D systems communicate with a network of base stations that provide precise positioning data so the machines can work off a virtual design," says Jon Anderson, global sales consultant at Caterpillar Pav- ing. "The machines always have to maintain a line-of-sight to two base stations in order to precisely fi x their position. Some urban envi- ronments can interfere with this, as can rural locations with heavy tree or brush cover. Usually, proper planning can ensure that the base station locations will not be subject to interference." In asphalt paving, you don't necessarily need 3D control to drive the paver. You can get by with 2D machine control and just referenc- ing off of sonics, especially with an averaging beam, and still get relatively smooth results, says Kevin Garcia, paving segment manager for Trimble. This is especially pertinent September 2016 | EquipmentWorld.com 74 highway contractor | continued 3D provides smoothness in exacting situations W hen it comes to smoothness, perhaps nowhere is there more exacting needs than on a racetrack. Scotty's Contracting & Stone of Bowling Green, Kentucky, used 3D paving technology in the site prep and paving for the National Corvette Museum Motorsports Park, also located in Bowling Green. The facility is a test track for Corvettes. Specifi cations required no more than 1/8 inch of deviation around the entire track length, as well as a smooth joint in the center. Scotty's started with Caterpil- lar's 3D AccuGrade on their dozers to get the grading down to 100ths of a foot accuracy, followed by 3D paving to within 1,000ths of a foot accuracy. Joint matching the pavers used in echelon, Scotty's used Caterpillar AP1055D and AP1055E pavers working off of Trimble's system to fi ne-tune the slope. "We never would have fi nished on time without it," says Chris Higgins, en- gineering manager for Scotty's. "The biggest benefi t of 3D paving is it precisely and accurately achieves the design, giving us the smoothest, most consistent surface possible." Scotty's Contracting & Stone used Trimble's 3D system when paving the National Corvette Museum Motorsports Park to meet the exacting specifi cations for smoothness required. A Caterpillar AP1055F using 3D control while paving a section of I-65.