Being prepared directly applies to asphalt paving contractors, especially those intending to get maximum benefit from 3D paving and milling technology.
"Half the job of paving with 3D technology is done with proper preparation," says Jeroen Snoeck, paving segment manager for Trimble. "If the subsurface below the paver matches the design, the 3D paving operation is able to minimize asphalt usage and achieve the best smoothness.
"You need to get the site design right before setting up the 3D infrastructure and control points," he continues. "The machine will pave within millimeters of the design. Therefore, you don't want mistakes in the design which would be shown in the results."
Tight tolerances, time frames
Yates Construction Company of Stokesdale, N.C., completed a massive project with a stringent requirement of maintaining a 1% cross slope for surface drainage in the final laydown of the asphalt. Typical highway paving projects require a more forgiving 2% slope from centerline to shoulder.
The project was to construct the new Jacksonville Port Authority's Port TraPak Container Terminal at Dames Point in Jacksonville, Florida. Yates placed 254,000 tons of hot asphalt over a 125-acre container/trucking terminal in 9 1/2 months.
To accomplish the required surface tolerances within this tight time window, Yates equipped its Roadtec RP 185-10R paver with a Trimble PCS400 Paving Control System. This enabled asphalt to be placed on a sub-grade with a final grade within +/- 1/100th to slope specifications. International Underground Corp. of Jacksonville, Fla., completed earthwork using a motor grader equipped with a Trimble GCS900 Grade Control System with GPS and laser augmentation.
"It's extremely hard to hold that tight of tolerance accuracy on a paving project," states Paul Sowa, project engineer with Yates Construction. "Most contractors won't warranty a project that's under 2%. And on this project, we had some areas (around the drainage grates) where we had to maintain a .58% and .63% slope. But by using the GPS with the laser augmentation system on the grader and the paving control system during paving, we were able to deliver those tight specifications."
Stakeless process saves time and money
In Virginia, E.V. Williams of Norfolk was the principal contractor for the I-64 / Battlefield Boulevard Project in Chesapeake, a complex interchange rehab that included widening a heavily traveled two-mile stretch of interstate from six to 10 lanes and widening a cross-over bridge from one to three lanes in each direction. It also included adding five newly constructed bridges and new braided exit and on ramps.
"Our use of GPS grade control technology was major," says Kyle Myers, GPS manager, E.V. Williams. "It's unbelievable how much time and money it saves you when you go from at least a four-man crew, an operator and two workers pulling the string and one checking grade, to one guy on a machine, no stakes... Plus, the GPS system allowed us to work at all hours if needed. We were able to construct one area of our project, the eastbound extension, completely at night, using only a GPS grader. You couldn't have shot grades in the dark.
"It just made life extremely easy," he continues. "Here's another example: We had one of the on-ramp loops completed from virgin ground all the way to the point of blue-top stakes. There was one dozer operator."
After paving was completed, the Virginia DOT commented, "The readability is unmatched. When you come down the highway and hit that new section, it's completely silent in your vehicle; there are hardly any bumps. The sub-base is dead on."
The Ohio State University Airport in Athens, Ohio, is ranked one of the top five busiest airports in Ohio. The airfield's traffic comes from corporate and private traffic, as well as the University's own Department of Aviation.