Preparation for a paving job goes well beyond simply lining up equipment and materials and readying the site. Understanding the design and specifications, soil type, and utility locations is a major step for contractors, and can make a big difference in the profitability of a job.
For Eric Covington of DECCO Contractors-Paving in Rogers, Arkansas, unexpected utility interferences have been a major challenge. They aren’t things a contractor can plan or budget for when preparing for a paving job.
Covington explains how, when these underground utilities are misallocated on the engineering plan, it can have a far-reaching negative impact.
“We bid work based on hours on the job. We feel like we have a good reference point on how long it’s going to take a crew to perform per foot, whether it be pipe, or by the square yard, or by the ton of asphalt,” he says. “When you’re delayed, that hits your pocket.”
Covington feels the problem is primarily due to inaccuracies in records, or simple placement problems, but then the blame game starts.
Communication
Engineers try to involve the utility folks, Covington says, and review the design to pinpoint what needs to be moved. But, follow-through is where the ball is dropped. “You hear back from the engineers, and they say they’ve had our plans and they know the depths, but we don’t know why they’re not doing it correctly,” Covington says.
He doesn’t blame one particular party for this frustration, and says the issues are most likely due to the rapid growth of population, and commercial growth in the area. He says these factors result in multiple adjustments to plans over just a few years, causing utility locations to get lost in the shuffle.
“Things are moving and growing at such a pace, that the utilities can’t keep up,” he says. “We’ve done some work on highway projects that the design was five years old. In that situation, the elevations might not be exact because a temporary overlay may have been put down or a piece of pipe put in. On a $6 million project we’re doing here in Rogers, they started the design on it five years ago and it’s gone through three design engineers. It’s hard to understand what everybody’s wanting.”
Covington says that factor isn’t the engineer’s fault, as it’s more of an operational and budget issue.
“When things go well, it’s usually something that’s designed pretty quick, is a high priority, and has everybody’s attention,” Covington says. “Questions get answered quickly, and you’re able to move on the project.”
He adds that things move more smoothly when it’s a collaborative effort, and nobody is pointing fingers. ”We can’t go out and dig a bunch of holes and justify it before we bid a job and spend a lot of money out there on something speculative,” he says.
“In the end, it takes having an owner, engineering company, and contractor who can all put things in perspective, look at the long term, and understand that if they can all come together and make an agreement on what needs to happen and make quick decisions, then it’s going to move a lot faster. And everybody’s fair to each other.”
Machine control
Machine control and 3D mapping has been in use far longer in dirt work than paving, so for site preparation, it’s a popular tool. Covington has 3D control on his dozers, but hasn’t yet updated his graders. However, that may change.
His company recently picked a job for a local county road where they will be placing 6 inches of base, and laying asphalt on top.
“The county road that we’re paving is 2.2 miles, so we’re going to look at it with the Leica folks,” Covington says. “We’re thinking of doing a profile of the existing road when the county gets done, and want to build our own file. We’d basically just do a centerline profile of the existing road, and build a 3D design off of that. Then, we’ll probably rent a grader with 3D control for a month.”
He describes working this way as “an adventure” for DECCO. “We’ve built new streets, greenfield streets, with GPS and grade control, but I think it’s going to be interesting to see where this goes.”
For roadway repair and rehabilitation work, site preparation revolves around ‘mill and fill’ work that can also benefit from machine control. However, the benefits of this approach are only half the equation, according to Nars Laikram, manager of commercial support and development for Vögele.
“For mill and fill, you’d rather use the 3D on the mill and let the paver follow what the mill did,” he says. “Whereas, if it’s new construction and you have the job files and need to erect stringline using surveyors, then it’s a big advantage just to use 3D, rather than spending the money to erect the stringline.”
But the same contractor that does the milling doesn’t always do the paving. In that case, there hasn’t been a lot of buy-in from milling contractors on 3D control, according to Kevin Garcia, paving segment manager for Trimble.
“They view it as slowing them down,” he says. “For them, it’s easy to set up and go. Using a 3D system and setting up slows them down because they are at a 90 percent utilization rate industry-wide, and are always busy.”
However, Garcia says vertically integrated contractors, those who do milling and paving, are beginning to use 3D control more.
Even with contractors who do both, such as Covington, the size of the job being performed on a regular basis may dictate the adoption of 3D control on milling machinery.
Covington cites a future job DECCO was awarded for a mill and fill in Siloam Springs, where curb recovery and a 2-inch overlay is to be added.
“That job is ideal for being able to use 3D control, but what we’ll end up doing is using the mill, and then dial in the depth of the curb and feather out to nothing. I think that’s a job where you could use it, being 7,000 square yards and pretty straight milling.”
