GPS technology is transforming management of earthmoving operations by increasing productivity and compressing time schedules, while cutting production costs. Three contractors who have experience with these systems explain how it changed their earthmoving operations and how the technology generates a return.
In-house staking saves resources
Slusarski Excavating and Paving is a site work contractor. "We do earthwork, underground utility work and asphalt paving, as well as general contracting" says Mary Christie, project manager. The company is currently using Topcon GPS with automated machine controls on a Volvo 726B grader and Topcon GPS on four Caterpillar dozers, as well as a field controller unit.
The Topcon GPS allows Slusarski Excavating and Paving to handle most of their required staking in house. This reduces the time and money spent waiting on outside surveyors. "You save money by reducing the amount of stakes that you need as well as reducing equipment downtime if you lose layout stakes and need to replace them," Christie says.
Outside surveyors are not eliminated. "We still need surveyors to come in and set up survey control points. From there, we localize the project using the field controller, and that localization is what the equipment systems run on," says Christie. Surveyors are also used when a high degree of precision is required, and to occasionally double check work done with the GPS system.
The GPS system can be accurate to within a quarter of an inch. "When doing spot checks for grade, you want to get it as close as possible," says Christie. "If I am doing layout stakes, I'll usually give myself between 1/2 in. to a tenth of a foot. You always have a little variation when using the field controller."
In many applications, a tenth of a foot is close enough. "On the job we just finished, we did the majority of our grade stakes and utility stakes," says Christie. However, an engineering company was brought in to lay out the roughly 2,800 ft. of curb and gutter. "As far as curb and gutter, you have to make sure that the grades are perfect and we didn't think we had the resources available for the time it would have required to do that," says Christie.
Engineering companies are also used during peak demand. "If we get backed up where we can't handle all of the staking that needs to be generated, we definitely do use them," says Christie.
The savings in terms of staking are significant. "The staking costs have definitely gone down now that we've eliminated the grade stakes and have the ability to do the layout staking in house," says Christie. On a $1.5 million project, traditional staking costs could run between $50,000 to $150,000. By reducing this cost, the GPS system quickly pays for itself. "If you did two jobs that were between $1.5 to $2 million, I think it would recoup the cost in staking."
The Topcon GPS system had a major impact on Christie's job duties. "It put more responsibility on me and the other supervisors to be able to manage our time and get everything laid out," she says. "The grading files also require a lot of prep work in the office prior to the information hitting the field and our engineer handles that for all of our projects. Last winter, I handled probably 80% to 85% of the staking and layout. I would be staking all day, and then working on everything else I had to do in the evening. We have looked into hiring someone full time whose main responsibility would be to do all of the layout and staking."
There is a learning curve. "There's a lot of ways to screw things up really fast in the field controller and the equipment setup if you don't know exactly what you are doing," Christie points out. "But we managed to get a good grasp on it and we have been able to utilize it to our best advantage. Looking back, I think both the management and the operators acclimated themselves to the system fairly quickly. As you understand how the system works more and more each day, it cuts down on human error. It does cut down a lot of the re-work."