For RMA Engineering LLC, a Kansas-based company specializing in the design and staking of electrical lines for rural electric cooperatives, the goal of every project is the same: straight lines.
“At the end of the job, we want the poles so straight that when you line up and look down the row, all you see is the first pole,” says J.P. Metzler, PE, a civil engineer with RMA Engineering.
The firm uses Trimble’s CenterPoint RTX correction service to get lines arrow straight, he explains. However, when it comes to field staking for electrical lines, straight lines are about more than aesthetics. They are critical to the structural stability of the entire utility system.
“The straighter the poles, the stronger the line will be, which makes the whole system more resistant to strong winds or ice and snow deposits,” says Metzler.
Well-Suited for Field Staking
The American Great Plains is known for its wide-open spaces, views that can stretch for miles, and lines of electrical poles that seem to run straight into the horizon. But before these poles and wires go up, the lines must first be designed and staked — a process that demands fast, accurate and easy-to-use positioning in remote locations.
Trimble RTX, a GNSS real-time correction service, uses data from a global network of tracking stations and advanced modeling algorithms to generate precise GNSS positioning. Corrections are broadcasted to the roving GNSS receiver via a set of geostationary satellites or over the internet, which the receiver uses to produce GNSS positions accurate to less than two centimeters.
It is this use of satellites that makes the system particularly well suited for RMA’s work in rural areas because it removes the need to source local corrections or set up a GNSS base station.
“We do a lot of work for rural electric cooperatives in the western great plains states,” says Jake Schur, staking supervisor at RMA Engineering. “When working in wide-open spaces like these, Trimble RTX is all we use.”
The company is currently working on a FEMA powerline rebuild project in western Oklahoma. The three-year project involves roughly 3,000 miles of staking. Crews are using four Trimble GNSS receivers to obtain such things as the horizontal position measurements needed to space the poles correctly and to check elevations so they can choose the right-sized pole.
According to Metzler, using the wrong-sized pole could cause the conductor to pull the pole out of the ground or put enough pressure on the cross arm to cause it to break.
“This vertical measurement doesn’t require survey-grade elevation,” he says. “We just need a relative elevation based off our last pole so we can adjust the location or size of the pole.”
By knowing their current positioning accuracy in both the horizontal and vertical components, crews always know they are setting the stakes in the proper location and with the required level of accuracy.
“Knowing the stakes will be within one inch of center assures that we can offset a right of way line or monument and that we are in the easement we need to be in,” adds Schur.
Field Staking for Electrical Lines and Designing on the Fly
Whether working in Oklahoma, Nebraska, Kansas, or Texas, RMA does its preliminary line design using the electric cooperative’s software. To physically stake a project in the field, the RMA crew uses Trimble Access field software running on a Trimble R2 GNSS receiver and a Trimble TSC3 or TSC7 controller.
“Trimble RTX and Access works really well in the field, it’s very accurate and, because it lets us design on the fly, saves us a lot of time,” says Schur. “That’s why we routinely work with a co-op’s staking department to help them leverage these solutions to offer a better, more streamlined resolution for their staking.”
Once the poles are staked, Trimble Access generates a shapefile that is exported back to the cooperative’s software, where the preliminary design can be adjusted to match the actual field-staked project. The file can also be easily shared with property owners, who often have questions about, for example, a pole adjustment.
“We can send the file to them, let them look at it right in Google Earth, and get their blessing before we go ahead with the construction,” says Metzler. “This gives us the ability to make sure all stakeholders are happy — it just makes jobs that much easier.”
The Need for Speed in Field Staking
Before the advent of GNSS, RMA’s staking procedures required up to three crew members: one with a total station, one at the end of the line with a range rod and another walking along the line setting the stakes. With the GNSS system, RMA can now do the job with just one person.
“On a good day, when everything is clicking, we can easily stake 12 or even 15 miles a day,” says Metzler. “When we’re working jobs that require the staking of thousands of miles of line, such as what we’re doing in Oklahoma, just imagine the time it would take if we had to lay out RTK base stations.”
Unlike RTK, Trimble CenterPoint RTX doesn’t require transporting and setting up a base station — a step that can add significant time and logistical issues to a day’s work. Instead, a crew can simply get to the site, turn on their GNSS receiver, initialize, and go.
“The amount of time RTX is saving us in the field is simply tremendous,” adds Schur. “Although it depends on terrain conditions, I would venture to say we save at least seven man hours per mile compared to using a conventional transit and measuring wheel.”
As a bonus, when flying to a job site, RMA only needs to transport a single GNSS rover and controller — a factor that helps minimize costs and logistics.
“The system is so intuitive and easy to learn that our crew really enjoys using it,” says Schur. “That’s why we use it almost daily on the Oklahoma project and will continue to use it for every co-op job we do.”
Metzler adds, “The bottom line is the Trimble RTX correction service helps us keep our prices low and do our job faster and with greater quality control. Most importantly, it ensures that once the poles are planted, we achieve that all-important straight line.”