Accurate positioning gives an electric line design and staking company straighter poles and stronger lines.
Mention the American Great Plains and what comes to mind? Wide-open spaces, views that stretch for miles, and lines of electrical poles that seem to run straight into the horizon. But before these poles and wires go up, these lines must first be designed and staked – a process that requires fast, accurate and easy-to-use positioning in remote locations.
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.
Having a straight line of poles is about more than aesthetics, however, it’s also 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,” explains Metzler.
To get that critical straight line of poles, RMA Engineering has started using a correction service from Trimble called CenterPoint RTX.
RTX is a GNSS real-time correction service that takes data from a global network of tracking stations and advanced modeling algorithms to generate precise GNSS positioning. These corrections are broadcast 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 a good match 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, 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 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.
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 Access field software running on a R2 GNSS receiver and a Trimble TSC3 or TSC7 controller.
“RTX and Access (also from Trimble) work really well in the field, the software is 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, 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.”
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. “RTX has made things so fast and efficient,” says Metzler. “On a good day, when everything is clicking, we can easily stake 12 or even 15 miles a day.”
“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.”
Unlike RTK, 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 – often in just minutes – and go.
“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,” says Metzler. “With RTX, when the contractor says they’re ready, our crew needs just a few days to put the stakes in the ground.”
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.”
“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,” adds Metzler. “Most importantly, it ensures that once the poles are planted, we achieve that all-important straight line.”