Don Talend, Write Results Inc.
Recording the locations, dimensions and physical attributes of all equipment owned by rural U.S. utilities seems difficult. Information tools used to build geographic information systems (GIS) have advanced in recent years, however, making the endeavor plausible.
In 2008, a nationwide mapping initiative backed by the National Rural Telecommunications Cooperative (NRTC) began. NRTC represents the advanced telecommunications and information technology interests of more than 1,400 rural utilities and affiliates in 48 states. It invested in the mapping project to help develop technology that would make rural utility GIS more affordable and usable for utility engineering and asset mapping.
As part of the initiative, Great Falls, Mont.-based GeoNav Group International Inc. developed a high-tech, vehicle-mounted mobile mapping system that provides for more efficient collection of rural utility asset data.
Multiple Technologies Collect Asset Data
Redundant and integrative technologies allow the mobile mapping system to capture enough data via vehicular collection for rural utilities to build sophisticated GIS that can be used in proactive asset management. County governments, public works departments and telephone and gas utilities can monitor assets using spatial data content the system collects. Topcon Positioning Systems’ IP-S2 in the mapping system incorporates three redundant positioning technologies with 360-degree digital imaging and laser scanners.
|GeoNav Group drives the back roads of America with their Topcon IP-S2 mobile system to map rural utility infrastructure. Photos courtesy of GeoNav Group International and the author.|
The system mounts on the back of a vehicle and consists of a dual-frequency, dual-constellation global navigation satellite system (GNSS) receiver that establishes the geospatial position of the vehicle. An inertial measurement unit tracks vehicle attitude (pose), and external wheel encoders capture odometry data from the vehicle. Integration of these technologies creates a 3-D position for the vehicle and provides accurate tracking in challenging or denied GNSS environments. A high-resolution digital camera provides 360-degree images. The system records and time-stamps inputs at 15-nanosecond intervals.
Referencing the vehicle location data, the system can capture data from the assets. The IP-S2 positioning system uses 3-D laser scanners with a 30-meter effective range. Every second, the scanners collect 45,000 x, y and z points to obtain accurate geospatial positions for assets. Traditionally, light-detection and ranging (LiDAR) data have been collected from the air. Because this system collects data from ground level, it provides critical data that cannot be obtained from aerial surveys. A laptop computer inside a truck uses a Web browser to communicate with the IP-S2 via an Ethernet cable. Data collection does not require an Internet connection.
“We can add additional scanners to it, change things out,” said Casey Saxton, GeoNav’s chief technology officer and GIS project manager. “It’s modular, so it allows us to adapt as things change in the industry.”
Growing With Technology
The new mapping system collects data so efficiently that equipping a fleet of trucks with it would make the undertaking easier.
With most traditional data-collection systems, field personnel walk up to a utility pole and capture GPS coordinates with a handheld sub-meter GPS data logger and typically one digital photo.
Joey Grzyb, a GeoNav project manager, recalled the first utility territory he mapped after joining the company in 2008: the Tallahatchie Valley Electric Power Association in Mississippi. A crew of field mappers used handheld GPS units to capture coordinates of utility poles covering the 28,000-customer, 4,300-mile utility in a year using trucks, all-terrain vehicles and walking.
Post-processing the data into a GIS, however, was time-consuming because the components were not integrated, Grzyb said.
Data collection largely dependent on human judgment is subject to errors, which are fixed by costly return trips to the field.
This technology allows many people to look at one point in time, Saxton said. Collecting vast quantities of data with the new system allows previously unforeseen analyses of utility infrastructure such as a joint-use study.
A utility can visit the entire system many times and without transport cost. Advanced technology is a major factor in the mobile mapping system’s success, Saxton said.
“If you took LiDAR and the high-speed camera out of the equation, we would not have developed this strategy for doing this type of remote sensing,” he said.
Data Collection Requires Customization
In spring 2010, GeoNav drove two western U.S. utility territories. Taos, N.M.-based Kit Carson Electrical Cooperative serves more than 29,000 members in Taos, Colfax and Rio Arriba counties. Its overhead lines span more than 2,700 linear miles in northern New Mexico. The Empire Electric Association Inc. serves more than 15,000 industrial and residential customers over 1,869 miles of energized line in a 3,500-square-mile service territory in southwestern Colorado and southeastern Utah.
By June, the teams had driven the entire territory.
|The Topcon IP-S2 uses multiple, redundant technologies to capture rich geospatial data that utilities can use for asset monitoring. Photo courtesy of GeoNav Group International and the author.|
Grzyb said that 90 percent of roads he drives for rural utilities are dirt roads. To identify an electric utility territory, he follows power lines.
“The geography of an area plays a huge role in how many miles we cover in a day,” Grzyb said.
He covered some 60 miles a day while driving Empire. Potter and Grzyb said that Taos, N.M., which became part of the United States in 1846, has narrow streets and was not designed for large volumes of vehicular traffic, so driving it took longer.
For typical rural electric, it would take 18 months to conduct a traditional facilities inventory with six to eight people working every day, five days a week. The company now accomplishes the same thing in fewer than four months with two people in the field. One vehicle allows a rural utility to go from having six or more people in the field mapping 400 power poles a day to having one person driving 40 miles an hour and mapping 800 power poles an hour.
On county roads and U.S. Forest Service roads, another problem is encroachment of vegetation along power lines, Grzyb said.
“A lot of times you otherwise wouldn’t see that there are power lines,” he said. “That’s information that a co-op could definitely benefit from.”
In this situation, a LiDAR point cloud defines a shape that is not identified easily with imagery.
The work in New Mexico and Colorado likely constitutes the greatest amount and most detail of asset data gathered from rural U.S. utility systems.
Before GIS development occurs, two post-processing steps take place. First, LiDAR points are colorized using the images. Next, GPS signals are corrected differentially to provide assets’ geospatial positions to within less than 2.5 inches. After post-processing, the data are integrated within the GIS. Two data integration tasks are digitizing (selecting assets in the LiDAR point cloud for inclusion in a GIS) and recording their attributes.
During the attributing process, technicians recorded the attributes of assets such as power poles and compared them against specifications. The power of LiDAR lies in the measurement capability a point cloud provides. For a utility, this capability is critical because a power line sagging over a highway can overload and cause an expensive outage, or a truck might hit it and result in injury or death.
Utilities’ GIS analysts typically must conduct a more thorough inventory of asset condition than what occurs during the attributing process. Subsequent data collection within a given utility’s territory will occur as growth dictates. Some utilities might require updates at least annually, Grzyb, said, especially those where ice storms, hurricanes, tornados and flooding occur.
Outage Management Benefits
GIS offers electric utilities value in managing assets and outages. Geospatial data aids outage management because it is incorporated into a model that utility staff can use to pinpoint territory parts affected by an outage.
Data accessed by customer service personnel can be shared with operations staff when a GIS is developed. The goal is building a model centrally available to utility personnel. In nonemergencies, using these data to schedule pre-emptive maintenance on power lines also can save money.
A LiDAR (Light Detection and Ranging) point cloud is a particularly rich GIS data component that allows measurement of asset dimensions. Screen capture courtesy of the author. Photo courtesy of GeoNav Group International and the author.
For example, customer service staff can identify peak loads and determine that a particular transformer will be overloaded under a consistent peak load. Not replacing that transformer might cause a line meltdown, and replacement might cost at least $100 per foot of conductor.
At Empire’s headquarters in Cortez, Colo., engineering manager Glen Noble and Alisa Gardiner, a GIS mapping technician, anticipated the impact of a GIS they are upgrading with GeoNav’s data in ESRI’s ArcGIS.
“We just had basically maps of the system without much detail,” Noble said. “We knew where the lines went, and we generally knew where most of the consumers were.
“The lines were probably reasonable, but we didn’t know anything about the poles or the equipment.”
Noble anticipates the new GIS data will assist Empire in periodically replacing poles and conductor line in some sections of the territory.
“Basically, we just replace a section of line as either more consumers move in, the old poles just aren’t keeping up, or it’s time to replace a section of line,” Noble said.
The GIS will allow Empire to take a more methodical approach to identifying assets that need repair or replacement, Gardiner said.
“I will finally have a complete database identifying exactly where the lines and poles are,” she said. “I’ll be able to know what’s on every pole and, in some cases, I’ll be able to see the condition of poles. We’ll know the spacing of poles, and we’ll know if the lines are older.”
Processing the GIS data is a significant undertaking, Gardiner said. She plans to flag assets in need of repair or replacement in the GIS.
“Because you have the ability to configure the database however you want, you can flag whatever you want,” Gardiner said.
Multiple utility departments also can access the files, she said.
Noble said that providing staking crews with access to a staking package with accurate data offers the potential to yield significant productivity benefits. The ability to capture the terrain in the GIS might save the staking crew a trip to a site.
“If they’re talking to consumers about changing their service or hooking up new service, they can look at the site terrain model while they’re on the phone with the consumer, rather than just trying to remember what the area looks like,” Noble said.
A possibility in future outage management is indicating outages on a territory map, Noble said. Such a map would indicate to customer service personnel in real time which territory areas are being serviced by crews.
Talend of Write Results Inc. in West Dundee, Ill., is a print and e-content developer specializing in technology and innovation. Reach him at firstname.lastname@example.org.
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