Robotic total stations, such as the Topcon GPT-9005A shown here, are valuable tools for accurately determining the routes and depths of buried utilities. Photos: Topcon
Using a Topcon FC-200 field controller, Gainesville (Fla.) Regional Utiliies Survey Supervisor Jack Goff enters data that will later be downloaded and output to a land-based map.
That differs greatly from the way as-builts had previously been mapped. In the past, they either estimated locations as best as they could or, if it was a developer's project such as a new subdivision, crews used a hard scanned copy and geo-referenced the location into the system or georeferenced existing CAD data.
“For example, we would enter all the cleanouts, manholes, and valves as per the plan. (Goff) would then come in after having measured all the stations and offsets, and we would apply those to the points we had. However, because we were just going by what the as-built showed, the horizontal locations could be off by 5 feet or more,” McElroy explains. “Sometimes we would come across a situation where a cleanout or a hydrant was put somewhere else entirely. That's no longer a problem. When you are out there shooting it, you know you are right on; you're certain your data is good.”MORE TO COME
Today, more than eight years after that initial push toward GIS began, the system in place at the department is an award-winning (2008 Geospatial Information & Technology Association Excellence Award) model of how to do things right. The database is accessible by nearly all departments within the utility: water/wastewater engineering, water/wastewater construction (both water distribution and wastewater collection), water reclamation facilities, new services, real estate, and strategic planning. A level of shared information is now in place where none existed before.
Despite the progress, says McElroy, there is always more work to be done.
Now that the data is organized and accessible, the department will begin adding technology such as GPS and mobile and server-based applications. “We've made great strides in data value, accuracy, and efficiency,” McElroy explains. “We have some mobile apps that we've recently implemented such as GO! Sync Mapbook from TC Technology, a mobile mapping application that bridges the gap between field paper maps and traditional in-office GIS systems, and we are hoping to get some server-based applications in place as well.”
McElroy says the success they've had utilizing the Topcon equipment in support of the GIS operation has not only streamlined the process, but it has opened his eyes to new possibilities. Currently, after a system is installed in a new construction project, one of the utility's central line locators will meet up with Goff's survey crew and walk along and mark the location of the pipes, manholes, and valves. Goff or one of his crew members will follow, shooting the point with either the robotic total station or RTK system. As accurate as this approach is, this is all happening after the job is complete and the trenches are closed up.
“But there are some utilities out there that actually have their inspectors using RTK,” McElroy says. “When the trenches are open and they are putting in pipe, they are shooting it with RTK. Talk about accuracy: You are literally sitting on the pipe or valve. That allows you to have vertical shots of the valve so that, in the geodatabase, you can specifically attribute it for depth.”
Due largely to lack of funding and resources, the utility has not completed its transition to GIS, but it has progressed. “Based on the success we've had so far, I can see a chance for even bigger things ahead, hopefully within five years or so,” McElroy says.
— Trojak is a freelance writer who works with Topcon Positioning Systems.