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As the benefits of a comprehensive GIS effort have become more and more apparent, larger cities and municipal utilities have been steadily getting on board with the technology, citing it as something of a "no-brainer" in terms of better asset availability, increased accuracy, ease of access to information, and so on. Smaller towns and cities, however, have been reluctant to make the same move, often citing it as both too daunting and far too cost-prohibitive. The City of Troutdale (OR) Department of Public Works (DPW) proved an exception to that rule, embracing the GIS concept early on. But an in-house challenge, a good deal of research, and a subsequent bold technology move (via a contract for a scan of the area using an IP-S2 3D Mobile Mapping System from Topcon Positioning Systems) took that effort to the next level. Today, they not only have one of the state’s most comprehensive geodatabases and a 3D file from which department assets and other objects can be identified, measured and logged, they’ve also risen to regional public works notoriety as "The Little Town That Could." Bravo Troutdale.
Y.E.S. to GIS
As mentioned, the City of Troutdale (population 16,000) has been a fairly staunch GIS proponent for some time now. According to Travis Hultin, the DPW’s Chief Engineer, the move in that direction started roughly 16 years ago with a conversion of the department’s CAD maps.
"I was actually just starting here," he says, "but I remember that, even though the department had an active mapping program through CAD, they saw the writing on the wall, knew that things were headed toward GIS and started taking steps to get us there. That first involved poring over drawings and extracting the necessary data to form the attribute tables behind the maps. That alone took a couple of years. From there we started migrating the maps over to the ESRI environment, building the attribute tables, and so on. It was quite an undertaking."
That initial effort covered basic public works assets such as pipes and manholes. However, largely because of the value GIS provides, it’s been gradually expanding ever since. The difference between the outdated CAD technology and GIS was, quite literally, like night and day, says Hultin.
"With the old system, we basically had a huge CAD map on the wall," he says. "If it was for the sanitary sewer system it would have had all the pipes and manholes shown on it . Each item would have had a little number next to it that referenced a huge notebook which contained all the info we were trying to maintain for those features. So, to get the info we needed, we had to go through that book, find that number and get our data. With GIS we could just click on it and everything we need would immediately be at our fingertips."
Getting to that point took a concerted effort on everyone’s part, with the yeoman’s share handled by Christine Amedzake, the department’s GIS Analyst. Small in stature but fierce in her commitment to the technology, Amedzake has taken GIS at Troutdale to enviable lengths. Today that includes a geodatabase with 120+ layers, many of which are made available to the full department, other city departments, even the general public via its website.
"While we do have that many layers in the system, I believe we have 60 to 65 feature sets that I myself use on a regular basis. We have them broken down into groups: one is `Political,’ with boundaries, property lines, taxes, etc.; another is `Environmental’ and pertains to water bodies such as rivers, streams, creeks, watersheds, and wetlands; still another is `Infrastructure,’ and so on. And each one of these groups is broken out into different subgroups. So, for example, under `Infrastructure’ we have the storm system, a sanitary sewer, the water system and streets. Inside of those sets are additional subgroups: inside storm, for example, we have storm manhole, storm pipe, storm catch basins–essentially anything that is storm-related has its own feature."
The value GIS brings to the department is evident almost every day as users–both in-house and otherwise–quickly and easily access data. For department users, it is, obviously a valuable inventory tool. However, Hultin says it goes much farther than that.
"Much of the value GIS brings is in its ability to track history," he says. "Take fire hydrants for example. There are some in the City that are very old and have never been replaced. When we begin a round of hydrant replacements, we could use GIS to scour the data and tell us what we need to replace based on specific criteria such as the number of ports. Then it would tell us their location, type of hydrant, when they were installed, and so on–it is an extremely powerful asset management tool."
As an engineer, Hultin says it also allows him and his colleagues to find out everything they need to know about an existing piece of infrastructure related to a project without actually going out into the field, or, as is often the case, digging something up to find it. "In the past, proceeding on a job meant pulling out maps, file folders and old reports just to get basic information. That’s all been streamlined."
The Next Step
As the City’s GIS matured, a potential problem with horizontal accuracies was identified. Old maps, for example, were showing a water line going through a customer’s yard when in fact it was under the street. It is suspected that the issue was largely the result of either the way the maps were originally built in CAD, or things that happened during the migration from one software to another, or both. Knowing that something had to be done, Public Works Director Charlie Warren came to his group with a challenge.
"I’ve been in Public Works for 35 years now and will be the first to admit that I am very `old school,’" he says. "When I was a young engineering tech, we would go out to an intersection with a pocket tape and we would measure the location for, say, a water gate valve from the curb, and get that location to within 1/10 of a foot. So I challenged our group to have our mapping system reach that level of precision. Truth be told, I was prepared for us to go out and manually verify every single gate valve in the city."
Around that same time, Hultin had just seen a presentation by the PPI Group, the local Topcon dealer, showing Topcon’s IP-S2 Mobile Mapping System and–with Warren’s challenge in mind–suggested that Amedzake should catch the presentation as well. She took his suggestion to heart.
"I went to Portland in the morning and saw an hour-long presentation in which we were shown someone who had contracted to have a mobile mapping session done, and explained how it had helped them. The PPI Group gave a great overview of the technology, how it works, how accurate and reliable the data can be, and so on. But all I could think about at the time was, regardless of how valuable it could be to us, we simply didn’t have the budget to purchase anything like that. When I realized you could purchase the service rather than the equipment, I thought we might stand a chance at it as a possible solution to Charlie’s challenge."
Making Their Case
Amedzake says she followed up that visit with calls to Richard Hill, PPI Group’s specialist in laser scanning sales and support, asking more questions, then invited him to come in and give the full DPW a personal presentation. Despite claims of what the IP-S2 could do,
Charlie Warren says he was apprehensive.
"I’ve been trained that, in order to trust a measurement, someone has to have physically been out there and measured something; to trust a machine to measure it to that degree of precision took a lot for me," he says. "However, when Richard opened a file and started snapping from one feature to another, checking and rechecking it, and showing that he could consistently come up with the measurement values, I knew this was the right way to go."
To bolster their case for funding the effort, Amedzake prepared a report comparing costs for achieving that same 1/10 foot survey grade accuracy city-wide. In it, she spotlighted four separate scenarios which showed costs ranging from a low of $7,500 for the scan and subsequent work, to more than $300,000 to have crew members manually tape-measure or GPS the city. The time needed to do so was also called out, showing a range from a mere eight hours to do the mobile mapping, to two to three years for other techniques. Realizing that, as a rule, numbers do not lie, the board approved funds for the effort, PPI Group was contacted and the City of Troutdale was ready to have its picture taken.
Going for a Ride
Christine Amedzake leaves little to chance and, as a result, did a good deal of research prior to having the city driven and mapped. Not only did she identify the best driving routes, she literally went out and drove them before having the scan done.
"That was important for us because this was a rental and it was on a per-day basis," says Hultin. "So if we couldn’t get the city done in one day, we would essentially double our costs. Doing what she did, Christine saved both time and money for the department. Based on her preparation, she made estimates as to how long it should take and was within 20 minutes of those estimates."
The actual mapping process itself was fairly simple: the day began with Hill, Amedzake and a senior Public Works field operator setting up a base station– in this case, a Topcon GR-3–followed by a static alignment of the IP-S2. Once rolling, three LiDAR scanners mounted on the PPI Group’s vehicle scanned and generated a high-res 3D point cloud of everything encountered–both on the road surface and within a 30 meter range around it. In addition, a 360° digital camera shot six pictures every three meters which were then stitched together in post-processing to produce a spherical street level-type photo. In the roof-mounted IP-S2 unit itself, a number of sensors determine the vehicle’s position and attitude (in real-time), while a dual-frequency GNSS receiver tracks both GPS and GLONASS signals for optimum coverage. Wheel encoders, retrofitted to the vehicle’s rear wheel axles, detect the rotation of its respective wheel. By comparing the difference in rotational speeds between the two wheels, accuracy is even further enhanced.
Putting it to Work
Though the actual physical scan was completed in one day, Amedzake will be processing the data using Topcon IP-S2 data processing software and, using ArcMap, integrating it into the system for some time to come. Even in light of that, Warren says the time savings and additional benefits derived from the scanning process were dramatic.
"I don’t want to give the impression that, after two days, it is all in the computer and we are instantly able to see where every single gate valve is. We still have to sit down and import it, ID it and so on. But we are now doing that with one GIS Analyst sitting at a desk as opposed to teams going out into the field. And, most importantly, we know the numbers are dead on."
To see what can be done with the data Troutdale DPW has collected and Amedzake has finessed is to see a geospatial work of art. Subdivisions can be singled out, property lines similar to a plat map can be turned on, entire counties or portions therein can be highlighted. And the available data is mind-numbing.
"Keeping in mind the groups I mentioned earlier, it’s easy to see how this helps us," says Amedzake. "If I click on `Water,’ it will show me all the water meters, hydrants, blow off valves, as well as the line itself. This line, for example, is 492′ long and is made of 12" ductile iron pipe. If I highlight a specific area, I get additional info such as where it is located, when it was built, what subdivision it is part of, where the as-builts are located, hyperlinks to the as-built drawings, the number of hydrants, number of blow-off valves and when it was last updated to GIS. It’s easy to see how 60 layers can grow to 120 in no time."
Troutdale DPW maintains a number of GIS-driven interactive maps on its website and has found that they are highly-valued by engineers, developers, contractors, etc. But Warren says there’s little denying the impact scanning has had upon the DPW itself.
"It’s hard for me to even begin to list all the value this technology will bring us and some of the other departments," he says. "Whether we are dealing with utility systems, zoning codes or any number of other things, it all comes back to that spatial info. Being able to link an issue to a certain property, go right to that property in the database, get the data we need on it, see the precisely located infrastructure that is passing in front of that property, and so on, is incredibly valuable."
Hultin adds that scanning the city not only captured locations for all the things they already had in their old maps, it became even more valuable by giving them a lot of things that they didn’t.
"Now, we can easily bring that data into our GIS to create a new set of features that we hadn’t specifically mapped before–things like trees, curbs, utility poles, and so on. Other people and other departments can get similar benefits. And, because scanning captures everything, we can continue extracting additional mapping elements from this for the foreseeable future. It’s really the dataset that keeps on giving."
Amedzake sees yet another, more esoteric benefit from the scan. "Ten years from now, we can look back at this as a very detailed snapshot of a single day in the summer of 2011. We can compare it to new scans or to aerial photos and see what’s changed. We didn’t think anything like this was feasible for a city of our size, but we showed that it can be. I’ll never forget what a great feeling it was to be presenting our scanning and GIS experience to a consortium of Portland area GIS people and companies, holding out an external hard drive and saying: `Here’s our city.’ That was very cool."
Larry Trojak is a communications writer for his own firm, Trojak Communications, in the town of Ham Lake Minnesota. He is a frequent contributor to construction and survey magazines.
A 1.793Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE