Surveying Along the Highway
Howard R. Green Company (Cedar Rapids, Iowa) expected nothing out of the ordinary when the Iowa Department of Transportation (IDOT) selected them in 1997 to perform surveying work on a highway relocation project that ran through the southern portion of the state. The project runs through Ottumwa, Iowa, a small community of less than 25,000 people who share their town with buffalo, unimaginable amounts of poison ivy, rivers, farmland, wooded areas and a variety of wildlife. It also covers two counties-Wapello and Jefferson. The U.S. Highway 34/63 project relocates U.S. Highways 34 and 63 to bypass Ottumwa and surrounding towns instead of going directly through the small city as it does now. U.S. Highway 63 will be relocated to an area with dense tree coverage and hilly terrain. U.S. Highway 34 will follow its same route, but with a few minor changes. U.S. Highway 63 will be made into a four-lane highway. Green was hired to do the land corner work, identify property boundaries and determine boundary lines of individual tracks along the highway corridor.
The first sign of something out of the ordinary was when a small dog bit Keith Vlademar, LS, a surveyor with Green, as he knocked on doors requesting permission to be on the property. "I had never been bit by a dog while surveying, and I guess the dog had never bit anyone before either-but he liked me for some reason," he says. He was also surprised that poison ivy grew everywhere, even up the fences.
Poison ivy posed a threat to surveyors since it seemed to thrive in this area. "Since my co-worker, Evan, was sensitive to poison ivy, I had to clear it from the area where we worked. It grows in all the fence lines and covers every fence post we need to work around," Vlademar says.
And as if poison ivy wasn't enough, there was a small herd of buffalo in Ottumwa. "We were told to stay away from them and leave them alone," said Vlademar. "We only got close enough to take a couple of pictures."
Green previously used GPS to establish control on projects, as well as to locate soil borings, tie corners into the project coordinates system and do topographic surveys of areas outside of photo coverage. "We use GPS because it allows us to establish points for a large area in a relatively short time, as compared with traversing to establish control. The accuracy in establishing control is greater. In staking out soil borings, as well as other surveys, you do not have to have control where you are surveying. The control only has to be close," Vlademar says.
On U.S. Highway 34, Green provided additional topography in areas where aerial photos did not cover. The IDOT set control points along the corridor with GPS as well. Since Wapello County, where part of the project was located, was in the process of implementing a countywide Geographic Information System (GIS), the information Green gathered would be used to obtain ownership information and property line information, although providing that data was not specifically part of Green's contract.
Before beginning, Green did research on previous surveys in the region and obtained corner and section information from the county engineer and other surveying sources. Green discovered that IDOT had found and established corners in the area during the 1950s. They also discovered that the Workers Production Administration (WPA) had done some surveying work in the 1930s.
In Jefferson County, their next step was to probe and dig-hopefully finding a stone or marker of some sort. On the first eight miles of the project, Green surveyors searched for the established corners set by IDOT in the 1950s. In order for Green to re-establish these corners, they used a Trimble 4800 GPS (Trimble Navigation Ltd., Sunnyvale, Calif.), which helped immensely since the crops were still in and surveyors couldn't see through the corn. "It only took two days to traverse to most of the section corners using GPS. It could have taken a month or more without it," Vlademar says.
Perhaps the highlight of this project was finding a bridge spike in the root of a tree set by IDOT in 1952. The spike had 9" of growth over it. "All of the reference trees used by IDOT were gone and the only thing we had to go on at the time was the WPA concrete monument, which was not set-it was just lying on the ground," Vlademar says. "It was in an oak tree, from which the pin locator picked up a very faint reading. After cutting away part of the tree, the spike was finally found."
The last 14 miles were more difficult since some of the corners were gone. Green surveyors used the Trimble 4800 GPS on these miles for tying in section corners and fences. According to Vlademar, it only took 20 percent of the time it would have with conventional traversing. "During the time of year when the farmers' crops are in, and especially when the corn was 10' high, we did not have to worry about how we were going to get around or through the crops. We could go 'over' them and go directly to the corner or set traverse points closer to the corner," he says.
Using the Trimble 4800 GPS to traverse to the section corners and to set additional traverse points allowed the surveyors to drive points in 10 to 15 minutes using a total station. Vlademar continues, "GPS was used to gather 90 percent of the information needed and it probably reduced our traversing and the location of other objects needed for section corner re-establishment and boundary location by 70 percent. It did not reduce the time it took to look for a section corner or analyze the information, but more information was gathered in a shorter time period."
Critical points were shot in from two different locations, meaning the base station occupied two different control points. With this procedure, the difference between the two measurements varied from 0.05' to 0.15', which is well within an acceptable tolerance when compared to a traverse of four or more miles in length. In those areas where additional information may be needed farther away or farther out from the project, the decision to gather that information can be made quickly. "It may take one to two hours with the GPS, as compared with one day or more when done conventionally. But you will have, hopefully, all the information at hand for boundary/section corner analysis and save a trip or two to the field," Vlademar says. He also stresses that with GPS, a surveyor has time to gather additional information that may be useful to the project.
Howard R. Green Company is still plugging away at surveying the area as weather permits and is looking to finish in the next year. And hopefully no more dogs will bite surveyors, the poison ivy will die down and the markers will be easier to find.