Extending the Boundaries
In the past, in order to perform a topographic survey, surveyors would set up a baseline, cut out grid lines and run direct levels across the ground to determine vertical locations, while pulling a tape in order to establish horizontal location on the grid. When this was completed, the data notes were taken to the office and the locations were plotted by hand and interpolated to derive the contour positions. Most often, the office work was done by a computations technician who had never been to the site to see the actual conditions the numerical values represented.
The introduction of compact electronic total stations in the early 1980s, as well as data collection and computers in the latter part of the decade, has brought on the race for equipment manufacturers to produce a “field to finish” survey system. Though these "field to finish" systems eliminate many steps, the lack of true coordination between equipment manufacturers and software developers forced surveyors to operate with equipment and software applications that performed some functions well while doing a poor job with other equally important functions.
The traditional practice of having field crew chiefs perform the field locations and survey technicians perform the office computations perpetuated a communications gap in translating field information into the final product for clients. This gap in communication was created by a number of factors, mainly a lack of ample sketches or minimal sketch details which cause the computations technician in the office to incorrectly interpret the sketch. Another common problem lay in not obtaining sufficient locations to define a critical aspect of the job or in simply recording bad angles or bad distances in the collector.
These communication deficiencies are all associated with the amount and location of the data collected in the field and are not recognized until the data is reduced and the office technician attempts to put the project together. Return trips to the field to correct errors in data or to compensate for the lack of sufficient information can be very costly to the project budget and can affect both the quality of the map and the project schedule.
The Freedom to Move AroundSurveyors have been searching for a digital technology that would allow them to see what they are locating at the same time they perform the fieldwork. Such a system has been available through the use of laptop computers in the field. However, in order for this system to work, the computer must be connected directly to the instrument. The drawback with this technique is that the crew chief who normally is keeping the field book and running the rod cannot see the locations as he or she completes them.
Therefore, what Concord Engineering & Surveying Inc. (CESI, Concord, N.C.) desired was the capability to control a robotic instrument remotely from the computer and to be able to walk that computer anywhere on the project, independent and separate from the instrument. This would enable the crew chief to walk around the site and look at features on the ground and in the CAD drawing as the features were being located. We asked Tommy Dudley of Earl Dudley & Associates, a survey equipment supply company from Birmingham, Ala., and Charlotte, N.C., if he could develop such a system. Dudley, along with representatives of Carlson Software (Maysville, Ken.), collaborated in an effort to realize this application.
"CESI had a vision of how to solve the bottleneck of office communication and we were happy to help," Dudley says. "Our main goal was to get the CAD technician to the field and out to the pole, thus running a crew as a one-man set-up. We convinced Carlson representatives to work closely with the CESI team to get over the hump and give us all exactly what we wanted."
With much teamwork, deliberation, and trial and error, a radio link was established between a Leica TCA 1103 Robotic instrument (Leica Geosystems, Norcross, Ga.) and a mobile laptop operating Carlson Software. This innovation allowed our crew chief, Cecil Porter, to freely walk around the site and control the instrument via a laptop mounted on the pole or strapped to the waist. This enabled Porter to determine the features to locate and immediately see the results displayed on the laptop. The results of our six months of experiments with this system have been excellent. By viewing the data on the computer screen as it is being collected, Porter was allowed—for the first time ever—the freedom to survey a site and see the drawing developed without the burden of operating the instrument using the traditional "hands-on" method.
"Because this is so new, there is a learning curve in terms of programming the software to meet specific project needs," Porter says. "With that being said, it won't be long before I can perform various types of surveys without the help of anyone or anything except this equipment and computer. It's going to work out really good."
Thus far, Porter's most successful project in utilizing this system was a topographic survey for design improvements to the intersection of NC 73 and International Drive in Concord, N.C. NC 73 is a heavily traveled corridor and an important link between two exploding communities in Cabarrus and Mecklenburg counties in North Carolina. Viewed by local business and government leaders as a vital artery in the Charlotte metro region, citizens and commuters alike have insisted that NC 73 become a priority for improvement.
At the eastern end of NC 73, Concord and Kannapolis in Cabarrus county are experiencing residential, commercial and industrial annual growth rates of nearly 10 percent. The hot areas around Lake Norman in north Mecklenburg County are experiencing a similar boom in residential and service industry growth. Lake Norman is one of the most popular recreation spots in North Carolina, with boating, fishing, water sport, and golf activities that are driving a luxury home real estate market that is going like a rocket on rails. In addition, each end of NC 73 intersects an interstate highway--I-77 in Mecklenburg county on the west end and I-85 in Cabarrus county on the east end. All of these factors have contributed to heavy congestion on NC 73 and have increased the need for facility improvement, especially at the intersection of NC 73 and International Drive. International Drive serves the International Business Park at Concord, a 517-acre mixed use business park. This master planned project is the areas premier location for the development of retail, office and industry. As the business park continues to expand, the intersection at NC 73 and International Drive has become increasingly congested and hazardous.
“When growth corridors saturate the existing infrastructure beyond capacity due to high residential and commercial growth patterns, the system collapses,” said Michael P. Schneider, vice president of The Nolim Group out of Boca Raton, Fl, developers of the International Business Park. “When this happens, future opportunities for economic development becomes limited. Thus, it is vital that the community-at-large anticipate infrastructure needs at the present to sustain balanced growth for the future." Schneider adds, "At The International Business Park, NC 73 and International Drive are our lifeline to the Interstate system. Thus, we must enhance these important roadways in order for the park to mature to its maximum potential. "
The ProjectOur client, the city of Concord, challenged us with data collection in this highly congested area with a fast track schedule. This project involved many different items for field crews to locate and survey. Crews needed to create a digital terrain model of the existing pavement and of the areas to be widened, as well as make property ties, and locate gravity and non-gravity utilities.
Our primary tasks were to complete the project in the allotted time, to not interfere with traffic and to acquire the information in a safe yet efficient manner. Our challenge, as with many surveys, was to effectively and correctly record the required information under strict time constraints, thus avoiding the need to backtrack and gather missed or incomplete data.
We were able to load the limits of the survey on the laptop so the crew chief could see when the targeted area was covered. As the pavement was located, it was also drawn and displayed on the laptop in real time for the crew chief to see. Breaklines, utilities, ground shots and physical features were all located and appeared on the laptop for the crew chief to check for positioning and accuracy of data. When the crew chief was done with locations, he was able to use Carlson survey to process the T-net and check the contours to see if they appeared correct or if he needed to obtain more locations to define a more detailed area. Using this technique, the fieldwork went smoothly and quickly.
Though the fieldwork took about the same amount of time as with any robotic equipment, the difference was that the crew was able to use robotic data collection techniques in a manner that allowed them—while away from the instrument—to actually “see” what they were surveying in real time as they located features in the field. The most significant time savings came in the office with the reduction of computation time and the elimination of costly return trips to collect data. In other words, the data came in from field essentially already “processed.” Therefore, the only office step left to complete the product was to import the drawing and finalize the digital terrain model. This step involved correcting a few lines, setting up layers in the drawing file, and adding a border and title block. In using this new system to survey a site, the office computations time was cut in half, thus offering both time and money saving to the client. As the surveying industry becomes more familiar with this equipment and continues to perfect the layering system for the laptop, the time and costs saved should increase to even higher percentages.