Feature: Machines, Models, and Mobile Data
Professional Surveyor Magazine - November 2012
Three case studies highlight the time and cost savings of machine control, intelligent milling, 3D site modeling, and multi-site connectivity.
By PSM Staff
Winds of Change
3D site plans and models combined with fine grading control facilitate success in construction of a major wind-turbine assembly plant.
How do you construct something really big, meet a demanding timeline, and do so to exacting specifications? “State-of-the-art solutions” is buzz-terminology that might come to mind. In the case of the new Siemens wind-turbine assembly plant recently completed in Hutchinson, Kansas, two state-of-the-art solutions in particular were key to the project’s success: 3D site plans and grade control systems.
Part of the back-story is the boom in wind generation, which has seen a twentyfold increase since 1999 (2,400 to 48,000 megawatts), making the United States the largest wind-producing country in the world. The demand for towers and their components does not abate. Get up close to one of these thousands of huge towers (upwards of 300-feet high), and their sheer immenseness is revealed. Perched atop each tower is a huge nacelle containing the drive train, gearbox, and generator, all weighing in at more than 88 tons. You better have a big plant to assemble nacelles, with a beefed-up floor to handle the weight.
The new 277,000-square-foot Siemens plant built on a 108-acre site was designed for such weight and capacity considerations. “The amount of concrete will exceed one million square feet, so we need to make certain the grade is accurate,” says Martin Howard, field engineer with Bob Bergkamp Construction of Wichita, Kansas. Bergkamp was awarded the contract for site prep work by Gray Construction, a nationally ranked design-build firm selected by Siemens for the design and construction of their new facility. “The plan called for a 12-inch base of fly-ash, so you can see this is designed for extreme weight,” adds Howard.
“This is a design-build project so we needed to quickly adapt as changes were made and the project evolved,” states Howard, who explained that, upon receiving the site plan from the civil engineer for the project, “I built a complete digital model using Trimble software, and we used that to guide our motor grader to achieve consistent grade throughout the project.”
Bergkamp Construction had numerous grading concerns for the project. The site contract included constructing the building pad, the 1.2-million-square-foot storage areas (including a large outdoor lot), the employee parking lot, three detention ponds, and service roads leading to and from the facility.
“Every subcontractor on site that had anything to do with layout, dirt, concrete, or asphalt—even down to the surveyors and Gray Construction, the Siemen’s design-build firm—was using my information, my model, which is actually a first,” states Howard. “I’ve never been this in-depth with a project.” Howard used several software programs to add layers to the Trimble core software programs.
“Our first task was to construct the building pad,” states Howard. “We used a couple of the six-wheeled scrapers on the site to create the footprint and then used a motor grader equipped with Trimble GCS900 Grade Control Systems with dual GPS.” The system put the site plan—design surfaces, grades, and alignments—right inside the cab and helped the operator achieve the plus or minus a tenth-of-an-inch accuracy that was required.
Grading for the nacelle inventory/holding lot was critical. “The tolerances for our dirt work were a quarter inch, which is usually, as you know, a paver’s tolerance,” states Howard. “The concrete company had originally selected a different dirt contractor, but they were so impressed with the quality of our results from the dual GPS system on a couple of side spots we did for them that they switched to us for everything.”
Bergkamp Construction recognized that the subgrade was very critical because having any soft spots would create major issues. “If there were soft spots in the subgrade, that 11 inches of concrete would to start to crack and crumble and tear apart. It could create future maintenance costs—patch this, patch that. So that’s why our grading had to pass so many tests … density tests, moisture tests, and others.”
The project was completed ahead of schedule. “We’ve put a lot into this project and became the ‘go-to’ source for answering questions and preventing problems because of the quality of the 3D model we built and the tight-finish grade we achieved on all three areas of the site,” Howard concludes. “Granted, there were a lot of changes on this project, but that’s the nature of design-build sites. We’ve invested a lot of sweat and time into this project, but with the help of these [technologies] we were able to save production time and achieve the results we wanted.”
Connecting Multiple Sites
Two-way data transfer capabilities reduce travel time, improve design responsiveness, and make a company competitive.
In Wisconsin and the upper Midwest, Edgerton Contractors is known as a leader in earthwork and environmental contracting services. From heavy highway construction projects with the Wisconsin Department of Transportation to environmental site remediation to road building for wind farm development, Edgerton Contractors has an exceptional track record for meeting clients’ design and build requirements with a focus on efficiency and sustainability.
Edgerton Contractors is currently working on three large projects located several hours apart. In Milwaukee, they are working on an interstate reconstruction project that includes the removal and re-grading of several miles of pavement as well as the construction of multiple tunnels, retaining walls, and bridges. In the Madison area, the team is working on a large site development that includes all grading work for a new business campus. Northwest of Milwaukee, Edgerton crews are grading access roads and excavating footings for a large wind farm project. The challenge of working on multiple large projects simultaneously, spread over a large geographic area, is new for Edgerton.
“We currently have multiple complex projects we’re managing that are three hours apart, and each project involves many, many design changes and daily as-built documentation,” said Jeremy Craven, vice president of engineering for Edgerton Contractors. “As we were planning these projects, we could see that the logistics of getting design revisions to the field and as-built documentation to the office was going to be a huge challenge.”
With this dispersed project load, the Edgerton Contractor’s team needed to adjust the way they manage, share, and analyze information. The ongoing trend among the major surveying and construction equipment manufacturers is to also provide complete field-to-finish software solutions, with emphasis on connectivity and process and data management. Edgerton sought a completely integrated solution from a solution provider to affect changes sought for their operations.
In this example, Edgerton turned their existing Trimble data collectors (8-TSC2s and 2-TSC3s), which already gather and share survey data, into connectivity “hubs.” To do this the company adopted what is called the “Connected Community” from Trimble (TCC). Connected Community is a service that enables construction businesses to manage and share information via their own unique website, connecting the office to the field.
By hosting an organization’s information for connected sites centrally, the Connected Community is able to connect people, devices, and systems. This has reduced the effort and cost required to keep the Edgerton team current with two-way data transfer capabilities that ensure that the most current project files are in the hands of engineers and project managers in near real time. So, instead of driving several hours each day to save and share project files, users are able to download and upload important project files in any area where wireless communication is available.
Directly from the job site, crewmembers use either a Wi-Fi card or the integrated GSM/GPRS modem within their TSC3 controllers to securely log in to Connected Community. This allows the site controller software to facilitate the flow of real-time information between field and office. One-touch syncing capabilities allow Edgerton crew to select their syncing preferences, so individuals are kept up to date.
As a first step to adopting TCC, Edgerton established a consistent protocol for updating files and syncing information. Today, generally once each day, users sync their data collectors to add new files, update design changes, share survey and site photos, review change orders, and make new work orders.
“Overall, our complete information workflow has been transformed with [this completely integrated solution],” said Craven. “There’s no question that it saves us a ton of time. We experience a return on our investment in a few ways: first, the entire data transfer process is performed electronically with the push of a few buttons—this is obviously faster than driving the information to and from the office. Second, we are beginning to see how the integration of TCC with [Trimble’s data-management software] Business Center‑HCE will ultimately result in a smooth, simple workflow—well suited for staying on top of large volumes of as-built data and design revisions. Finally, the speedy delivery of design revisions to the field reduces delays and rework.”
Craven estimates the web-based system has helped Edgerton shave off dozens of hours of driving time each week, and as a result they’ve saved thousands of dollars in fuel costs. In addition, 10 to 15 hours each month once spent focused on lower-level data transfer and processing tasks can now be spent on activities that directly contribute to the bottom line. Team members can now focus more of their time on creating effective design solutions, servicing existing clients, and bidding on new projects.
Today, Edgerton crews can also make smarter decisions that reflect current conditions on the project site. For example, crews can change the location of a temporary alignment to avoid unforeseen obstructions or make an adjustment to an excavation depth due to changes in the water table for quicker and more informed decision-making that pays dividends.
Smooth Move Yields Bonus
When a contractor implements “intelligent milling” on a scenic highway project, the project earns a “smoothness bonus.”
Century Drive Highway in Oregon was anything but smooth driving, let alone cycling: it’s tough to enjoy some of the most breathtaking scenery in the region while hanging on for dear life on a narrow winding highway, competing for pavement with trucks, four-wheelers, and tourists headed for the mountain resorts.
The Federal Highway Administration put out a bid to have 10.5 miles of the forest highway resurfaced as well as widened and realigned in some areas. The finished paved width of the highway is 32 feet, with five-foot wide paved shoulders added to accommodate bicycles. The bid led some to dub the project as the $7 million bike path, although it was actually a case of increased traffic on an aging two-lane road that inspired the project.
Winning the bid and serving as general contractor, Tidewater Contractors of Brookings, Oregon was responsible for this two-season project. The company has been in business since 1978 and has a focus on highway construction with adjunct ready mix and asphalt paving operations.
Tidewater Contractors’ first step was to check the existing survey control network on the national forest road project. These are the ground surface points that were used for survey staking and grade control. “We used a Trimble SPS930 universal total station to verify the points and confirm the quantities,” states Mark Mann, project engineer with Tidewater Contractors. “This is all necessary prep work for creating an accurate 3D road model.”
The original ground model and staking note data in digital format was provided by the Federal Highway Authority. Mann combined this with his own data collection at the site to create the 3D model. “I began by building a 3D road model for the project that we use for both survey stakeout and grade checking—something I do with all road projects,” Mann says.
Additionally, Tidewater examined the scope of the work to be performed and saw beneficial opportunities for machine control. The company developed a “value engineering proposal” for the project to include the use of 3D machine control. The proposal, which was accepted by the FHWA, specified that Tidewater and the government would share in cost savings due to the reduced survey staking reaped by the technology.
“We didn’t tear up any pavement at first because it required that we replace it with temporary asphalt, so we spent the first season installing culverts, building walls … most of the work outside the existing pavement,” says Mann. In addition to facing a short construction season, the work was also being completed during the high recreational period when the road use is at its heaviest.
With a traditional 2D control system, the machine mills to a constant depth and essentially copies the old surface. With the “intelligent milling” grade control system on the cold planer, the milling depth is adjusted according to the 3D design to match the design profile with +/-5mm accuracy.
“We saved a considerable amount of time and additional work by using the [grade control system] on the milling machine” in conjunction with the total station, Mann states. “It increased our production since we milled only what was needed. And we used less asphalt during paving since there were no low spots or unevenness that required filling in.” Tidewater Contractors was able to mill and finish grade up to 12,000 square yards of road surface at a 3- to 12-inch depth in one day.
“There’s no question in my mind that, had it not been for the use of machine control, this project would not have been completed on time—it would have slipped into a third year, which would have had a substantial cost impact to the government,” Mann concludes. “We estimate that the use of 3D machine control for milling and grading saved us 11 days on the project. We finished the last of the paving and the pavement striping in snow flurries that led into five days of continuous snow,” Mann states. “At the time, the project was behind schedule due to Federal Highway Authority change orders and paving rock issues, but we’re pleased that by using technology, we prevented work carryover into another season.”
As Mark Mann looks back on the project, he points to several accomplishments. “First, we received a smoothness bonus of $127,397, and the Western Federal Lands Highway Division reports that we achieved the smoothest ride since they started using the IRI (International Roughness Index) method for calculating smoothness.
“In our case, we had super-accurate milling and consistent, accurate subgrades, which made it possible to finish with our bonus-winning smooth surface. Tech reps were very responsive, helping us calibrate and test the mill—we didn’t have to touch it again. And finally, we created a road with a smooth ride that’s safe for everyone heading up to the Cascade High Lakes area—which is a great feeling.”
Often technology enables productivity gains, but ultimately the success of any technological implementation is due not to the tool, brand, or digital wizardry but the people and support staff who have the foresight, skills, and drive to ensure full realization. The history of surveying and construction has never been short of innovation and technological advances, making it an imperative for surveyors to continually increase their skills and knowledge.
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