Charlotte Douglas International Airport Demanding for Surveyor
If the Charlotte Douglas International Airport (CLT) offered frequent-contractor points, the professional land surveyors at CES Group Engineers would likely be triple-platinum members.
Since late 2015, the engineering and survey company’s crews have been at the facility nearly every day in support of CLT’s roughly $3.1 billion program to renovate its concourses and expand its roadways, curb front, airfield and terminal. Being an integral part of such a high-profile project is testament to how far this company has grown from the modest, residential lot surveys it was providing after launching its surveying services eight years ago.
“We’ve experienced tremendous growth in a notably short amount of time because we fulfill a significant need for professional land surveying services, an expertise that’s been in short supply in this region since the 2008 recession,” says Judy Heleine, owner of CES, based in Denver, N.C., about 25 miles northeast of Charlotte. “Our surveyors and engineers are out in the field nearly every day and they get noticed for the quality work they do. That experience, knowledge, responsiveness, and enabling technology allows us to deliver the required precision on one project and helps seal the deal on the next. It’s a winning formula that has earned us a place on some of the highest-profile projects in the region.”
Being early adopters of advanced survey and geomatics technologies has also enabled CES to expand its breadth of services and pursue substantial contract opportunities with more confidence.
“We invest heavily in varied technology that allows our licensed land surveyors and field crews to tackle any surveying job out there,” says Kent Hudson, PLS and CES’ geomatics division manager. “Each new piece of equipment builds our expertise, which helps us deliver specified results on time and on budget, heightening our profile and enabling us to secure immense projects like CLT.”
Indeed, equipped with a pool of modern survey instruments and newly acquired scanning technology, CES survey crews have been providing first-class data to help engineers build CLT’s final destination.
CLT is the 10th busiest passenger airport in the United States, ranking it higher than some of the country’s biggest names: Orlando, Miami and Houston. In one decade, it flew from the 18th busiest airport to the 11th in 2016, landing in the top ten last year by welcoming 46.4 million domestic travelers and 3.2 million international passengers through its 114 gates and five concourses. Such growth has been putting CLT on a collision course with overcapacity.
With all indicators showing increased passenger demands, airport executives developed “Destination CLT,” a master blueprint that defines the construction and renovations it needs to ensure it has the capacity to handle future growth through 2035.
Given CES’ proven performance on previous design and construction surveying projects at the airport, and its knowledge of the facility, multiple CLT prime consultants and contractors chose the company to serve as the primary survey provider for more than 24 individual projects.
Since construction work began in 2015, CES survey crews have been on the ground floor of the majority of the anchor projects designated in Destination CLT, including the $200 million expansion of Concourse A, the first completed project in the initiative, which added nine gates, constructed a new ramp and taxi lanes for the new gates, and modernized its amenities.
Assisted by their Trimble S7 robotic total stations, Trimble DiNi Digital Levels and TSC3 and TSC7 data collectors, CES field teams have been providing all aspects of construction staking.
“For all of these projects, we’ve had to ensure that all of our horizontal and vertical points are accurate to within 0.01 of a foot,” says Hudson. “That’s not easy to consistently maintain when you have such a chaotic, machine-heavy and sometimes cramped work site. But despite the challenging and unexpected conditions, we’ve been able to stay on spec every day.”
And since the summer of 2018, they have been able to extend the breadth and detail of their data through the addition of Trimble’s SX10, a scanning total station that combines surveying, imaging, and scanning. That functionality has proved particularly useful for two other massive airport projects: the Elevated Roadway (EVR) and the South-Crossfield Taxiway (SCT).
“The SX10 has become instrumental on CLT projects,” says Hudson. “It’s not only giving us the flexibility, speed, mobility, precision, and safety we need, it’s reinventing some of our historically traditional survey approaches and creating new business opportunities.”
An extensive, four-year undertaking, CLT’s EVR project is widening the existing four-lane terminal approach road to 16 lanes to create more badly needed space for vehicle drop offs and pickups. Five new upper lanes of the EVR and four temporary passenger walkways were opened in April 2019, marking the completion of Phase 2 of the $50 million initiative. The final stage of the project is scheduled to finish in the fall of 2019.
Initial construction began in November 2015 and CES crews were on site from day one. Every day for three years, field teams were using their survey equipment for installing control points, and staking out curbs, piers, girders, columns, as-builts, and bridge bents, which are structural elements used to support girders. They also used their technology to locate existing storm and sewer infrastructure and stake out new construction points for rerouting and replacing those systems.
“We had extremely tight tolerances to ensure all the pre-fabricated steel beams fit correctly and were at the correct height and horizontal plane dictated by the design,” says Hudson. “All of our measurements had to be exact.”
In the latter stage of Phase 2, CES was asked to perform as-built surveys of the support columns for the elevated roadways and bridge ramps. As they had just acquired an SX10, the timing proved opportune.
CES had been doing column as-builts with their traditional equipment and it was painstaking. To capture the circular columns, crews needed to measure the circumference, shoot multiple points around the column, bring that data back to the office and then calculate the “best-fit circle” to indicate the column center. Using the scanning function of the SX10 allowed them to capture the entire column at once.
“In addition to the time-consuming process, traditional techniques require a prism, which can introduce some error because of its thickness,” says Hudson. “So you have to perform many calculations and checks to ensure you’re precise. With scanning, you get the actual surface so it’s easy to pinpoint the column center.”
With the SX10 available, a field team opted to scan seven remaining bridge columns–the instrument’s debut project at CLT.
After re-establishing site control–given the confined, active work site, they had to verify control every day–the two-person crew set the scanning total station on a control point and scanned the first column 100 ft away. They performed that routine three more times, and in less than three hours, they captured 3D, 360-degree views of each of the seven columns at an accuracy of 0.01 ft. They saved the data on their TSC7 controller using Trimble Access field software, which combines optical, scanning, and GNSS data, plus images in the same job.
“Scanning eliminated the need for setting traditional targets and provided a safer working environment for our crew,” says Hudson. “And we captured substantially more data–millions of data points–in half the time it takes with the conventional methods.”
Back in the office, Hudson input the point cloud into Trimble Business Center (TBC) software for processing and quality control. He then exported the 3D data into AutoCAD to produce a final drawing showing the column centerline locations. Per the client’s request, they delivered the drawing as a PDF.
Based on the success of their first experience with the instrument, it wasn’t long before Hudson tapped it to resolve another challenge at CLT.
A Good Surprise
In January 2019, one of the primary design-consultants on CLT needed survey support for CLT’s ambitious South-Crossfield Taxiway (SCT) project, a new 4,000-foot-long taxiway, along with a bridge, that will connect the central and east side of the airfield.
CES had worked with the consultant company on previous projects for the City of Charlotte, in which they produced cost-effective, high-quality deliverables on time. Based on that success, the company selected CES for the SCT project.
CES’ field crews were tasked to create a topographic survey of the entire site, which consists of dense, wooded areas; low vegetation areas; flat, open taxiways and runways; and elevated retaining walls and ramps. As part of that survey, they needed to locate and map critical utilities, taxiways, runways and ramps. Such a varied landscape required multiple technologies and approaches.
However, because this site is located within CLT’s airfield, CES was required to perform their work overnight to avoid disrupting airport operations and to ensure their safety and the safety of airport staff and airline personnel.
They set control using a number of Trimble R8s GNSS receivers, occupying each control point multiple times and then calculating the averaged coordinates for each point. They then ran a closed traverse loop using the S7 for horizontal control and the DiNi level for vertical control to within 0.01 ft. With control established, three different survey crews used multiple S7 total stations and TSC7 data collectors to collect all the field data including ground shots, utilities and critical tie-in points.
There was one particular area, however, that gave Hudson pause: a 40-acre, concrete cargo area. This “flat” apron is comprised of 107, 20 ft x 20 ft concrete slabs laid in a grid pattern. CES was required to locate and pinpoint every concrete joint, or seam, within this vast area, along with any grade change over the cargo space and taxiways.
“To acquire that kind of survey over 40 acres would have required us to take 5,000-7,000 shots using our total stations,” says Hudson. “We’d have to set a rod every 20 feet, take a shot, and move to the next point 20 feet away. Although our technology would deliver on the precision, I calculated that it would take eight nights of work to complete it. Having seen the speed, range and accuracy of the SX10, I thought it might be a better alternative.” He thought right.
Arriving on site at 11p.m., he and his colleague used the previously established primary control network and set additional “spur” control points as needed. Setting the scanning total station on a chosen control point, Hudson captured the scene, collecting not only the concrete joints and surface-elevation variations, but also the tops and bottoms of retaining walls, storm grates and building corners at distances up to 300 feet from the instrument. In 10 scanning set ups, the crew captured the entire 40 acres in a single seven-hour shift.
“I didn’t think I’d use the scanning functionality on a huge, flat surface so I wasn’t sure how it would perform, particularly in low light,” says Hudson. “I went to the site expecting it would be a three-night job, and I was shocked that we got it all in one night. Our dealer, Duncan Parnell, had assured me that darkness wouldn’t be a problem, and they were right. I not only acquired millions of 3D points that clearly show all the concrete seams and subtle grade variations, I captured substantially more data in nearly 13 percent of the time.”
An additional efficiency benefit came from the “big picture” screen of the TSC7 and the integrated survey workflow provided through Trimble Access, which enabled crews to seamlessly manage the data from myriad project tasks and sync data between field and office in real time.
“The large controller screen makes it really easy to see in any environment like bright sun, overcast, in the middle of the night, and even wearing polarized sunglasses,” says Hudson. “That allows us to quickly set up new jobs and move between jobs. And with Trimble Access we can transfer data between the office and field in real time and check emails so it’s like having your office with you.”
Back in the office, Hudson processed the point cloud using TBC software and its automated extraction tools to remove any extraneous features such as parked airplanes. After cleaning the data, he created a 3D topographic model of the 40-acre concrete apron and exported it into AutoCAD to produce a final 3D surface. Two days after capturing the data, CES delivered the topographic survey to their client.
Since finishing that survey, CES teams have been back on the SCT site with their S7 total stations to collect the locations of all the sewer and storm systems across the 300 acres. Work on the SCT project will continue through 2022.
With the company involved in 16 active projects at the airport, Hudson cannot readily predict when the SX10 scanning functionality will be used again–they use it every day as a total station–but he says it’s only a matter of time.
“Since purchasing the SX10, I’m using it in on projects I never thought I would, like scanning features at busy road intersections and large-diameter water main projects,” says Hudson. “Its versatility, the ability to scan and survey in one instrument, its ease of use, and its speed save us so much time in the field. And on such massive projects like CLT, we need that. It does not sit idle.”
Between Destination CLT and other on-going projects, CES won’t be sitting idle, either–it just opened its third office in Columbia, S.C. With a docket that looks as full as CLT’s departure board, those phantom frequent-contractor points probably wouldn’t get used anyway.