Keeping Bosnia Connected: Tackling Cell Tower Inspections with Laser Scanning
In the last two years, the GBM Group has embarked on a growing opportunity to use 3D laser scanning to advance and optimize cell tower inspections across Bosnia and Herzegovina, allowing customers to better manage and monitor tower structural integrity.
The GBM Group d.o.o., a firm based in Sarajevo, Bosnia and Herzegovina, is making a name for itself in the region thanks to its willingness to look beyond conventional practices.
Founded by professional surveyor Benjamin Mešić in 2019 as a technology focused engineering and surveying firm specializing in the infrastructure, the young firm of just 13 continues to take ever larger and more complex projects.
Slavica Matić, chief technology officer and geodetic engineer at the GBM Group, believes the company’s rapid success is due to its problem solving mentality and investment in advanced technology. “We try to work on projects that are different; we like a challenge,” she explained.
Case in point, in 2021, the firm became one of only two companies in the country to own a laser scanning solution, the Trimble® X7 3D laser scanner along with Trimble RealWorks™ office software and Trimble Perspective® software for post-processing.
“We received the scanner and the post-processing software one day and the next day we put it to work,” said Matić.
The firm initially purchased the technology to support historic preservation activities. Matić explained, “Early on, the 3D laser scanning opened the door to document, study, understand and monitor any element or site of our cultural world heritage sites. We also scanned and modeled some old fortresses, a few buildings and also created a 3D model of a concrete structure to support project renovation.”
Over the last year, the range of applications has expanded to tunnels and, most recently, cell tower laser scanning to support tower maintenance and inspections—a first for the customer. A recent cell tower mapping project for Bosnia’s largest communication company clearly demonstrated the power and purpose of this laser scanning investment.
Towers of opportunity
In the first phase of the project, the GBM Group was tasked with inspecting about 70 cell tower structures spread across the country that are largely difficult to reach. Most of the structures are located on a hill or deep in the woods that can’t be easily accessed with traditional survey equipment.
“When we won the project, the client wanted to know how we would gather the data and exactly what level of detail they would have,” Matić said. “They were excited about the possibilities but not all that sure about the results because scanning is not common in Bosnia.”
To begin each tower scanning, the survey team placed control to assure point clouds were positioned in a specified coordinate system. “While the scanner is working, we measure the control points with a Trimble R10 GNSS Rover. The entire data-gathering process takes about 30 minutes to set up and gather the data,” she added.
While Bosnia is a small country, it still takes considerable time to drive to each of the towers. She continued, “One day, my colleague drove 1,000 km just to scan 5-6 towers, so equipment portability and ease of use is important to us.”
Beyond the speed of scanning, Matić said that she and her team also appreciate the scanner’s self-leveling feature, which automatically compensates for survey-grade leveling, and the Trimble Registration Assist for automatic registration.
The advantage of the data obtained by scanning is that large amounts of rich imaging and scan data can be collected quickly and efficiently. Even data which is not directly required for the project at hand is obtained and can be retrieved down the line without another trip to the site.
“The ability to check registration in the field is very helpful as we’re moving from tower to tower,” Matić explained. “By using Trimble Perspective in the field, we can instantly see if something doesn’t look right. In fact, with this system, almost everything can be done in the field. We only have to do a few checks in the office and the data is ready to go.”
Once the scans are post processed, GBM Group sends the customer the point clouds in a standard file format along with the coordinate system details. With the data, the client has the ability to perform condition assessments of the tower structure and adjacent assets to aid their plans for maintenance and improvements.
Laser scanning technology offered a range of benefits for customers. It enabled the identification of potential problems and the inspection of the tower's structural integrity. Laser scanning imagery can reflect damage and deformations that may not be visible to the naked eye and monitor them over time. Further, the data has allowed for the monitoring of deviations in the tower's construction from its original design plans.
GBM Group believes laser scanning will continue to be an integral part of the firm’s expanding services in 2023. Time and cost associated with tower inspection has been reduced. The data also provided the customer the ability to inspect difficult-to-reach or hazardous areas, as well as locations with limited visibility. Furthermore, laser scanning enabled safer, more accurate, and more efficient data collection for structural inspection of towers. Lastly, it reduced human error and allowed customers to have a better overview of the data.
Matić concluded, “The client was very pleased with the cell tower datasets that we provided from the laser scanning platform. They immediately hired us to perform the next phase of the cell tower project—evidence that our methods are not only effective, but essential. In the second phase of the project, about 60 towers were scanned.”
• Trimble X7 3D laser scanner
• Trimble RealWorks office software
• Trimble Perspective software
• Trimble R10 GNSS system