Accurate survey control is a fundamental aspect of high-rise construction. From established control points on the ground to maintaining vertical operation as the building rises, survey control not only ensures the structural integrity of the building but also keeps the project on schedule and within budget.
However, as buildings continue to grow taller, traditional survey control methods struggle to keep pace with these demands. Techniques such as vertical lasers and plumb bobs that were once reliable may no longer guarantee accuracy at altitudes where building sway can become an issue.
Could GPS technology provide the answer?
A team from Baker Concrete Construction decided to find out.
A Breakthrough in Survey Control
Tom Trotter, line and grade manager for Baker Concrete Construction, was initially skeptical. While GPS is well accepted in heavy civil construction, where it is used to guide and control heavy machinery for dirt work as well as measure features on a project site to monitor progress and maintain quality control, it’s not seen as often in building construction, especially for building control.
“For this approach to be successful, it would need to be able to maintain accuracy for multiple stories,” Trotter said.
Trotter and his team began testing a GPS core wall survey system created by Leica Geosystems. Developed after years of research, the system has been used in some of the most significant construction projects around the world.
Leica’s Core Wall Survey Control System for High-Rise Vertical Alignment: A Concrete Contractor’s Review
The Leica core wall system involves the placement of GPS receivers on the building exterior as active control points that move up as floors are completed. A key advantage of the core wall system is its ability to reduce construction time, which is essential in large-scale construction projects.
“The core wall system is also highly adaptable,” Trotter said. “Your control is where you want it. You can move the GPS rovers to where you need them, depending on the jobsite conditions.”
Accurate Results Every Time
Initially, the team constantly cross-checked with their existing layout. They used control mounted around the jobsite for layout on the first few floors, then set up the GPS rovers and check their layout. “After doing this for a few floors, we saw that nothing ever changed,” Trotter said. “The layout was the same. The Leica core wall system consistently delivered highly precise data every day; it quickly won me over.”
The team began implementing the Leica core wall system on major projects. Laying out control points and control lines for the MEP trades was accurate. Their sleeves and penetrations stacked and posed no issues. “The core wall system made the process effortless,” Trotter said. “The general contractor had their own surveyors come in to verify our control, but we never encountered any discrepancies or problems with others inspecting our work. The Leica core wall system proved reliable, delivering accurate results every time.”
In addition to accuracy, the team also experienced time and cost savings by avoiding return trips to the ground level every time new control was needed at the top of the building. “The speed and accuracy of the system are unparalleled,” Trotter said.
“The implementation of Leica’s core wall system has significantly impacted our approach to constructing high-rise buildings. It helps us keep up with the pace and demands of the job. With the Leica system, we are able to streamline our procedures and increase efficiency.”
— Tom Trotter, Baker Concrete Construction
Comparing Methods
Accuracy
Traditional methods like vertical laser and plumb bob require significant manual oversight, increasing the chance for error as building height increases. The Leica core wall system addresses this by fusing advanced GPS technology and automation, eliminating reliance on manual measurement under challenging conditions.
Efficiency
Conventional methods require substantial manpower and time. By contrast, the Leica system reduces the need for multiple staff and complex logistics, enhancing productivity and allowing quick redeployment of resources.
Cost Savings
While initial setup costs for advanced systems may be high, the reduction in labor and time spent rectifying errors leads to substantial long-term savings. Real-world applications demonstrate the cost benefits.
The Future of High Rise Survey Control
Looking ahead, the integration of advanced technologies like the Leica core wall system signifies a shift towards innovation in survey control. Trotter, who reported on his experience with the core wall system in a presentation at the Hexagon LIVE technology conference, said the Leica core wall survey control system quickly paid for itself and is now the company’s standard for high-rise structures.
“The implementation of Leica’s core wall system has significantly impacted our approach to constructing high-rise buildings,” he said. “It helps us keep up with the pace and demands of the job. With the Leica core wall system, we are able to streamline our procedures and increase efficiency. This is a positive outcome for both our company and our clients.”
To explore how the Leica core wall survey control system can revolutionize your next project, contact us.
