For prefabrication to be successful, accurate information about the destination of the final installation is a must. 3D laser scanning makes that possible.
Digitalization has had a profound impact on the Architecture, Engineering and Construction (AEC) industry. Today, traditional processes that were redundant or less efficient are making way for modern tools that support quicker, safer, and cost-efficient construction. One such tool is 3D laser scanning, which enables engineers and contractors to cut costs and speed up designing and building of a project. A report by Global Market Insights suggests that the 3D scanning market was worth $4 billion in 2020 and is likely to grow at a CAGR (compound annual growth rate) of over 10% from 2021 to 2027. The increasing need for capturing a high volume 3D data for analysis and modeling in the AEC industry will be driving this trend.
3D laser scanning in construction
3D laser scanning is used in the field to capture detailed data about the construction site. This data is known as point clouds, which basically are connected database points in a 3D coordinate system. 3D laser scanning allows construction professionals to perform as-built surveys, identifying mistakes early in the design phase to prevent expensive rework. It also helps in improving the building plan, design, construction, management, and renovation.
Further, 3D laser scanning also helps in making the Building Information Modeling (BIM) process more efficient. When 3D scanning systems are used in place of traditional hand measuring methods, there is great enhancement in speed, efficiency, and accuracy. “Geospatial data captured using laser scans, drones, and combined with BIM technologies are increasingly instrumental in mitigating risk, and ensuring certainty of outcome in construction projects,” says Amr Raafat, Vice President of VDC & Technology, Windover Construction.
Emergence of prefabrication
Prefabrication means creating a building’s components offsite, generally in a factory, and then assembling the building on site. It is claimed that the world’s oldest known engineered trackway, the Sweet Track, constructed in England around 3800 BC, employed prefabricated timber sections. In the 19th century in Australia, many prefabricated houses were imported from the United Kingdom. In the 20th century, the method was widely used to build temporary housing for thousands of urban families in the United Kingdom that were bombed out during World War II.
Vice President of VDC & Technology Windover Construction
Even though prefabrication in itself is ancient, recent advances in technology have boosted adoption, and have made it possible to prefabricate an entire multi-storey building in very little time. A modular or prefabricated structure produces about 70-90% less waste than a traditional building. Also, offsite construction ensures quality and safety, and the building materials are protected from weather and natural calamities during the construction process.
For prefabrication to be successful, accurate information about the destination of the final installation is a must. This is where 3D laser scanning comes in handy as it allows engineers to access 3D scanned data before the fabrication stage to make initial assessments and fundamental calculations of a site’s build-out. Gaining exact measurements for offsite preparations and manufacturing can result in massive savings in time and labor. “We have been implementing geospatial data into our prefabrication workflows to ensure that offsite construction elements built in the factory miles away from the actual site fit perfectly in the installation space. As laser scans allow us to communicate in real time and with excellent accuracy, managing factory made prefabricated elements on site becomes easy,” explains Raafat.
BIM/VDC Technologies Manager Reis Contracting
A prefabrication factory is generally located far from the assembly site, sometimes in another country. Any deviation in a prefabricated component while manufacturing may cause an assembly failure, leading to rework or reconstruction that can increase project duration, cost, and even risk. Therefore, conducting physical trial assembly (PTA) is necessary before transporting prefabricated components to large-scale assembly projects. PTA ensures a precise, flexible and fast display of cut-outs, formwork parts, and mounting elements — accurate calibration, referencing, positioning, and inspection of precast components.
3D laser scanning can quickly and accurately capture the 3D shape of physical objects. Using laser scanning in PTA makes quality check methods faster and more efficient.
“Laser scanning in prefabricated construction is essential in ensuring proper fitment and placement of prefabricated elements in any space. LiDAR can provide current, accurate data up to 1/16, depending on the hardware used to capture data. There may be a little more overhead involved in this process. Still, better the overhead you can budget for than the change orders you can’t if, for some reason, existing or proposed drawings, reports, hand measurements, or assumptions are incorrect. Be right the first time and always scan first,” says Christopher Allen, BIM/VDC Technologies Manager, Reis Contracting.
Even when a project design is perfect, human errors are quite possible. 3D scanning proves its value throughout new construction projects using prefabrication techniques by finding human errors before building on one another. By verifying the site with a 3D laser scanner, stakeholders can spot and correct these mistakes. Going forward, 3D laser scanning will also become part of the estimating process — one of the most critical components of the prefabrication method. Scanning would provide valuable details to estimators trying to project timelines, understand the site’s context, and evaluate labor and material costs.