Inspection case study

Building with Confidence: Using AR to Ensure Precision in Prefabricated Construction

Prefabrication is on the rise, with an increasing number of projects requiring the construction of components offsite before delivery onsite. While prefabrication can speed up construction schedules, it may also lead to a higher potential for human error and delays.

CONSTRUCTION SAVINGS

REWORK SAVINGS

$31K

Excavation, repositioning, redesign and additional labour cost

OTHER SAVINGS

12 DAYS

Labour of adjusting, repositioning and correcting the error

THE PROJECT

Size:
95,000 m2

Cost:
$500
million

Stage:
Underground Services (MV)

Industry:
Mission Critical

Project:
Data Center

Errors during the installation of prefabricated concrete chambers can result in serious consequences, causing delays, requiring rework, and having a knock-on effect on subsequent trades.

In this case study, XYZ Reality’s Engineering Grade AR™ headset, the Atom™ and Field Engineer discovered the delivered chamber onsite was different from the design outlined in the Technical Submittal provided to the field, with incorrect layouts and shapes, causing misalignment with what was required, resulting in significant rework and delays for the subcontractor responsible for installation.

Building with Confidence: Using AR to Ensure Precision in Prefabricated Construction

Design deviation: Using AR to rectify position of prefabricated element

The project owner in relationship with the main contractor selected XYZ’s Engineering Grade AR solution to be deployed on a hyperscale data center project in the Netherlands to ensure the highest levels of project accuracy onsite, visibility of real time works, and access to crucial data, with the end goal of eliminating errors to deliver this critical infrastructure on time and on budget.

During the installation of prefabricated concrete chambers, an XYZ Field Application Engineer (FAE) was tasked with deploying Engineering Grade AR to

inspect the chambers. Upon inspection, the Atom identified a number of major issues. It was clear that the prefab chambers supplied by an external manufacturer did not match up with the intended design.The received chambers had various deviations from design – the size, the inlet layouts, the shape, and in some cases all of these at the same time. Unfortunately, this error was not flagged or identified by project teams until the XYZ arrived onsite, at which point three of the concrete chambers had already been installed incorrectly.

In this instance, if XYZ solution had been deployed earlier, the concrete chambers would not have been installed incorrectly and the problem could have been resolved well before critical works had begun.

Interestingly, prior to receiving the chambers onsite, there were multiple design changes between the owner, project team, manufacture and subcontractor. These changes were not communicated and followed up correctly – as a result, XYZ highlighted the issue to the subcontractor, and this led to them reforming their processes going forward.

Field Application Engineer - Akos, XYZ Reality:

“The subcontractors were thrilled to have the Atom on the job site. They were always delighted to see the team and eventually comprehended the situation. After arriving onsite and showcasing the technology and its impact, everyone wanted us to be there for pre-and post-installation. The level of trust between XYZ, the project teams and the subcontractors was something I have never seen over the course of my career in construction.”

Design deviation

The original design of the chamber was cube-shaped, however what was commissioned and delivered onsite had an additional overhanging plate fixed on the bottom. This additional feature caused issues because there were multiple underground services near the installation and it impacted a nearby surface water drain. The manufacturer had added this unplanned element for an unknown reason, causing delays in the installation of the pipe. The team had to remove the overhanging piece and ensure that the structure was still sound before they could proceed, which was a significant amount of additional work that was unplanned and unbudgeted for.

Another impact was the issue with the duct inlets. The initial design for the outlets had already been completed, but they had to be altered due to the change in the inlets. This meant that they also had to revise their designs for the ducts and their crossings between the two chambers, as their previously determined positions had to be adjusted.

The knock-on effect

On this occasion, the chamber deviation was affecting the very same subcontractor, as follow up works were also with them. The subcontractor had to replan and update their resources because the chamber deviated so radically from the design.

As a result, the subcontractor began remedial works to rectify the issue. The chamber required additional insulation work, which led to it being open for almost two months. Luckily, follow-up trades which included connecting the ducts and installing cables were not delayed.

Why is it important to build it right, first time?

Had the chamber been designed and manufactured correctly, it would have been a straightforward task to lift it into place, backfill, and continue without any issues. However, due to the mistake, and it not being caught in time, it caused significant problems and resulted in a major dispute between the owner, their project teams and the manufacturer, their design team, and their quality team. Despite the challenges, the outcome was positive as it led to significant improvements in the company's internal processes.

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