Earthworks installed in excavator cabs shows the location of the bucket cutting edge relative to the design grade, improving excavation productivity and accuracy.Trimble
Aldridge created a connected, technology-enabled planning, design, fabrication and installation workflow that seamlessly plugs into the larger project's concept-to-construction workflows. This integration helped to win multiple contracts on this campus. Building information modeling (BIM), modular prefabrication and the use of five machines equipped with 3D grade control made up Aldridge’s arsenal.
New grade-control paradigm
“Before this project, we did not have even the GNSS survey equipment,” says Jeff Buckley, director of PreFab/BIM at Aldridge. “So we went into this project full-boat, we bought survey equipment and outfitted excavators with it.”
Aldridge initially purchased two Trimble Earthworks Grade Control Platforms for excavators. Soon after, the company added three more Earthworks systems, two for more excavators and one for a dozer.
Sections of duct bank can be prefabricated while the trenches are being excavated, and design files on the excavators' Earthworks systems simplifies setting them accurately into place.Trimble
“We set the excavators up with Trimble units so they would be able to visibly see their dig on a screen inside of their cab,” says Buckley. “The excavators are set up with the same surveying unit that a surveyor with a stick would be using in the field. So that machine shows them the location they’re digging through; they know their path.” This equipment is helping to eliminate a surveyor climbing in and out of trenches, and excavations, or even hanging over the side of embankments to get the right shots.
There’s a BIM team designated to the project, and BIM Coordinator Devin White manages details so elements from Aldridge’s PreFab department align and the job runs smoothly.
“We provided a full 3D model with clash detection” working with the project’s engineers, says Buckley. Ongoing designs were signed off in the coordination model, from which Aldridge personnel could then export the appropriate elements. “We broke that out for our PreFab scope, and then Devin provided the Trimble modeling inside Trimble Business Center for all the machine grade-control systems.”
“Setting up the models for grade control is pretty straightforward,” says White. “The operators, many of them first time users of grade control, really like the technology because they can see what they’re going to be digging and what it’s going to look like, and the machine keeps them positioned accurately. They don’t need a surveyor every time they put a bucket down. We have one excavator without grade control, and nobody wants to use it.”
Trimble Earthworks models are used to represent the exact locations of structures, duct bank and utilities, so the machine operators always know exactly what they need to do. “This made our excavator operators more efficient and reduced rework while reducing emissions and fuel,” said Buckley. “With GNSS, our crews could install objects to within a half-inch tolerance.”
To streamline work on the massive project, the site was broken into phases and survey control points were set throughout the site.
“We had two surveyors on site during peak construction, but usually have just one – and that’s largely thanks to the use of GNSS-enabled equipment,” says Buckley. “We are able to do more with less of the surveyors out there holding a rod.
The work is precise enough to require one full-time surveyor and another part-timer.Trimble
“We don't have to have a full-time surveyor sitting there with the excavator shooting surveys. The excavators can actually do it themselves. So we give them initial layouts, they dig and then we have a surveyor come back and shoot the final.
“The site work is so accurate that the general contractor often looked to us to verify work completed by other contractors. That was a big confidence builder for us, knowing the new program we learned for this project provides value beyond our own scope of work.”
Buckley says Aldridge is ”looking at this as a blueprint for what future data centers will look like for this client. So, this work is really leading the charge” for the company.
BIM crucial to prefabrication
“Our success with PreFab has been one of our competitive advantages to continue to be selected to work alongside these other contractors for this campus.”
Designing, fabricating and installing millions of feet of cable, conduit and manholes requires considerable planning, coordination and collaboration to keep the project safe and on time.
Prefabrication plays such a big role in Aldridge’s work on the project that there’s no way it could be completed on schedule without BIM. Along with clash detection and collaborating with all the project partners, the BIM team’s construction background is critical to understanding the sequencing of work, developing a bill of materials to use on bulk material purchases and identifying prefabrication opportunities.
“We tie our BIM group with our PreFab group, because they do lean heavily on each other,” says Buckley. “All the clash detection between the other trades is done inside the 3D model so that we know what we're going to build isn't going to be in conflict with anybody else’s work. Then we can release it for fabrication.
“There were a few things in this project that were very repetitive. We were working with a very tight schedule, so being able to prebuild duct bank sections while prepping the site allowed us to just set our packages in place when those areas were available, utilizing the Trimble units for layout. We knew how it was going to be installed and what it was going to look like – to speed up the process.
“Once we get one installed, we might tweak it for the next portion of the work for a quicker install.”
White says project teams see clear advantages in production, attitude, quality and safety with the technology additions to Aldridge’s workflow. “There is no way we could have worked as fast and accurately without this technology. We likely would have had to quadruple our workforce to get the project done in the given timeline.”
The value of connected technologies – from BIM to grade control — was quickly proven on this data center job, and the workflow is translating to other Aldridge projects across the country.
Buckley sums it up: “Technology allows us to deliver a product that is not just built ‘as planned,’ but is delivered ‘as intended,’ often allowing us to make recommendations and deliver a final outcome that exceeds original expectations.”
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