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Digging for innovation: University of Colorado Boulder team to compete in international tunnel boring contest

University of Colorado Boulder sophomore Collin Ruprecht welds while working on a tunnel boring machine in Boulder on Wednesday, July 21, 2021. (Matthew Jonas/Staff Photographer)
University of Colorado Boulder sophomore Collin Ruprecht welds while working on a tunnel boring machine in Boulder on Wednesday, July 21, 2021. (Matthew Jonas/Staff Photographer)

There’s a running joke at Dan Wagner’s house about the DIY welding and construction shop he set up in his backyard. At random moments throughout the day, his roommates yell out “eee-yerrrr,” mimicking the high-pitched grinding noise that’s become a soundtrack to their lives this summer.

“They’re going to miss me when I’m gone,” Wagner said, laughing.

That sound is a byproduct of the project Wagner and a team of University of Colorado Boulder students have spent thousands of hours working on this year: designing and building a tunnel boring machine.

University of Colorado Boulder Senior Ahmed Adan works on circuit boards for the team’s tunnel boring machine at the Aerospace Engineering Sciences building in Boulder on Wednesday, July 21, 2021. (Matthew Jonas/Staff Photographer)

The CU Hyperloop team is one of 12 groups in the world competing to build a machine that will chew through nearly 100 feet of earth to create a tunnel as fast as possible.

The Not-A-Boring competition is hosted by The Boring Company, founded by Elon Musk with the goal of building tunnel infrastructure that allows for rapid transit like high-speed trains.

The contest is cloaked in secrecy, and team project manager Wagner, who graduated from CU Boulder in May, is allowed to say only that the competition is happening soon.

The goal — to dig a tunnel and be able to drive a remote-controlled car through it — sounds deceptively simple.

How do you dig through solid earth? How are you going to power the machine? Where’s the dirt going to go? How do you keep the tunnel from collapsing?

CU Hyperloop team members have spent more than a year trying to answer those questions and are now in the process of building a more than 2,000-pound, 15-foot-long machine to put their answers to the test.

University of Colorado Boulder graduate student Nicholas Kenny uses a bandsaw to cut square steel bars while working on a tunnel boring machine in Boulder on Wednesday, July 21, 2021. (Matthew Jonas/Staff Photographer)

Beyond the experience of competing in an international competition sponsored by Musk — and the acclaim that brings — joining the CU Hyperloop team also gives students high-stakes, hands-on experience they don’t get in the classroom.

“The buck stops with us, so if one of us screws up, the whole team has to come around them and figure out how to fix it,” Wagner said. “It’s totally different from a classroom setting, where a teacher is either looking over your shoulder or ready to bring the hammer down if you screw up.”

A lot of things need to happen all at once in order to dig a tunnel.

The tunnel boring machine’s cutting head — which looks a bit like a cheese grater attachment on a food processor — will turn at 20 revolutions per minute to tear up the earth, propelled by a 200-pound motor that uses repurposed car jacks to push the machine along.

The dirt feeds through the holes in the cutting head into a cavity in the machine, where it mixes with water and is pumped through a swimming pool tube back to the surface.

At the rear of the machine, what looks like a tarp tunnel used for dog agility training will gradually unfold like a massive accordion, lining and supporting the tunnel so a remote-controlled car can drive through it.

The entire digging process will only take a few hours, but to make it happen, students have been working anywhere from 30 to 70 hours a week for more than a year to design and build the tunnel boring machine. There are separate subteams working on power, circuits, software, propulsion, excavation, soil removal, structure and tunnel support.

In late July, teams of students were working in Wagner’s backyard and at a lab on campus.

Students worked at crimping connectors, wiring motors and debugging computer software to make sure all of the machine’s parts can talk to each other and to the students.

From left, University of Colorado Boulder senior Toby Savage and sophomore Max Balasubramaniam work on software for a tunnel boring machine at the Aerospace Engineering Sciences building in Boulder on Wednesday, July 21, 2021. (Matthew Jonas/Staff Photographer)

Senior Toby Savage and sophomore Max Balasubramaniam worked to create a filter for the machine’s raw data so that the team can monitor its positioning and not end up off track.

“Not everything we work on is stuff we were taught in school, so we definitely have to improvise and do a lot of research like we would in any industry,” Savage said. “That’s the hardest part, but also the coolest part.”

It’s also higher stakes than some students are used to, Balasubramaniam said.

“I came in as a freshman, and my classes weren’t doing too much that was supercritical. If I screwed up, there wasn’t much that didn’t work. That’s not the case here. Everything has to work. Everything is mission critical,” he said.

A few miles away, students worked on the steel skeleton of the tunnel boring machine in Wagner’s backyard.

The project is made possible through a combination of private and university funding for the $50,000 budget and sheer force of will.

When the team realized the machine needed a metal sphere to help with maneuvering and that buying one would cost anywhere from $600 to $1,000, students purchased three woks made of 18-gauge steel for $30 apiece, cut them into pieces and rewelded them to fit the machine.

Paying a manufacturer to custom-make the steel rings for the tunnel support system would have cost nearly $6,000, so instead the team ordered a device that bends half-inch steel rods into rings. It takes three students rocking back and forth on the device to bend the steel, but it works.

“Essentially everything we can do in-house, we do in-house because it’s like an order of magnitude cheaper,” Wagner said. “That’s the huge benefit of a team like ours, is that while we don’t have any money, we have a ton of free labor.”

While offering up their free labor, the CU Hyperloop students also gain invaluable experience in engineering.

Senior Cody Wheeler said he’s enjoyed helping younger students get involved and learn systems like computer-aided design.

“Then there’s the entire innovative design aspect of things, where we have to think of our own original ideas and actually be able to implement them right now, which is awesome,” he said.

Sophomore Collin Ruprecht said he joined the project not expecting a lot of responsibility because he was a freshman.

“Suddenly I was doing a large part of a major subsystem,” he said. “I was really glad that I was able to get a lot of experience — and it wasn’t just like, ‘Here, hold a wrench.’”

Since July, the team has moved the tunnel boring machine from Wagner’s backyard into a workshop in Lafayette. They’re still finishing construction and are planning to conduct smaller digging tests before the competition.

At the end of the day, the competition is more about innovation and recruitment than it is the actual tunnels, Wagner said.

“There’s really no way to get experience with tunnel boring, as it stands right now, except through this competition,” Wagner said. “There’s also new tech being developed. As far as we’re aware, nobody’s ever tried this kind of tunnel support system before, so we’re going to be the first, and we’ll see if it works.”

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