Snail’s pace times two

Trend-setting: a team of students from Switzerland has developed an innovative boring machine – as its submission to a tunnel building competition organized by Elon Musk.

At the test site in Las Vegas, the team not only had to cope with the heat and sandstorms when unpacking the equipment. They were also interrupted by a thunderstorm and power outages.

Groundhog Alpha is the name of the seven-meter-long drill weighing two-and-a-half metric tons. With a shape recalling a worm, it has been designed and built by Swissloop Tunneling, a team of 40 students from the Swiss Federal Institute of Technology in Zurich and the University of St. Gallen.

With their Alpha Groundhog, the team reached the finals of the tunneling technology contest “Not-a-Boring Competition” initiated by Elon Musk in Las Vegas. His visionary Hyperloop – or short, the “Loop” – is a tunnel system in which electric vehicles transport passengers to their destinations emission- free. It requires construction technology that is much quicker, requires less space, and is more highly automated. The subterranean drills need to work “faster than at a snail’s pace.” 400 teams had applied to enter, with twelve – the “Digging Dozen” – being invited to Las Vegas. In the end, only the engineers from Zurich and the Technical University of Munich were invited to participate. The Swiss came top in the “Innovation and Design” category and finished second overall in the competition.

Gebrüder Weiss served as the Zurich team’s logistics partner and sponsored the transport of its drill. The container was collected by truck in Dübendorf near Zurich, from where it was taken to the German port of Hamburg. A transatlantic crossing followed to Houston, Texas, with the drill completing the final leg of its journey by road to Las Vegas.

From the Alps to the desert: the students help load up their equipment in Dübendorf.

The civil engineer Lukas Heller is currently completing the final year of his Master’s degree at the Institute of Technology in Zurich. He was one of the first members to join the Groundhog Alpha team. In the year preceding the competition, he headed the groups that were developing the drill head, the drive system, and the mining and extraction system. “The competition was the spark it took to pursue research in this area,” he says. “Today, it isn’t quite the only reason why our project exists. We pushed ourselves to the limit in the competition, but also when it came to innovating. I think we scored highly in that respect.”

Groundhog Alpha is more maneuverable than conventional boring machines. The drill head is held in place by a custom-made hydraulic hexapod system. Six precision hydraulic cylinders, which were contributed by the project’s industry partner Hagenbuch Hydraulic, can thus move the drill which has six degrees of freedom. In addition, the drill can effectively create the lining as it advances. “Engineers all dream of a drill that can build the tunnel wall itself. We are pioneers in this field,” says Heller. “Normally, this task is performed using prefabricated elements, a kind of tubing which has to be inserted into the tunnel somehow. By contrast, we have a twin-component polymer system. Using a 3D printer integrated into the machine, the material is applied to a fiberglass lamella as it unrolls. This solidifies very quickly and is immediately able to withstand pressure.”

“We have parties among our sponsors who can already envisage concrete applications for this technology,” says Heller’s colleague Luca Erdmann. The business administration student is a project manager at Swissloop Tunneling – with responsibility for liaising with industrial partners and sponsors. “We now want to run trials with the drill and explore its full potential. We can imagine individual elements – such as the 3D printing – being scaled up or down and incorporated into existing machinery.”

And we don’t have to wait until the Groundhog Alpha technology has been rescaled completely and Elon Musk has built his gargantuan, four-meter-wide Hyperloop tubes. Channels with a diameter of 50 centimeters, such as those Groundhog Alpha is already drilling, are also required for laying fiber-optic cables and sewage systems. In the majority of cases, tunnel-boring machines are not being deployed for this at present. Ten-meter-long tubes are simply being thrust into the ground. “Our system offers genuine advantages,” says Heller. “We don’t use straight, ten-meter tubes. Our flexible drill head enables us to cut even tight bends in the channels.”

And how fast does that work? Heller explains that this depends on the size of the tunnel. The large boring machines used in road and railway applications are particularly slow, managing only between 0.05 and 0.1 centimeters per second. That’s when they are moving at all. Most of the time there is no forward progress because the cutters are switched off while the tubing is inserted. “The speed we targeted is around 0.5 centimeters per second,” says Heller. And that’s twice as fast as a snail can move.

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