TerraWorm Deep Dive: Biomimetic Earthworm Robot Burrows Through Soft Soil to Lay Underground Pipelines

TerraWorm Deep Dive: Biomimetic Earthworm Robot Burrows Through Soft Soil to Lay Underground Pipelines

Urban underground pipelines — water, gas, electricity, fiber optics — are expensive and disruptive to install and maintain. Traditional methods require road excavation, and laying a 500-meter pipeline can cause weeks of traffic disruption. TerraWorm, developed by the Robotic Systems Laboratory at ETH Zurich, offers a fundamentally new approach.

Lessons from the Earthworm

TerraWorm's design is inspired by how earthworms move. An earthworm anchors its front end by expanding it within the soil, then contracts its rear to push forward, alternating between the two. TerraWorm uses a similar anchor-and-advance mechanism: the robot's front expansion ring provides anchoring force in the soil, a mid-section hydraulic cylinder pushes the rear forward, while the front simultaneously excavates.

The robot measures approximately 2 meters in length and 15 centimeters in diameter, composed of six independently expandable and contractible body segments. Each segment's outer surface is covered with micro-spine arrays, mimicking the setae on an earthworm's body wall to enhance grip in loose soil.

Autonomous Navigation

TerraWorm is equipped with an inertial measurement unit (IMU) and ultrasonic sensors, enabling autonomous navigation at depths of 30 to 200 centimeters underground. The system uses pre-loaded underground pipeline maps to plan its path while using ultrasound to detect obstacles ahead in real time, such as rocks or existing pipelines.

"Earthworms don't run into rocks in the soil — they go around them," said project lead Professor Brad Nelson. "TerraWorm's navigation algorithm uses a similar strategy: upon detecting an obstacle, it automatically adjusts its excavation direction."

Engineering Applications

The Zurich municipal government used TerraWorm in August 2030 to lay a 300-meter fiber optic pipeline. Traditional excavation would have required 3 weeks and 450,000 Swiss francs. TerraWorm completed the job in 4 days for 120,000 Swiss francs, with zero impact on surface traffic.

"The greatest value isn't just saving money — it's not having to close roads," said Klaus Müller, Zurich's head of municipal engineering. "Beneath the roads of Zurich's old town lie medieval stone foundations. Every excavation damages them once more. TerraWorm passes underneath, and the road surface doesn't budge."

Limitations

TerraWorm currently operates only in soft soils (clay, loam, sand) and cannot work in rock or hard ground. Its excavation speed is about 2 meters per hour, slower than a traditional tunnel boring machine, but conventional TBMs require large-diameter shafts as launch points. TerraWorm needs only a 20-centimeter entry hole.

Nelson's team is developing a rock-capable version that will use rotating cutting heads instead of expansion anchoring. "Our long-term vision is for TerraWorm to become a universal platform for underground construction," Nelson said. "Just as drones transformed aerial photography, TerraWorm can transform subsurface construction."

TerraWorm's commercialization is handled by Bionic Underground, an ETH spin-off that has received 2 million Swiss francs from the Swiss Innovation Agency and plans to begin sales to European municipal authorities in 2031.