A humanoid robot armed with a chainsaw is now trimming trees along Japanese railway lines, and it’s a human operator, not artificial intelligence, pulling the strings.
JR East, one of Japan’s major railway companies, has put the machine to work along its Koumi Line in central Japan, where overgrown branches threaten to interfere with passing trains. The robot, built by Japanese manufacturer Nippon Signal and named ZIZAI ZX-3, uses one mechanical arm to grip a branch while the other operates the chainsaw. Its upper body extends from a boom mounted on a specialized maintenance vehicle, letting it reach high above the tracks without a person climbing up there.
Nippon Signal delivered the ZX-3 to JR East earlier this year, and the robot began full-scale maintenance work on the Koumi Line in October. JR West, a separate company, has already been running a related robotic system since July 2024.
The point of the machine is straightforward: keep workers out of harm’s way. Cutting back vegetation near train tracks has traditionally meant sending crews up with heavy cutting equipment, often near electrical infrastructure, where a single mistake can be costly or dangerous. The ZX-3 instead lets an operator control the robot’s arms and chainsaw remotely from a safer position, deciding where to position the blade and when to cut.
Japan is also grappling with a shortage of skilled labor, giving railway operators extra incentive to find ways to make maintenance jobs less physically demanding. JR East has separately been shifting some Koumi Line maintenance from overnight hours into daytime since 2022, a change that sometimes forces temporary train cancellations but gives crews better working conditions.
Nippon Signal says the robot’s current job is limited to cutting trees and branches, but the company hopes to equip it with additional tools for other maintenance tasks down the road. JR East is also investing more broadly in artificial intelligence and robotics for equipment inspections across its network.
Despite that broader push toward automation, JR East has not announced any timeline for making the chainsaw robot operate without a human controller. For now, every cut the ZX-3 makes is directed by a trained person watching from a distance, not a machine making the call on its own.
