Autonomous Tunneling Robot TunnelBot: Moving Subway Construction Beyond Human Crews

The TunnelBot autonomous tunneling robot, jointly developed by Swiss tunneling equipment maker Herrenknecht and US robotics firm Boston Dynamics, completed its first bore on Singapore's Thomson-East Coast Line extension. The milestone marks the arrival of a fully autonomous era for urban subway construction.

At the heart of TunnelBot is an autonomous decision module built on Boston Dynamics' Atlas robot control system. Traditional tunnel boring machines require operators in a control cabin to continuously monitor boring parameters and make real-time adjustments. TunnelBot automates those decisions entirely. The robot identifies geological changes ahead on its own and dynamically adjusts cutterhead speed, thrust, and ground support plans.

The Thomson-East Coast Line extension bore stretches 347 meters at a diameter of 6.2 meters. TunnelBot drove the segment continuously for nine days without human supervision, averaging 38.5 meters per day. The pace is slightly slower than an experienced human operator, but the robot can run around the clock.

On safety, TunnelBot's autonomous decision system halts boring immediately and reports when it encounters unexpected obstructions. During the first bore, the robot identified and automatically avoided two unregistered abandoned pile foundations, preventing potential equipment damage and safety incidents. Aaron Saunders, engineering vice president at Boston Dynamics, said this kind of autonomous obstacle avoidance is not available on conventional boring machines.

On the technical side, TunnelBot retains all the core components of a traditional shielded boring machine, including the cutterhead, propulsion system, muck removal, and segment erector. The autonomy upgrade focuses on control, with Boston Dynamics' motion planning algorithms converting the machine from manually operated to self-directed.

Chua Chong Kheng, deputy chief executive at Singapore's Land Transport Authority overseeing metro construction, said TunnelBot validates a new possibility for urban infrastructure. Singapore plans to apply the technology to four new metro lines over the next five years and expects to save about 280 million dollars in labor costs.

On the workforce side, traditional Singapore metro construction relies on about 40 workers coordinating underground. With TunnelBot deployed, that number drops to 12, mostly handling segment assembly, material transport, and equipment maintenance that cannot be automated. Chong Kheng said the agency will work with unions to retrain displaced workers for TunnelBot operations and maintenance roles.

Environmentally, TunnelBot's precise control reduces over-excavation and under-excavation, limiting disturbance to surrounding rock. The volume of spoil generated is about 15 percent lower than with conventional methods. Continuous robot operation also cuts equipment idle time, trimming energy use by 8 percent.

Internationally, Herrenknecht has received intent orders from metro projects in London, Tokyo, and Dubai. Boston Dynamics CEO Robert Playter said global urban rail construction will reach 1.4 trillion dollars over the next decade and TunnelBot could become one of the defining technology solutions for that market.