Tunnel Construction Robot: From Brunel to ABB

Digging a tunnel used to mean hundreds of people at the face with picks, shovels and explosives. Today a tunnel boring machine does the cutting, but some of the most dangerous jobs are still done by hand, such as changing worn cutters in a pressurised chamber or loading explosives into a rock face. A tunnel construction robot is meant to take over those jobs. This post follows the work from Marc Brunel's shield under the Thames to modern boring machines, looks at the new Hudson River rail tunnels that started boring in September 2026, and shows where ABB robots already work underground.

Workers walk past the cutterheads of new Crossrail tunnel boring machines at Royal Oak portal, London, March 2012. Photo: Annie Mole / Wikimedia Commons (CC BY 2.0)

How tunnels were dug by hand and by shield

For centuries tunnels were dug by miners with hand tools, and later with drills and gunpowder or dynamite in hard rock. Soft ground under rivers was worse, because water and mud could break in at any moment. Marc Isambard Brunel's answer was the tunnelling shield, a frame that held up the face while men dug behind its protection. He used it to dig the Thames Tunnel in London from 1825, and the tunnel opened in 1843. Inside the shield, men still dug the face by hand from small cells in the frame.

Inside the restored shaft of Brunel's Thames Tunnel at Rotherhithe, now part of the Brunel Museum, 2024. Photo: Z22 / Wikimedia Commons (CC BY-SA 4.0)

Engineers soon tried machines. Major Frederick Beaumont patented a boring machine in 1863, and Major Thomas English improved it in 1880 with cutting discs on rotating arms. Their machine cut 1,840 metres through chalk for an early Channel Tunnel attempt between June 1882 and March 1883. Under the Hudson, the Greathead shield was used to build the Hudson and Manhattan Railroad tubes between 1890 and 1908, with air compressed to 2.4 bar to hold back the river.

An abandoned Greathead tunnelling shield at the end of platform 10 at Moorgate station, London. Photo: Firefly / Wikimedia Commons (CC BY-SA 4.0)

On a modern tunnel boring machine, a rotating cutterhead with steel disc cutters grinds the face, and the machine lines the tunnel behind itself as it moves. Disc cutters wear out fast. On the Herrenknecht machine that dug Hamburg's fourth Elbe tunnel, 14.2 metres across, crews changed 300 discs and 50 carbide hammerheads in the first 2,000 metres. Bouygues later developed Telemach, a robot arm that cleans and changes disc cutters, and first used it on a 17.6 metre Herrenknecht machine for the Tuen Mun to Chek Lap Kok link in Hong Kong, controlled from the operator cab by camera.

A disc cutter from Åsa, the tunnel boring machine that dug Sweden's Hallandsås tunnel. Photo: Erik Lundin / Wikimedia Commons (CC BY-SA 3.0)

What tunnel robots do on today's projects

In New York, on 28 September 2026, the Hudson Tunnel Project, part of the Gateway Program, began boring with the first of two Herrenknecht machines. They will cut about a mile through the hard rock under the Palisades in New Jersey to an access shaft in Weehawken, at around 30 feet a day including planned maintenance stops. After about a year, a second pair of machines will take over for the section under the river. These are the first new rail tunnels under the Hudson since 1910.

The rear of a tunnel boring machine being assembled for the Warsaw metro, 2012. Photo: Crusier / Wikimedia Commons (CC BY-SA 3.0)

Telemach shows what a cutter changing robot has to handle. It reaches into the excavation chamber, can work at pressures of up to 7 bar, and the operator controls it remotely through cameras instead of sending people into compressed air. Research on the system describes it as built around a six-axis KUKA industrial arm with a new cutter holder and end effector. Tunnels dug by drill and blast face a different risk. After each blast, crews spray concrete onto the fresh rock to hold it up, and someone has to load explosives into the drilled holes at an unsupported face.

A worker sprays concrete onto steel mesh by hand at a building site in Cologne, 2013. Photo: Raimond Spekking / Wikimedia Commons (CC BY-SA 4.0)

That second job is where ABB robots have gone underground. ABB, Boliden and LKAB completed tests of the ABB Robot Charger at Boliden's Garpenberg zinc mine, northwest of Stockholm. An ABB industrial robot on a carrier vehicle finds the drilled holes with a vision system and fills them with explosives, while a second arm assembles the primer and detonator, so nobody stands near the face. ABB says larger mines blast up to 15 times a day, and the system can be retrofitted to any truck. Our post on robot blast hole charging covers the mining side in detail.

The ABB Robot Charger finds drilled holes in a rock face and installs explosive charges. Photo: ABB

Where tunnel construction robots go next

Drill and blast tunnels for roads and railways use the same face charging step as mines, so a charger like ABB's could, as a possibility, move into tunnelling. On boring machines, the next steps are robots that inspect, measure and replace cutters and help place the lining segments. Large ABB arms such as the IRB 6700 or IRB 7600 could carry heavy cutter tools as a possibility, although ABB has not announced a TBM project. New machine designs keep appearing too: in 2026 China introduced Lucky Dragon, a 4.5 metre hard rock machine with a hybrid boring and blasting cutterhead.

An ABB IRB 6700 printing concrete station parts for JR West in Serendix's factory. Photo: ABB

People at home mostly meet tunnels as commuters and water customers. Washington's DC Water began a 20 year tunnel programme in 2013 to cut sewer overflows, using machines with cutting heads built in Germany. In factories, robots already help make tunnel parts: concrete lining segments are cast in plants, and cells that handle moulds or reinforcement can be planned and checked in RobotStudio before they are built. A segment plant is dry and orderly, which suits today's industrial robots far better than the tunnel face does.

The 26 foot cutting head of a DC Water tunnel boring machine for the Clean Rivers Project, 2014. Photo: DC Water via Wikimedia Commons (public domain)

A cutterhead full of mud, rock and water is a hard place for any robot, and cutters, bolts and holders have to be designed so a machine can grip them. Space inside a TBM is tight, so each added robot competes with conveyors, cables and crews, and it adds cost to a machine that is already very expensive. Safety rules for compressed air work and blasting are strict, and robots must fail safely. Tunnel crews also need people who can run and repair robots deep underground, often far from the nearest workshop.

The ABB Robot Charger on its carrier vehicle underground, with the arm reaching toward the rock face. Photo: ABB

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