ENGINEERING & INNOVATION · GERMANY
Herrenknecht
The boring machines that ate the Alps — and dig the world's cities
Photograph · A tunnel boring machine, shown as a scale model — “Tunnel Boring Machine Model - Herrenknecht Mixed Shield, 'Joan', 2018” by Photographer: Jon Augier,Modelmaker: Mark O'Brien — CC BY 4.0 · Credits
01 In brief
On the Upper Rhine plain at Schwanau, within sight of the Black Forest, Herrenknecht builds the machines that dig the world's tunnels. Founded in 1975 by engineer Martin Herrenknecht with a handful of employees, the family-owned company has become the world's leading manufacturer of tunnel boring machines — the steel cylinders that grind through rock beneath cities and mountains alike.
Its most famous worksite lies inside the Alps: the Herrenknecht gripper machines that bored the 57-kilometre Gotthard Base Tunnel set world records for hard-rock advance rates on their way to completing the longest railway tunnel on Earth. Around that pedigree stands a catalogue spanning machines from under a metre to nineteen metres in diameter, for metro lines, water tunnels, mines and utility networks.
02 Why it's interesting
- 01 Mechanised tunnelling replaced the drill-and-blast era's armies of miners with a factory line underground: a tunnel boring machine bores, supports and lines the tunnel behind it in one continuous process.
- 02 The Gotthard drives proved the extreme case — years underground in hard Alpine granite, steered to meet within centimetres.
- 03 The product range covers nearly every ground on Earth — soft clays, boulders, hard rock, mixed conditions — with shield types matched to each.
- 04 It is a family firm from a village, not a conglomerate: Schwanau's machine halls supply projects from city metros to deep drainage tunnels beneath the sea.
03 How it works
A tunnel boring machine is a self-propelled factory: a rotating cutterhead at the front, thrust and steering in the middle, and an erector that builds the tunnel's concrete lining as the machine advances.
Herrenknecht's catalogue is organised by ground. Gripper machines brace themselves against the tunnel walls to attack hard rock; EPB (earth-pressure-balance) shields and Mixshields keep soft, waterlogged ground stable by pressurising the face and conditioning the spoil into a controllable paste; multi-mode machines switch between methods as the geology changes along a single alignment.
Behind the cutterhead, conveyors move excavated rock to the logistics train, hydraulic jacks push off the finished lining to advance the machine, and guidance systems hold the bore true over kilometres. On the Gotthard drives the machines ran for years on end in granite — a demonstration, at scale, of what continuous mechanised excavation can achieve in speed and safety.
| Founded | 1975, Schwanau (Allmannsweier) |
|---|---|
| Founder & owner | Martin Herrenknecht |
| Employees | ~5,000 worldwide |
| Revenue | €1.29 billion (2024) |
| Machine diameters | From below 1 m to 19 m |
| Signature project | Gotthard Base Tunnel boring machines |
Figures per Herrenknecht's company profile and published reporting.
04 The organisation behind it
Herrenknecht remains family-owned and run from Schwanau in Baden-Württemberg, close to the Swiss and Alsatian borders. Alongside traffic tunnelling it operates divisions for utility tunnelling and vertical drilling, plus a worldwide network of subsidiaries. Its founder, awarded one of Germany's highest technology prizes in 2015 for his life's work, still leads the company.
05 In the real world
Mechanised tunnelling quietly underwrites modern urban life: metros, road tunnels, drinking-water and wastewater conduits, electricity and data ducts — much of what makes dense cities liveable passes through bores cut by machines of this maker.
The Gotthard Base Tunnel demonstrated the Alpine payoff: freight now crosses Switzerland in hours, through rock first touched by Herrenknecht cutterheads.
06 Can you visit?
The Schwanau site receives booked visitor groups — engineering associations, delegations and school classes — rather than walk-in tourists; check the company's visitor pages before travelling.
The company's most visible products are, by definition, underground: the best public viewing of a Herrenknecht machine in action is a construction-site visitors' gallery, when one is offered on a project near you.