Full-face hard-rock tunnel boring machine (Mittry Mole)
Tuneladora de roca de cara completa (Mittry Mole)
- Date
- 1952-1956 · confidence medium
- Place
- Pierre, South Dakota, United States
- Credited to
- James S. Robbins
- Field
- Tools
⚠️ Disputed: the sources disagree.
What it is
Robbins's 'Mole' bored the Oahe reservoir tunnel with a rotating steel-toothed head that breaks the full face and removes spoil by conveyor. It made continuous excavation in hard rock and long tunnels viable.
There were earlier attempts (Beaumont, 1881; Wilson's 1851 machine); Oahe's is considered the first successful one, but the first run (1952-53) suffered from wear and was improved in 1956 with disc cutters.
What it led to
- Channel Tunnel, metros and water tunnels
- hard-metal disc cutterheads
- fewer deaths and accidents compared to blasting