Tunnel hole-through
Dismantling the tunnel boring machine 10 days after the hole-through on the Gotthard Base Tunnel in Switzerland.
Tunnel hole-through, also called breakthrough, is the time, during the construction of a tunnel built from both ends, when the ends meet, and the accuracy of the survey work becomes evident. Many tunnels report breakthroughs with an error of only a few inches.
See also
- Cascade Tunnel
- Blue Ridge Tunnel - 6 inches (150 mm)
- Blue Ridge Tunnel - 4 feet (1.2 m) - 1944
