Tunnel hole-through

Tunnel hole-through, also called breakthrough, is the time, during the construction of a tunnel built from both ends, when the ends meet,[1] and the accuracy of the survey work becomes evident. Many tunnels report breakthroughs with an error of only a few inches, for example:

• the 1858 Blue Ridge Tunnel – 6 inches (150 mm)
• the 1944 Blue Ridge Tunnel replacement – 4 feet (1.2 m) - 1944
• the Lötschberg Base Tunnel – 10 cm[2]

Dismantling the tunnel boring machine 10 days after the hole-through on the Gotthard Base Tunnel in Switzerland.

See also

• Cascade Tunnel

References

1. "Governor Rockefeller and Mayor Lindsay Attend 'Holing Through' of 63d St. Tunnel". The New York Times. October 11, 1972. Retrieved January 24, 2017.
2. Lotschberg

External links

• Gautrain tunnel breakthrough
• Brisbane Clem 7
• Gotthard tunnel
• Lotschberg - 10 cm