Engineering:Tunnel hole-through

From HandWiki
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,[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]
  • the Holland Tunnel - 1 cm[3]

See also

  • Cascade Tunnel

References

External links