Tunnel hole-through

{{Short description|When the two sections of a tunnel under construction meet}}

{{Notability|date=May 2014}}

Image:TBM S-210 Alptransit Faido East.jpg 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,{{cite news |title=Governor Rockefeller and Mayor Lindsay Attend 'Holing Through' of 63d St. Tunnel |url=https://select.nytimes.com/gst/abstract.html?res=FA0A12FF3E591A7493C3A8178BD95F468785F9 |newspaper=The New York Times |date=October 11, 1972 |accessdate=January 24, 2017}} 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 – {{convert|6|in}}
• the 1944 Blue Ridge Tunnel replacement – {{convert|4|ft}} - 1944
• the Lötschberg Base Tunnel – 10 cm[http://www.swissinfo.ch/eng/index.html?cid=4481072 Lotschberg]
• the Holland Tunnel - 1 cm{{Cite web|title=ASCE Metropolitan Section - Holland Tunnel|url=https://www.ascemetsection.org/committees/history-and-heritage/landmarks/holland-tunnel|access-date=2020-11-21|website=www.ascemetsection.org}}