The Gotthard Base Tunnel (map), a railway tunnel in Switzerland, isn’t complete yet, but in 2015 — after 22 years of construction — it will be the longest transportation tunnel in the world, running 35 miles through the Swiss Alps. It will eventually cut the travel time between Zürich and Milan from 3.5 hours to 2.5. Four tunnel boring machines are working the job: “2 southbound from Amsteg to Sedrun, 2 northbound from Bodio to Faido and Sedrun,” according to Wikipedia. The machines cut away at the rock at a rate of 100 feet per day in optimal conditions. That explains the 22 years of construction!
The Seikan Tunnel in Japan is the current world record holder, clocking in at 33.49 miles. Almost half of the length runs under the Tsugaru Strait, which connects the island of Honshū to Hokkaidō in northern Japan, and bridges the Sea of Japan with the Pacific Ocean. The tunnel opened on March 13, 1988, after 17 years of construction. Two stations are located in the tunnel: Tappi-Kaitei Station and Yoshioka-Kaitei Station, both of which were the first train stations in the world built under the sea. Yoshioka-Kaitei has since been demolished to make way for the Hokkaido Shinkansen project, which will eventually facilitate high-speed trains in the Seikan.
The Channel Tunnel, or Chunnel (map), linking the United Kingdom and France under the English Channel, takes the second (completed) spot at 31 miles long. While it’s a few miles shorter than the Seikan Tunnel, the Chunnel’s underwater segment is longer than that of the Seikan, making it the world’s longest underwater tunnel. The construction took 13 7 years, from 1987 to 1994, with over 13,000 workers involved in construction. Eleven tunnel boring machines were used — 6 on the English side, and 5 on the French side — and the sides met on December 1, 1990. 8.2-million passengers traveled the Chunnel via Eurostar in 2005, and numbers are expected to grow even larger when the Channel Tunnel Rail Link extends to London later this year. When the link is completed, a train trip from London to Paris will take 2 hours and 15 minutes.
The Lötschberg Base Tunnel in Switzerland runs 21.5 miles from Frutigen, Berne to Raron, Valais. When it opens in December of 2007, it will be the longest land tunnel in the world until the Gotthard Base Tunnel opens in 2015. “To dig the Loetschberg, some 16 tons of explosives were used and enough rock was excavated to pack a freight train 2,500 miles long – stretching across Europe from Lisbon, Portugal, to Helsinki, Finland,” according to this report from MSNBC.