It’s not every day that a railway tunnel celebrates its completion with a specially commissioned orchestral score and interpretive dancers in orange jumpsuits and hard hats. But Switzerland’s Gotthard Base Tunnel (GBT) is not your everyday railway tunnel. The “Constructed Marvels of the World” club just got a new member.
The Gotthard Base Tunnel is now officially the world's longest and deepest traffic tunnel.
The Gotthard Base Tunnel (so named because it bores directly through the base of the Saint-Gotthard Massif, a mountain group within the Alps range) had its lavish grand opening on June 1, 2016, and is now officially the world's longest and deepest traffic tunnel. At a total 94.34 miles of tunnels and shafts and at a depth of 2600 feet, the tunnel took some 17 years to build, and during that time captured the imagination of the Swiss as they watched the engineering marvel unfold at a cost of $10.1 billion.
The GBT, which connects the Swiss districts of Erstfeld and Bodio, tentatively began its journey through the middle of the Alps range with drill soundings in 1993. Drilling operations were formally completed in a Breakthrough Ceremony on October 15, 2010 when “Sissi”, one of four enormous Herrenknecht Gripper Tunnel Boring Machines, chewed ceremoniously (and somewhat cautiously, given the presence of dignitaries gathered there) through the final 180 centimeters of Alpine limestone, to the applause of hundreds of jubilant tunnel workers and engineers. The GBT will open to actual rail traffic in December 2016.
The showpiece Gotthard Base Tunnel is the first “flat route” through the Alps, and has raised hopes that the region’s environmental issues will be mitigated somewhat by the “road to rail” shift of the massive amounts of freight that pass through this high-traffic transit route. The planning and approval processes of the GBT quickly followed a 1992 referendum in which a majority of the Swiss people approved of the project, called the Alp Transit Project. An early keynote of the proposed new tunnel was its rescue of the region's environment.
The standard heavy freight trains (3,500 long tons) which the GBT was specifically designed to accommodate will be able to carry substantially more freight tonnage than the 1500 long ton trains the older Gotthardbahn rail line presently allows. By design, this much increased freight capacity will replace a daily torrent of exhaust-spewing trucks that for decades have polluted the gorgeous Alpine environment in this busy shipping corridor. The GBT has the added benefit of effectively joining northern and southern Europe with a much faster passenger rail connection than was previously available, and a capacity of up to 260 freight trains per day, versus the 180-train capacity (and smaller trains) of the existing historic rail line, the Gotthardbahn rail tunnel, which dates to 1882.
One unavoidable natural feature of the Gotthard Massif gave the geologists early jitters. They realized the Gotthard Base Tunnel would traverse what’s called the Piora Syncline; a fault zone they feared would be comprised of the same finely granulated dolomite that characterizes the mountain surfaces in that area. That would mean boring through “flowing ground”; powdery loose soil under extreme water pressure whose expensive effect would be to “squeeze” the enormous Tunnel Boring Machines until they jammed, causing delays and mountain-sized headaches. Their findings informed their decision to specially bolster and support that part of the tunnel as drilling proceeded. By the time the GBT was completed, 28 million tons of earth had been moved at a rate of about 90 feet a day. Yes, slow and steady works every time. Welcome to the world's newest construction wonder.