The Gotthard Tunnel (German: Gotthardtunnel, Italian: Galleria del San Gottardo) is a 15.003-kilometre-long (9.322 mi) railway tunnel and forms the summit of the Gotthard Railway in Switzerland. It connects Göschenen with Airolo and was the first tunnel through the Saint-Gotthard Massif in order to bypass the St Gotthard Pass. It is built as one double-track, standard gauge tunnel. When opened in 1882, the Gotthard Tunnel was the longest tunnel in the world.
The tunnel rises from the northern portal at Göschenen (1,106 m (3,629 ft)) and the highest point (1,151 m (3,776 ft)) is reached after approximately 8 kilometres (5.0 mi). After two more kilometers, the border between the cantons of Uri and Ticino is passed; after another 5 kilometres (3.1 mi), the tunnel ends at the southern portal near to Airolo (1,142 m (3,747 ft)). The trip takes about seven to eight minutes by train. Services are operated by the Swiss Federal Railways.
The Gotthard Railway Company was founded in 1871 under the stewardship of the Swiss industrialist Alfred Escher, who had created the Schweizerische Kreditanstalt in 1856. Despite initial difficulties to finance the project, and resulting costs of about 11% over budget, the financing was shared among private and public investors from Switzerland (20M CHF), Italy (45M CHF) and the German Empire (20M CHF). The bidding war between an engineering company from Geneva and Italy was fought, and finally, the Swiss engineer Louis Favre won the project with an estimated cost of 2830 Swiss francs per meter. Because of his low bid, and the extra costs during construction, Favre increasingly found himself at odds with Swiss politicians and investors alike.
The tunnel was built from 1871 to 1881 and marked the first large-scale use of dynamite which had been patented in 1867. Construction was supervised by the Swiss engineer Louis Favre, who suffered a fatal heart attack inside the tunnel in 1879. Construction was difficult due to financial, technical and geological issues, the latter of which led to the death of around 200 workers (the exact number is not known) mainly due to water inrushes; many were also killed by the compressed air-driven trains carrying excavated material out of the tunnel. There were also serious health issues caused by an epidemic of hookworm infection (Ancylostoma duodenale). Medical investigations led to "major advances in parasitology, by way of research into the aetiology, epidemiology and treatment of ancylostomiasis". A strike of the workers in 1875 was crushed by the Swiss Army, killing four and wounding 13.
A memorial for the dead workers was erected in 1932 near the station building at Airolo. The memorial contains a relief by Vincenzo Vela from 1882/1883, titled "Vittime del lavoro" (Victims of labour).
The tunnel was opened for traffic in 1882, operated by the private railway company Gotthardbahn, which ran from Lucerne to Chiasso at the Italian border. The Gotthardbahn was integrated into the Swiss Federal Railways in 1909. In 1920, the first electric trains were run through the Gotthard Tunnel. Initially the voltage had to be reduced from the desired 15 kilovolts to 7.5 kV, because the grime deposited on the insulators by the steam locomotives encouraged excessive arcing. However, in May the next year, steam was replaced entirely by electric traction, and the problem of soot and grime was eliminated.
Until the opening of the Gotthard Road Tunnel in 1980, the Swiss Federal Railways offered piggyback services for cars and trucks through the Gotthard Tunnel. Today, that service exists as the rolling highway from the German to the Italian border and aims to reduce truck traffic on Swiss expressways. An improvisational piggyback service from Göschenen to Airolo was offered during the two-month closure of the Gotthard Road Tunnel in 2001.
The adjacent ramps include several turn tunnels (see Table of turn tunnels). The nearby Gotthard Road Tunnel was opened in 1980. A second railway tunnel, the Gotthard Base Tunnel, much longer and at a lower elevation than the Gotthard Tunnel, opened on 1 June 2016.