June 1 marks the official inauguration of the world's longest rail tunnel. Sika's front-line technologies and construction expertise played a crucial role in the successful completion of one of Europe's most important infrastructure projects.

The 57 km-long Gotthard base tunnel in Switzerland is both a novelty and a remarkable achievement in tunnel engineering. It is the longest rail tunnel in the world and passes through one of the highest Alpine massifs. It runs some 2,000 meters below the mountain summits and, even at its highest point, is still only around 550 meters above sea level. The new rail section will reduce the time that massive freight and modern high-speed trains need to travel from Zurich to Milan by around one hour.

The number of daily rail passengers is expected to increase from the current rate of 9,000 people to 15,000 by 2020, according to the Swiss federal railway service.


  • Length: 57 kilometres (the longest rail tunnel in the world)
  • Maximum speed: Freight trains 160 km/h, passenger trains up to 250km/h
  • Construction period (excluding exploratory work): 17 years
  • 28.2 million tonnes of material excavated
  • Qualification process 1996 – 2002 with extensive tests and prior investment of over 3 million CHF
  • Project participants: 2,600 people
  • Cost: 10 billion CHF


The client specified an extremely long service life, during which time the concrete and waterproofing systems should require no significant maintenance. In the course of an elaborate prequalification process, Sika entirely fulfilled all the stringent requirements. The partly newly developed products underwent rigorous practical tests by official testing laboratories prior to mass production and application.

The high-grade shotcrete used to support the tunnel excavation served as the base for the Sikaplan® and Sarnafil® waterproof membranes. The concrete lining was then placed using Sika admixtures so as to achieve the high degree of precision required for the tunnel surface geometry.

The immensely challenging quality requirements were met through the use of Sika's durable solutions for waterproofing, fire protection, coatings, and concrete and shotcrete production.


For Sika too, the Gotthard project defies all superlatives. Since the start of preliminary testing in 1992, Sika's employees have worked more than 210,000 hours on the once-in-a-lifetime project.

Approximately 20,000 tonnes of concrete admixtures were used for the concreting works. The tunnel was waterproofed with 3.3 million m² of Sikaplan® membranes – roughly the size of 330 soccer pitches. Overall, some 40,000 tonnes of Sika products, equivalent to 1,700 freight wagons, were transported to the site.

Video: The longest rail tunnel worldwide goes live