No mountain too small

The 57-km Gotthard Base Tunnel in Switzerland is the longest rail tunnel in the world. Opened on June 1, this remarkable achievement in tunnel engineering passes through one of the highest Alpine massifs and runs some 2 000 m below the mountain summits. Even at its highest point, the tunnel is still only around 550 m 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. Creating it, however, required high levels of expertise.

From its early days, Swiss specialty chemical company, Sika, was involved in the construction of the Gotthard railway tunnels in Europe. Sika-1 earned industry acclaim and commercial success in 1918 when the first Gotthard railway tunnel needed waterproofing. Today, the new Gotthard Base Tunnel is once again a high-profile project for Sika.  

Sika’s front-line technologies and construction expertise played a crucial role in the successful completion of what is one of Europe’s most important infrastructure projects. The immensely challenging quality requirements were met through the use of Sika’s durable solutions for waterproofing, fire protection and coatings, as well as concrete and shotcrete production.

In the course of an elaborate pre-qualification process, Sika fulfilled all the stringent requirements. For example, an extremely long service life, during which time the concrete and waterproofing systems should require no significant maintenance.

The 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, to achieve the high degree of precision required for the tunnel surface geometry.

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

Approximately 20 000 t of concrete admixtures were used for the concreting works. The tunnel was waterproofed with 3,3 million square metres of Sikaplan membranes – roughly the size of 330 soccer fields. Overall, some 40 000 t of Sika products, equivalent to 1 700 freight wagons, were transported to the site.