Swiss engineers completed the world's largest tunnel Friday, drilling through the last few feet of rock needed to complete the 35.4-mile tunnel underneath the Swiss Alps, the Associated Press reported.

The Gotthard Base Tunnel, as it is called, was undertaken in order to create a passage for a high-speed transportation system through the Swiss Alps. The tunnel now trumps Japan's Seikan Tunnel, a 33.5-mile tunnel that was formerly the world's longest.

The project has been under way for almost 20 years and about 2,500 workers have been a part of it. The railroad being built in the tunnel is expected to be open to trains by 2017.

The project cost $10 billion – or $1,300 per Swiss voter – a cost they agreed to foot in a referendum more than 20 years ago. The completion of the tunnel was greeted with elation across the country.

Millions of tons of goods are now transported through that section of the Alps on heavy trucks, which are slower and damage the fragile mountain environment. The rail will be more faster and have less of an impact on the environment.

Two other high-speed rail systems through the Alps are planned, but are far from completion.

IN PICTURES: World's longest tunnel