The world’s longest and deepest rail tunnel opens officially today in Switzerland aiming to change completely the European freight transport.

After almost two decades of construction work, the Gotthard base tunnel measuring 57km (35-mile) in length and situated 2.3km deep under the Alps will provide a high-speed rail link under the Swiss Alps between northern and southern Europe.

German Chancellor Angela Merkel, French President Francois Hollande and Italy’s Prime Minister Matteo Renzi will attend the grand opening of the tunnel, which will be mainly used for further test journeys until commencing regular service in December 2016, as the Guardian reports.

When full services begin, travel time between Zurich and Milan will be reduced by an hour to two hours and 40 minutes, while about 260 freight trains and 65 passenger trains will pass through the tunnel in as little as 17 minutes, as BBC says.

The new Gotthard base tunnel, which has been in planning since the 1980s, will bypass the old Gotthardbahn rail tunnel, and run on a flat low-level route, the first of its kind in the Alps.

The project, which cost €11bn to build, is being financed by value-added and fuel taxes, road charges on heavy vehicles and state loans that are due to be repaid within a decade.