Switzerland has opened the world’s longest and deepest railway tunnel, 17 years after starting work on the project. The Gotthard Railway Tunnel is 57 kilometers long. Trains passing through it will be about 2.3 kilometers underground at the deepest point. The tunnel cost $12 billion to build under the Alps of central Switzerland. The tunnel will reduce the time it takes trains to travel between northern and southern Europe. It is also expected to lower the number of vehicles on roads, and move cargo between north and south. Many large trucks now carry goods through Europe. The trucks pollute the air. The two-way tunnel opens for commercial service in December. When that happens, up to 260 freight trains and 65 passenger trains will be able to pass through it every day. German Chancellor Angela Merkel, French President Francois Hollande and Italian Prime Minister Matteo Renzi were at the opening ceremony on Wednesday.