It's taken 17 years and cost 12.2 billion Swiss francs (about $12 billion) but Switzerland is finally ready to inaugurate the world's largest railway tunnel.

The ceremony Wednesday to celebrate the completion of the 57-kilometer (35.4 mile) tunnel through the Alps will be greeted with great fanfare with the leaders of France, Germany and Italy on hand.

The thoroughfare aims to cut travel times, ease roadway traffic and draw cargo from pollution-spewing lorries trucking between Europe's north and south. Once it opens for commercial service in December, the two-way tunnel will take up to 260 freight trains and 65 passenger trains per day.

The Gotthard Base Tunnel eclipses Japan's 53.8-kilometer Seikan Tunnel as the world's longest and burrows deeper — 2.3 kilometers (1.4 miles) — than any other rail tunnel.