57 km long Gotthard Base Tunnel beneath the Alps between Erstfeld and Amsteg in Switzerland is the longest tunnel in the world meant for passenger or goods transportation. The rail tunnel, drilling of which has already been completed, is expected to be complete in all respect and open for traffic in 2017. This civil engineering marvel would shorten the journey time between Zurich and Milan by over one hour besides enabling high volume of transport at faster speed.
The project cost is estimated at little over $10 billion. The tunnel, piercing the Swiss Alps, would enable running of around 300 trains each day at speed of up to 250 km per hour.
This tunnel breaks the earlier world record held by 53.8 km long Seikan rail tunnel between two islands in Japan. Actually, the world record for the longest tunnel of any kind is still held by the approx. 136 km long Delaware Aquaduct that transports water to New York City, USA.