One of Chinas hardest tunnel projects completed after 12 years

The Dazhu Mountain Railway Tunnel, dubbed as one of China s hardest tunnel projects, was completed on Tuesday after 12 years of work. The tunnel is a key part of a railway that connects Dali City and Ruili City in southwest China s Yunnan Province. Subscribe to us on YouTube: Download our APP on Apple Store (iOS): Download our APP on Google Play (Android):