Maybe that's because it's also one of the world's steepest roads, chiseled into the mountain by local villagers. The Guoliang Tunnel is located in the Taihang Mountains in China's Henan Province ...

The tunnel goes through Gauley Mountain between Ansted and Gauley Bridge ... The silica dust would often be so thick in the air that the workers could only see a few feet ahead inside the tunnel ...

rehabilitate and upgrade the 19-mile-long Mountain Tunnel, a key component of the Hetch Hetchy Water System that takes water from Tuolumne County and sends it to San Francisco. The San Francisco ...