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SIYUAN enjoys competitive technological strength in survey & design of complex mountain area railways, and have undertaken a number of large-scale mountain railway projects including Xiangtang-Putian Railway and Yichang-Wanzhou Railway. Particularly, the Yichang-Wanzhou Railway completed and open to traffic in 2010, with 70% of the railway line located in karst areas and 74% in the form of bridges and tunnels, is currently a mountain railway with the most complicated geology, the most difficult terrains, and the most risky construction conditions in China. Its geological conditions are rarely seen even around the world. Therefore, It’s called “forbidden zone of road construction”, and is acknowledged as a milestone in the history of complex mountain railway construction in China.