The Ya’an-Lugu section of Ya’an-Xichang Expressway in Sichuan Province, 46 km long, was finally completed in 2012. It is a demonstration project typically marked by “survey and design model” and “science and technology demonstration” determined by the Ministry of Transport, known as “Chinese Highway Bridge and Tunnel Museum”, “Space Ladder Expressway” and “Expressway in the Clouds”, for which the world's first double helix tunnel was built.