Recently, the world's longest spiral tunnel, the Hankou Tunnel on the Xinxiang-Jincheng Expressway (Xinjin Expressway), built by the China State Construction Engineering Corporation (CSCEC)'s subsidiary China Construction Communications Engineering Group Co Ltd(CCCEG), opened to traffic, marking the full opening of the Expressway. The journey from Jincheng, Shanxi Province, to Xinxiang, Henan Province, which used to take more than three hours, will now take just over an hour.
Located at the junction of Henan and Shanxi provinces, the Xinjin Expressway connects Xinxiang and Jincheng, and winds through the interior of the Taihang Mountains, forming a 28-kilometer spiral tunnel system. Among a total of nine tunnels (from Wangmangling Tunnel in Lingchuan County, at an altitude of 1,280 meters, to Magou Tunnel in Xinxiang City, at an altitude of 500 meters), the Hankou Tunnel, built by CSCEC Road and Bridge Group Co Ltd, is currently the world's longest spiral tunnel.
The elevation of the Hankou Tunnel ranges from 784 to 893 meters, with a maximum relative height difference of 109.34 meters between the entrance and exit. The left line is 4,457 meters long, and the right line is 4,366 meters long, making it longer than the current Guinness World Record holder - the Jinjiazhuang Spiral Tunnel of the Yanchong Expressway (with the left line being 4,128 meters long and the right line being 4,104 meters long).
As the slope would have been too steep if the tunnel were to be built in a straight line, it was built into a spiral shape. The minimum radius of the internal curve was only 700 meters, which not only posed a risk of hypoxia but also made it prone to deviation. Builders had to construct the tunnel on almost vertical cliffs, which made it difficult to transport materials and water. The tunnel is also surrounded by thin-layered sandstone, meaning that throughout the building process, it was subject to collapse and landslides.
Faced with difficulties and challenges, the project team innovatively applied high-tech tools rarely used in tunnel engineering, such as "BIM+" (Building Information Modeling) technology, and finished the building in just two and a half years.
According to reports, the full opening of the Expressway will greatly promote economic and cultural exchanges between Henan and Shanxi provinces, and play an important role in improving the transportation of the coal and cultural and tourism industries of the two provinces, as well as the development of old areas in the Taihang Mountains. It also has significant implications for the implementation of the Yellow River ecological and economic belt strategy.
(Executive editor: Xie Yunxiao)
