After 375 days, on September 16, the Zhangjiayuan Tunnel of the Yin-Kun Expressway, the largest single-investment expressway project in Ningxia invested and constructed by China Railway Construction Investment Group and undertaken by China Railway Construction Bridge Engineering Bureau Group, was successfully holed through.

The Zhangjiayuan Tunnel is located in Zhangjiayuan Township, Tongxin County, Wuzhong City, in a loess ridge and hill landform area. It is a typical collapsible loess region, with a total length of 772 meters and a maximum burial depth of 102 meters. It was constructed from both the entrance and exit, and is a separated medium-length tunnel. As the first tunnel on the entire Yin-Kun Expressway to be holed through, it has laid the foundation for the entire line to be completed and opened to traffic in 2024.

Tan Ruifeng, technical director of the China Railway Construction Bridge Engineering Bureau Group's Yin-Kun Expressway Section 7 project: "The tunnel is located in a collapsible loess section, and the entire line consists of Class V surrounding rock, which is prone to small-scale collapse. For this reason, during construction we adopted the three-bench seven-step excavation method and strictly applied measures such as advanced pipe forepoling, strict grouting, short advance, strong support, and frequent measurement, effectively ensuring construction safety and quality."

The Taiyangshan Development Zone to Pengyang (Ningxia-Gansu border) project of the Yinchuan-Kunming Expressway (G85) is an important section within Ningxia under the National Highway Network Plan (2013-2020), and also an important part of the "Fifth Ray" in Ningxia's "Three Rings, Eight Rays, Nine Links" expressway network plan. Once completed, the project will become a new major north-south transportation artery in Ningxia, effectively improving the transportation network conditions in the central and southern areas of Ningxia.