Recently, the right tube of the Caoguoshan extra-long tunnel on the Manjin Expressway, invested in and constructed by Yunnan Construction and Investment Holding Group, was successfully holed through, setting a new record for the length of tunnels holed through on the group's expressways and laying a solid foundation for the Manjin Expressway to achieve its year-end completion and opening target. On September 23, the right tube of the Shanglagu Tunnel on the Yongda Expressway, also invested in and constructed by Yunnan Construction and Investment Holding Group, was successfully holed through. With this, both tubes of the Shanglagu Tunnel have been fully holed through, marking an important step by the Yongda Expressway toward its goal of full-line opening to traffic.

As a key project of Yunnan Province's "Access to All, Connectivity for All" program, the Manjin Expressway has a main line length of 50.58 km, with 127 bridges and 16 tunnels along the entire route, and a bridge-to-tunnel ratio of 79.8%. As a key controlling project of the entire line, the Caoguoshan Tunnel connects Adebo Township and Jinhe Town in Jinping County, Honghe Prefecture. It is 7,005 m long with a maximum burial depth of 903.8 m, and features complex engineering geological conditions and great construction difficulty. Since construction began in December 2017, the project has consistently followed the "four guarantees, one control and one cultivation" project management requirements, advancing construction with high quality and efficiency. Together with Southwest Jiaotong University, it carried out the "Research on Key Technologies for Rockburst Prediction and Prevention and Control in the Caoguoshan Tunnel," introduced the domestically advanced three-boom tunnel drilling jumbo, and strictly followed the working approach of "advance prediction, minimal disturbance, early support, frequent measurement and short advance," ensuring that each process met design requirements and guaranteeing tunnel safety and quality. Deeply practicing the ecological and environmental protection concept that "lucid waters and lush mountains are invaluable assets," the project canceled the inclined shaft auxiliary construction method and adopted excavation from both ends, greatly reducing damage to the ecological environment and effectively protecting the natural ecosystem of Caoguoshan.

The Shanglagu Tunnel is located in Yijiu Town, Yongren County, Chuxiong Prefecture. It is designed as a separated tunnel, with a right tube length of 535 m and a left tube length of 590 m; the maximum burial depth of the tunnel is 75 m, and the left tube was holed through on September 5, 2021. The tunnel construction site features shallowly dissected low-to-medium mountain topography. The surrounding rock is mainly sandy mudstone, locally intercalated with calcareous mudstone and sandstone that are relatively soft, with water-erosion cavities of various sizes commonly seen. The engineering geological conditions are ordinary, and the interlayer bonding is weak; improper or delayed support can easily lead to crown collapse accidents. To ensure the smooth progress of the project on schedule, since the start of construction the project company has made scientific deployments and careful arrangements, joining forces with the participating units and carrying out tunnel construction strictly in accordance with the specially demonstrated construction scheme reviewed by experts and the two-stage construction drawing design. During construction, the project company strictly implemented tunnel construction requirements, comprehensively analyzed and assessed various forecast conditions, and formulated corresponding construction schemes based on actual data, greatly reducing construction risks under complex geological conditions.