On May 4, the left tube of the Rongli Tunnel on the Nandan-Tian'e-Xialao Expressway in Guangxi was successfully holed through.

The Rongli Tunnel is located in Dangyang Village, Yanlai Township, Tian'e County, Hechi City. It is a key passage connecting Leye County and Tian'e County. The left tube is 1,172 meters long and the right tube is 1,230 meters long, with a maximum burial depth of 199 meters. It is a separated long tunnel crossing a mountain ridge. The actual surrounding rock of the tunnel deviates considerably from the designed surrounding rock, and the structural stability is poor, making it highly prone to disasters such as large deformation of soft rock and rockbursts. At the same time, the tunnel site area is close to a provincial road, with high-voltage power lines crisscrossing, many curves and steep slopes, and great difficulties in power supply and material transportation. The project is characterized by high construction difficulty, numerous interference factors, and high safety risks.

During construction, builders from the CCCC First Highway Engineering Group Co., Ltd. carried out regular geological sketching of the tunnel face, optimized support parameters and support schemes, introduced advanced equipment such as multifunctional geological drilling rigs, and made every effort to coordinate machinery transportation, material organization, and power supply, ensuring the smooth and rapid progress of the tunnel.

The main line of the Nantian Expressway is about 105 kilometers long. It is the project under construction in Guangxi with the highest bridge-tunnel ratio, the largest bridge span, and the longest single-tube tunnel. After completion and opening to traffic, it will end the history of Tian'e County having no expressway access.