On September 27, the Baise–Napo–Pingmeng Expressway (Napo to Pingmeng Port Section) project in Guangxi, known as the "Naping Expressway," reached a major milestone as the Pingmeng Border Pass Tunnel achieved full-bore breakthrough, marking a significant step toward the expressway's opening to traffic.

　　Invested in and constructed by Guangxi Xinfazhan Group, a directly affiliated enterprise of Guangxi Beibu Gulf Investment Group Co., Ltd., and built by Guangxi Road Construction Group, the Naping Expressway is an important component of the New Western Land-Sea Corridor and a key part of the major international corridor facing ASEAN. The main line is 51.093 km long, built to a two-way four-lane expressway standard with a design speed of 100 km/h.

Aerial view of the Naping Expressway main line.

　　The Pingmeng Border Pass Tunnel is a key controlling project of the Naping Expressway. Designed as a separated tunnel, it has a left tube 4,790 meters long and a right tube 4,810 meters long, making it the longest and most difficult tunnel on the entire line.

　　The Pingmeng Border Pass Tunnel faces complex geological conditions and construction organization challenges. The construction area passes beneath a national highway and is adjacent to residential areas, while fractured surrounding rock and strongly developed groundwater present a series of difficulties for the project team. Faced with such a construction environment, the team adhered to the environmental construction principle of "less damage, more protection, less disturbance, more prevention" and innovatively adopted the "zero-excavation" portal construction method using a special-shaped arch for tunnels in oblique terrain, reducing damage to natural vegetation from tunnel construction.

　　To overcome the complex geological conditions, the construction team introduced cutting-edge technologies such as airborne geophysical prospecting and intelligent surrounding rock identification, providing accurate data support for advanced geological forecasting of the tunnel and effectively reducing construction risks.

Green construction at the entrance of the Pingmeng Border Pass Tunnel, blending with the surrounding environment.

　　The conversion rate of scientific and technological innovation achievements at the Pingmeng Border Pass Tunnel reached 85.7%. The construction team independently developed an automatic split feeding device for the secondary lining trolley, greatly improving feeding efficiency and effectively enhancing the appearance quality of the tunnel's secondary lining; it also innovatively developed a new cooling device for extra-long tunnels, effectively solving the problem of high-temperature construction inside the tunnel and safeguarding the health of tunnel workers.

　　As of now, 78% of the pavement works, 58% of the traffic safety works, and 85% of the building works on the Naping Expressway have been completed. The full-bore breakthrough of the Pingmeng Border Pass Tunnel provides more working faces for the Naping Expressway to accelerate asphalt pavement paving and the construction of ancillary works such as traffic safety and electromechanical systems.