Recently, the Pa'erba Tunnel, a key node of the Sichuan S220 reconstruction highway project, was successfully holed through, marking important progress on the project. The tunnel is the longest on the entire route and one of the most challenging sections of the works.

The S220 reconstruction highway project is being built with the participation of CCCC Second Harbor Engineering Co., Ltd., a central state-owned enterprise based in Wuhan. It is located in the reservoir area of the Shuangjiangkou Hydropower Station on the Dadu River in Sichuan (the Muerzha to Rejiao section). As an ancillary project of the Shuangjiangkou Hydropower Station, it is about 38 km long and serves as an important north-south transport artery in Aba Prefecture. Section IV, about 10 km long, lies in a deep V-shaped gorge with a harsh construction environment and difficult conditions, and is the controlling section of the entire route.

The Pa'erba Tunnel is 2,980 meters long and is a single-tube, two-way tunnel. The tunnel passes through complex geological conditions with large topographic relief, broken rock strata and serious fissure water inflow, making construction extremely difficult. To ensure construction safety and quality, the project team followed the principles of "advance pipe forepoling, strict grouting, short excavation, strong support, early closure, frequent measurement, rapid feedback and settlement control," and adopted a number of scientific measures to address the challenges.

With the breakthrough of the Pa'erba Tunnel, all five tunnels on the project have now been holed through, opening up new prospects for the project's construction and contributing to high-quality development on the snowy plateau.

The smooth breakthrough of the tunnel will have a significant impact on the progress of the entire project. Once completed and opened to traffic, it will greatly improve transport conditions for local residents and is of great significance to the social and economic development of the Tibetan region.