On May 13, 2026, the exit end of the Rishipuji Tunnel on the Zhaopu Expressway officially entered the tunnel for construction. This 5.25-kilometer-long spiral tunnel has entered the main construction phase and will break the world record for the longest highway spiral tunnel after completion, becoming another landmark project for Sichuan to overcome the complex geological problems in the Hengduan Mountains.

The Rishi Puji Tunnel is located in Puge County, Liangshan Prefecture, and is the core of the control engineering cluster of four tunnels, one bridge, and two interchanges on the Zhaopu Expressway. The tunnel passes through the eroded Zhongshan landform area of the Hengduan Mountains and crosses the Luxi River channel, with a height difference of 126 meters between the inlet and outlet. It needs to face multiple world-class geological challenges such as gas, faults, karst, and high-pressure water inflow. Among them, the difficulty of waterproofing, drainage, and safety control in the section with rich water fissures is the highest along the entire line. This is another major breakthrough in the construction of spiral tunnels in mountainous areas in Sichuan, following the Ganhaizi Double Spiral Tunnel on the Yaxi Expressway and the Laoyingpan No.1 Tunnel on the Xizhao Expressway.

Cracking the problem of high-pressure water influx

Faced with the obstacle of high-pressure water influx, the project team innovatively created a closed-loop water control+graded drainage combination process system. By using a high-precision advanced geological prediction system to install perspective eyes for excavation, advanced curtain grouting is implemented according to the closed-loop process of water exploration design grouting evaluation, and a circular water stop wall is built inside the surrounding rock; At the same time, abandoning the traditional one pump to the bottom mode and setting up multi-level drainage pump stations to form a relay drainage system not only reduces construction risks but also significantly saves energy consumption. The tunnel also adopts intelligent designs such as non powered automatic water replenishment for fire water tanks and emergency traffic transfer belts, striving to create a century old safe project.

82% Bridge Tunnel Ratio

The Zhaopu Expressway starts from Sikai Town, Zhaojue County and ends at Huashan Town, Puge County. It has a newly built mileage of 75.7 kilometers, with four lanes in both directions and a designed speed of 80 kilometers per hour. The bridge tunnel ratio is as high as 82%, and the construction period is 5 years. Keywords: transportation, highways

As an important part of the Chengdu to Yunnan expressway network in Sichuan Province, the project will end the history of Butuo County not being connected to highways after completion, directly benefiting over 600000 people along the route. By the end of 2025, the mileage of highways in Sichuan has exceeded 10000 kilometers, and the Zhaopu Expressway is the most challenging part of this road network.Editor/Cheng Liting