In his poem Shu Dao Nan (The Difficulty of Shu Roads), Tang Dynasty (618-907) poet Li Bai writes: "Oh, the road to Shu is as hard as the blue sky to scale!" The Shu Roads got their name from the ancient state of Shu, which once dominated today's Sichuan province, but about which relatively little else is known, due to a lack of documentation.

The builders of the expressway linking Jigzhi county in the Golog Tibetan autonomous prefecture in Qinghai province, to Barkam county, the capital of the Aba Tibetan and Qiang autonomous prefecture in Sichuan province, know how complex it is to build a road in a region with such steep terrain.

Extending for 219 kilometers, the four-lane expressway lies at an altitude above 3,300 meters. This means that the annual average temperature is just 1.4 C, and can drop as low as — 36 C. Since construction began in 2020, this extreme climate has limited work to roughly six months a year, according to the Sichuan Jiuma Expressway Company, which was responsible for the road's construction.

As the only female project manager on the site in the Aba Tibetan and Qiang autonomous prefecture, Ma Kelin says that altitude sickness has taught her a hard lesson since she joined the project in April last year.

"At first, it was nausea and vomiting, and sometimes, I could not catch my breath. It took me more than a month to get used to the altitude," she says.

For Yan Zhong, the company's deputy chief engineer, the difficulties involved in building the expressway boggle the imagination.

"The most challenging section was the 5.5-km Shenzuo tunnel, which runs through a complicated geological environment, including fragile, weak and jointed rock masses. Through consistent trial and error, we were able to come up with the final tunneling plan," Yan says, adding that the entire project depended on the tunnel being completed.

With an estimated investment of 30.2 billion yuan ($4.14 billion), the expressway is expected to open to traffic before the end of next year, according to the company.

Many of those who live along its length are waiting for the expressway to open, expecting it to contribute to economic development and growth.

To welcome tourists who may be attracted by the new road, authorities in Hongyuan county in the Aba Tibetan and Qiang autonomous prefecture have already made plans to develop a 120-hectare area with facilities for their use.