China completed on Monday the construction of the world's longest expressway tunnel through snow-covered mountains in the Xinjiang Uygur autonomous region, marking a significant milestone in its infrastructure development.

Once operational, the 22.13-kilometer Tianshan Shengli Tunnel will reduce the travel time through the Tianshan Mountains — one of the longest mountain ranges in the world — from three hours to about 20 minutes.

It will significantly boost connectivity between northern and southern Xinjiang and help the region, which is a core area on the Silk Road Economic Belt, further open up to Eurasian countries, the regional government said.

As a crucial section of the 319.72-km Urumqi-Yuli Expressway, which runs from the regional capital of Urumqi in northern Xinjiang to Yuli county in southern Xinjiang, the tunnel will reduce the driving time between the two locations from about seven hours to just over three hours. The expressway is expected to open to traffic in 2025.

The tunneling work started in April 2020. The construction team had to overcome many difficulties and continuously innovate to beat challenges such as an average construction elevation of over 3,000 meters and complicated geological conditions.

With the construction site located close to the Tianshan No 1 Glacier and the Urumqi water source protection area, the team was also required to maintain exceptionally high ecological protection standards.

The team adopted the construction pattern of three drifts and four shafts, according to China Communications Construction Xinjiang Transportation Investment and Development Co, which built the tunnel.

Two specially designed tunnel boring machines were used to build the middle drift and create a working platform for further tunneling, the company said.

This is the first time that a tunnel boring machine was used to construct a road tunnel in China, marking a major technological breakthrough. The use of new technologies helped reduce the construction time from 10 years to just over four years, the company added.

Yang Dongdong, a member of the construction team, said they successfully dealt with many incidents, including wall collapses and gushing water. "I feel very emotional to see the tunneling work is finally over. It's like seeing my child being born," he said.

Cui Jingchuan, president of China Communications Construction Xinjiang Transportation Investment and Development Co, said that all of the machinery used to tackle the unprecedented challenges was domestically developed.

"We have broken the technological monopoly of foreign countries in this field and taken the lead in innovation," Cui added.

The regional government said the new tunnel will boost the flow and communication of people between northern and southern Xinjiang, allowing for more career and development opportunities.

Contact the writers at cuijia@chinadaily.com.cn