With the installation of the last steel box girder on Tuesday, the basic structure of a road-rail bridge over the Yangtze River in Yibin City, southwest China's Sichuan Province, is now complete. 

Under construction since early 2019, it is China's first cable-stayed bridge with a flat layout embedding both highway lanes and railway tracks. 

It features four railway tracks designed for speeds up to 300 kilometers per hour and six express lanes for cars. There are special guardrails in the middle to make sure the trains and motor vehicles do not interfere with each other.

In the final stage of closure, the most challenging part was hoisting and installing the last steel box girder.

"The last steel box girder weighs 480 tonnes. In the hoisting process, the hoisting system must maintain stable operation. The whole process took six hours. Only with the coordination of all parties, could the process be finished well," said project manager Zhang Kai.

The bridge is 1,742.1 meters long, with the main tower measuring 250 meters. It is being built to facilitate people's lives and make travel more environmentally friendly.

"We made a thorough survey of the topographic condition on both banks when designing the Yibin Lingang Yangtze River bridge. The bridge has a flat layout for both highway and railway. It will be more convenient and also more environmentally friendly for people to travel across the river," said Wang Liang, who is responsible for bridge design.

Expected to open in 2023, the bridge will shorten travel time from Chengdu, capital of Sichuan Province, to Kunming, capital of Yunnan Province, in southwestern China from about six hours to less than four hours.