ZHENGZHOU, March 4 (Xinhua) -- Construction on China's first large-span steel truss bridge with ballastless tracks has entered the key stage of erection in Zhengzhou, capital of central China's Henan Province.

The first 57-tonne transversal spacing component was precisely descended on top of the largest bridge pier on Sunday.

The 4,377-meter-long Zhengzhou Yellow River extra large bridge, built by the China Railway Major Bridge Engineering Group, is the key part of a high-speed railway connecting Zhengzhou with Jinan, capital of the eastern Shandong Province. The railway is designed to allow a speed of 350 km per hour.

With its steel beams weighing more than 70,000 tonnes, the bridge is designed with two floors. The upper floor is a six-lane expressway while the lower level is a four-track railway.

Compared to traditional tracks, the ballastless track has a longer life span and requires less effort in maintenance.

Conquering the challenges of environmental protection and hydrological conditions of the Yellow River and high standards on building technology, the construction of the bridge will set up a model for China's large-span steel truss bridge to be laid with ballastless tracks, said Chen Erbin, an official in charge of the project.

Upon completion of the Zhengzhou-Jinan railway, transport time between the two cities will be cut from five hours to within two hours.