At 13:30 on September 5, at the construction site of the No. 2 Grand Bridge of the Harbin-Yichun High-Speed Railway in Cuiluan District, Yichun City, an A3-type bridge erection machine smoothly and precisely placed the final 715-tonne, 32-meter box girder at its designated position, marking the completion of all girder erection work for the Tieli-Yichun advance section of the Harbin-Yichun High-Speed Railway project and laying the foundation for track laying along the entire line.

The Harbin-Yichun High-Speed Railway is an extension of the Beijing-Harbin–Beijing-Hong Kong-Macao corridor within China's "Eight Vertical and Eight Horizontal" high-speed rail network. It starts in Harbin, Heilongjiang Province, passes through Suihua City, and ends in Yichun City, with a total mainline length of 299 kilometers and a design speed of 250 kilometers per hour. The line has nine stations: Harbin, Harbin North, Hulan North, Xinglongzhen West, Suihua South, Qing'an South, Tieli, Riyuexia, and Yichun West.

According to Yang Xushu, project manager of the Tieli-Yichun Railway advance project of China Railway 22nd Bureau Group, the Harbin-Yichun High-Speed Railway consists of the Harbin-Tieli section and the Tieli-Yichun section. The Tieli-Yichun advance project began construction in 2021 and is located at the southern foot of the Lesser Khingan Mountains, the highest-latitude area in China. The route passes through many mountains and scenic areas, and the lowest annual temperature in the construction area along the line can reach minus 40 degrees Celsius. It is the northernmost high-speed railway under construction in China and the country's first high-speed railway to cross permafrost regions. Along the route are 14 island-shaped permafrost zones, including ice-rich permafrost, ice-moderate permafrost, ice-saturated permafrost, and ice layers containing soil, with a maximum frozen depth of 7 meters. The railway will also cross nearly 50 kilometers of primeval forest, a Class II water source protection area, and scenic areas such as the Riyuexia National Forest Park.

Construction site of the Harbin-Yichun High-Speed Railway advance project

"Because the geological structure along the route is complex, with multiple seasonal frozen soil frost-heave zones that are highly sensitive and poorly stable, temperature changes can easily cause thaw settlement, bringing great difficulty to construction. During construction, we organized and prepared various special construction plans around key and difficult projects, carried out professional training for technical personnel, held expert review meetings, and conducted joint research on site. At the same time, we overcame many technical 'hard bones,' including soft soil subgrades and frozen soil subgrades, set multiple records in techniques and construction methods, accumulated valuable experience for building high-speed railways in permafrost regions in China, and filled multiple technical gaps. In particular, for the box girder prefabrication and erection works, the section involved 389 girders for fabrication and erection; low temperatures and a short effective construction period were the main constraints. We overcame various adverse effects and completed the box girder prefabrication and erection task, which is a milestone node of the advance project. In perennially frozen soil, we used the 'cross' positioning method for the first time to precisely position pile foundations, and adopted bored piles for fixation and casing installation to drive piles in frozen soil, achieving a 100 percent pile formation rate. We innovatively developed the patented construction method of a 'double-layer casing structure for bored pile construction in frozen soil sections,' enabling the use of an ultra-long double-layer steel casing technique to construct pile foundations in frozen soil sections. This avoids the loss and interconnection of pile foundation concrete caused by thawing permafrost, failure of pile foundation strength to meet design standards due to excessively low temperatures, and damage to the original geological environment, effectively solving engineering quality problems in frozen soil layers," said Fan Chunyu, deputy manager of the Tieli-Yichun Railway advance project of China Railway 22nd Bureau.

Panoramic view of construction of the Harbin-Yichun High-Speed Railway advance project

The Harbin-Yichun High-Speed Railway is an important transportation infrastructure project for actively integrating into the national Belt and Road Initiative, deeply implementing the new round of the strategy for revitalizing the old industrial base in Northeast China, and connecting with the China-Mongolia-Russia Economic Corridor. Once the project is completed, travel time between Harbin and Yichun by rail will be shortened from about 7 hours to less than 2 hours, further extending northward and improving the 2-hour and 3-hour traffic circles centered on Harbin. It will further improve the high-speed railway network in Northeast China, accelerate the development of the regional tourism industry, speed up industrial clustering, personnel exchanges, and foreign trade cooperation between China's northern border regions and developed inland areas, create a new engine for regional economic growth, and provide support for revitalizing the economy of Heilongjiang and comprehensively building a modernized new Heilongjiang.