HARBIN, Jan. 16 (Xinhua) -- Work on a railway tunnel to operate in a region with temperatures as low as minus 35 degrees Celsius was completed Tuesday in northeast China's Heilongjiang Province, according to the operator.

The tunnel, named Aimin, is the last tunnel on the 293-km Harbin-Mudanjiang high-speed rail line, which has speeds of up to 250 kph, according to China Railway Construction Corporation.

"Builders have overcome many difficulties such as construction in freezing weather or heavy snow. The Aimin tunnel has laid the foundation for the full operation of the Harbin-Mudanjiang line by the end of 2018," said Li Baocheng, an employee with the company.

China's railway network reached 124,000 km and handled 2,595 high-speed trains by the end of 2016, making up 60 percent high-speed trains worldwide.