Linemen from Harbin Railway Bureau check the track by using professional equipments in Harbin, northeast China's Heilongjiang Province on Jan. 12, 2017. The lowest temperature in Harbin dropped to minus 20 degrees Celsius on Thursday. As cold weather might cause subtle physical impact on Harbin-Dalian high-speed railway, workers have to examine the railway track equipment between 0:30 a.m. and 4:30 a.m. to ensure smooth operation. (Xinhua/Wang Kai)
