Since its official launch in December 2012, China's first high-speed rail line that operates in regions with extremely low temperatures, as low as -40 C, has been undergoing monitoring to see how it copes - and it is coping well.

The 921-km line with 23 stops, links Harbin, capital of China's northernmost province of Heilongjiang, and the port city of Dalian, in Liaoning province.

The line operates two different schedules: The winter schedule, from December to April, sees trains running at a top speed of 200 km/h; the summer schedule operates during the rest of the year when trains reach 300 km/h.

Ticket prices depend on the schedules. Under the summer schedule, a ticket for a first-class seat on a train from Harbin to Dalian costs 645.5 yuan ($105) and a second-class seat costs 403.5 yuan, while winter schedule tickets cost 454.5 yuan for a first-class seat and 283.5 yuan for a second-class seat.

The line cuts the traveling time between the two cities from nine hours to about three-and-a-half hours.

Zhang Yuhao, 33, took up a teaching position in Dalian after graduating from university in Harbin in 2006.

"My hometown is Zhaodong, a county 53 km from Harbin. In the past, I had to spend nine hours on the train every time I came back home, and it was difficult to buy a ticket, especially during holidays," said Zhang. "Since the opening of the Harbin-Dalian high-speed rail line, the trip has become much easier. Even in summer, I can bring fresh seafood to my parents from Dalian. It was unimaginable before."

"The high-speed rail line really changed things a lot," said Liu Zhaoji, a conductor on the line. "The passengers marvel at the speed and stability during the journey. For us, the line provides a much better working environment due to the trains being designed to a high standard, and the work hours are much more comfortable because the trains all run during the daytime.

"Since Feb 4, the first day of this year's Spring Festival travel peak, trains on the Harbin-Dalian high-speed link have been almost full every day, substantially easing the transport burden in regions along the line."