But due to the pressure of their jobs, the two captains are just nodding acquaintances, and they do not even know each other's name.

The retirement age for these icebreakers is 55. And this year marks the last Spring Festival on the job not only for Wang Jianhua, but also for Li Huanqun.

The two captains have much in common as well as a common unique skill: Just by looking at the temperature and wind direction, they know how much ice they will encounter, and how many hours they need to get it off.

Besides, they both have common concerns - they both are reluctant to leave their team members, and they worry about their safety all the time.

But, despite their hard work there is satisfaction.

"Every time I remove the ice, and I watch the trains go through the tunnel, I see the passengers warm and safe," says Wang Jianhua.

After nearly two hours of heavy work in the dark tunnel, the icebreaking teams leave the tunnel.

With ladders on their shoulders, the men in orange uniforms make their way back to base.