Zhang Xiaoling may have just worked her last Spring Festival Eve in a freezing booth on the side of a major highway. Wang Keju reports.

Editor's note: Every year, China's Spring Festival travel period sees the biggest human migration on the planet. It was estimated that billions of trips would be made by road, rail, air and water during the 40-day period this year, but that was before the coronavirus outbreak. Below, our reporters profile people whose hard work helped those who managed to travel.

While millions of Chinese moved at full speed ahead on the road in order to make it home for Spring Festival Eve family reunions, Zhang Xiaoling, a toll collector in the northern province of Shanxi, spent the night alone in a small booth.

Chunyun, the Spring Festival travel rush, is the busiest time of the year for the 29-year-old toll booth operator, who collects fees from about 3,000 motorists per day during the 40-day period every year.

Having worked in the booth for seven years, Zhang knew what to expect. The job is not easy, and while her 5-square-meter station has heating and air conditioning, they have little effect because the window is always open so she can inform drivers of the toll fee, collect cash and provide change.

As soon as she sees a bank note in a driver's hand, her right hand scoops up one of her prepared piles of change. She uses two fingers of that hand to take the note and simultaneously give the change to the driver, while she prepares new piles of change with her left hand. The whole process only takes about 10 seconds.

"I have to sit on the bench for more than 12 hours and put on my best smiling face in front of drivers the whole time. After a day's work, the muscles in my cheeks are contracted," she said.