The Spring Festival holiday in China is often described as the largest human migration on Earth, as millions of people return to their hometowns to reunite with their families and celebrate together. However, for high-speed train drivers like Yu Longnian and Liu Jingya, there are no reunions, and instead Spring Festival is the time when they are at their busiest.

This year's Spring Festival travel rush began on Jan 26, and serves as a test of the nation's critical infrastructure, such as railways, to ensure that people can return home smoothly and on time.

For Yu, 35, and Liu, 36, Spring Festival is a time of sacrifice.

"I know that if I have a big dinner at home on Spring Festival Eve, I must be working the next day," Yu said.

"Though I am not home, I feel a great sense of achievement in helping others get home for their reunions," Liu said.

The experienced drivers are able to operate over 20 types of high-speed trains, providing flexibility for their employer China Railway Wuhan Group, and meaning they can work a variety of routes across the country.

Having joined the company in 2009, both drivers have transitioned from operating freight trains at 120 kilometers per hour to high-speed trains reaching 350 km/h.

"Thanks to the development of China's high-speed railway network, more types of high-speed trains have been introduced. I am lucky to be part of it and to be able to drive the different types of trains," Yu said.

Yu, who leads a team of the company's top high-speed train drivers, is proud of being able to drive different types of high-speed trains.

"A good driver has to find the patterns and uncover the similarities and differences in operation," he said.

For new drivers, in order to be able to operate a new model on a new route, he or she has to ride along with an experienced driver to get familiar with the train and route.

The new driver then goes on to take the controls under the supervision of an experienced driver.

"It's to ensure safety," Yu said.

Liu said the operation of high-speed trains has become simpler over the years.

"Fuxing is a more advanced train with a better man-machine interface. It is also more stable and greener," he said.