Why is "chunyun" rush such a hassle?

BEIJING -- Some 257.8 million Chinese passengers are expected to travel by rail during this year's "chunyun", the Spring Festival travel season.

According to the China Railway Corporation, the passenger volume during this year's 40-day spring festival travel rush will be 7.9 percent more than last year.

Chunyun is the largest annual human migration in the world. Billions of Chinese travel between their workplaces and their hometowns around the Spring Festival, which falls on January 31 this year.

Chunyun is from January 16 to February 24 this year and an additional 337 trains have been laid on to meet demand, the corporation said.