The world's largest annual human migration, or the Spring Festival travel rush, which will come to an end on Friday, is expected to record a total of over 400 million passenger trips by rail, according to the national railway operator.

The China Railway Corporation said some 9.8 million passenger trips are expected to be made by rail on Friday, which saw a 10 percent year-on-year increase.

The annual travel rush, which is also known as chunyun, often tests the limits of the country's transportation system.

This year's travel rush began on Jan 21, with railway trips expected to hit 413 million in total, according to the National Development and Reform Commission.