China, the world's most populated country, on Friday ushered in its largest annual migration, 15 days ahead of the Spring Festival, or the Lunar New Year.

There will be three billion trips during the travel rush from Jan. 10 to Feb. 18 for family reunions, slightly up from that of last year, according to a forecast from the National Development and Reform Commission (NDRC).

NDRC predicted an 8-percent growth in train trips, 8.4-percent increase in air trips and 9.6-percent hike in waterway trips.

The 40-day travel rush is known as chunyun in Chinese. The Lunar New Year falls on Jan. 25 this year, earlier than previous years, which brings a bigger challenge to the transport system as the return trips of college students overlap with the travel rush.

Over 300 million train tickets have been sold for the Spring Festival travel rush after the presale started on Dec. 12, 2019, said China's railway operator.