China's transportation networks are bracing for over 310 million cross-regional passenger trips on January 31, the 18th day of the 40-day-long Spring Festival travel rush, which began on January 14.

Known as "chunyun" in Chinese, this travel period is often described as the world's largest human migration. During these 40 days surrounding the Chinese New Year holiday, or the Spring Festival, hundreds of millions of people traverse the country for family reunions or sightseeing, all in celebration of China's most important holiday.