Travel boom has continued to prevail in China's highways, railway stations, airports and docks on Sunday, the fourth day of the five-day May Day holiday.

China's railway system is expected to handle 20.4 million passenger trips on Sunday, with 1,818 additional trains scheduled to cope with the growing travelers, China Railway, the country's railway operator reported, adding over 18.13 million passengers trips were handled on Saturday.

Also on Sunday, expressways across the country see a surge in return trips. Between 00:00 and 11:00, vehicles running on expressways nationwide increased by 18.6 percent compared with the same period of Saturday. Peak return flows are expected to come at 16:00 to 18:00.

On Sunday, the civil aviation is expected to handle more than 2 million passenger trips, while over 1.7 million passenger trips will be handled by waterway systems.