BEIJING - China has acted to ensure travelers a safe trip during the May Day holiday starting Wednesday.

The Ministry of Public Security has warned the public of the risks including peak flows on expressways and around tourist sites, heavy rainfall, and more traffic violations.

Police have been drafted to secure major transportation hubs such as key railway stations and trains.

Tighter security checks are required with more personnel and facilities involved and patrol has become more frequent, especially in densely populated areas, railway police authorities say.

Plainclothes police have been sent to major train stations and on board to crack down law violations, including theft and fraud. Random inspections of suspicious luggage or items will also be made on trains bound for cities including Beijing and Shanghai.

More police will be arranged to watch and prevent potential safety hazards from natural conditions, such as heavy rainfall and geological disasters, according to railway police authorities.

Ctrip, China's largest online travel agency, estimated that about 160 million trips will be made during this year's four-day May Day holiday.