QINGDAO, Jan. 21 -- An eastern Chinese city has offered free services to escort the children of migrant workers home as the world's largest annual human migration began ahead of the Chinese Lunar New Year.

The bus station in the city of Qingdao, Shandong Province, said non-local parents could apply for the "children mail" service if they are too busy before the festival to attend to children who have already begun their winter vacation from school.

Some parents opt to send their children to their hometowns in advance so they can be with other family members back home, and the new service allows the children to travel under the care of bus drivers and stewards, said Jiang Shiqun, Party secretary of the bus station.

Staff on the bus will exchange "codes" with the relatives waiting to pick up the children to ensure they don't end up in the wrong hands. Bus station staff will also keep an eye on the minor passengers via bus surveillance video, Jiang said.

Tan Hongwei, a seafood shop assistant who applied for the service at the Qingdao station, hoped to send his 12-year-old son to their home in Jinan City.

"The month before the Lunar New Year is usually a busy time for us. In the past, my son had to stay home and had nobody cooking for him or taking care of him," Tan said.

The service covers 14 long-distance bus lines in the province, and the station has safely transported 12 children so far this year.

Every year, legions of students and migrant workers make the journey home for China's Lunar New Year, the most important holiday for family reunions, which falls on Jan. 31 this year. During the holiday period, the country's road and railway systems are strained by a sudden surge in traffic.