Sunday is the start of the three-day Qingming Festival, or the Tomb-Sweeping Day holiday in China. Once again, the nation's transportation systems will be tested, as people travel to visit the graves of family members. Millions of people in China are expected to visit burial sites in remembrance of their deceased relatives on Tomb-Sweeping Day, which falls on this coming Tuesday. 

Railway authorities say train trips are expected to hit 12.8 million on Sunday, up by a tenth from last year. Beijing, Shanghai, Guangzhou, Shenzhen, and Kunming are among the cities that will have the biggest flow of passengers in the country.