Railway transportation industry: during the Chinese New Year, the employees of the railway transportation system are the busiest. Because before and after the Spring Festival every year, there are more than 40 days of peak passenger flow in Spring Festival travel rush. This year, the number of tourists from Spring Festival travel rush reached a record 3 billion, equivalent to half of the world population movement. Therefore, Spring Festival travel rush is equivalent to a big exam once a year for employees in transportation industries such as railways, highways and civil aviation. In the face of such a big exam, the employees of the railway transportation system dare not slack off at all, and overtime has become a common thing. Moreover, there will be a wave of return passenger flow peak after the Chinese New Year, which means that every year during the Chinese New Year, employees of the railway and transportation systems have to do twice as much work as other lines.