Passengers board a train at Tianjin Railway Station in north China's Tianjin, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1. (Photos: Xinhua)

Passengers go through automatic ticket gates at Tianjin Railway Station in north China's Tianjin, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.

A train departs fromTianjin Railway Station in north China's Tianjin, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.

Passengers go through automatic ticket gates at Tianjin Railway Station in north China's Tianjin, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.

Passengers go through automatic ticket gates at Tongren South Railway Station in southwest China's Guizhou Province, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.

Passengers buy tickets from ticket vending machines at Tongren South Railway Station in southwest China's Guizhou Province, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.

Passengers get ready to board a train at Tongren South Railway Station in Tongren, southwest China's Guizhou Province, May 1, 2019. China's railway system saw a rise in passenger numbers as the four-day Labor Day national holiday began on May 1.