How to divide taxis in Luoyang?

Taxi drivers are generally divided into two categories, one is day shift and the other is night shift. Each class works 12 hours, and the two classes add up to exactly 24 hours. How to distinguish between day shift and night shift for the purpose of making money? It is subject to sunrise and sunset, usually at 6 o'clock in the morning and 6 o'clock in the evening, all year round.