When two drivers are assigned to a long-distance coach, what is the mandatory shift rotation protocol to prevent fatigue?

1. Drivers must alternate driving shifts before reaching the continuous driving time limit (max 4 hours day / 2 hours night) and record driver changes in the dynamic monitoring terminal
2. One driver drives the entire 8 hours while the other driver sleeps at the back, then they swap for the return journey
3. Drivers may only swap seats while the vehicle is cruising at 80 km/h on the highway
4. Both drivers must hold the steering wheel simultaneously