What should be observed in relation to route planning?

Your answer included all the essential elements relevant to route planning under German traffic regulations.

1. The German summer holiday traffic regulations address increased traffic during peak vacation times, which can affect route choices.
2. Regulations regarding driving and rest periods are crucial for ensuring drivers do not become fatigued, maintaining safety on the roads.
3. Awareness of potential traffic obstructions due to roadworks helps in planning a more efficient route, reducing delays.

This combination is necessary because neglecting even one of these factors can lead to unsafe driving conditions or delays, which is why observing all three points is vital for safe and effective journey planning in Germany.