What can red-white warning plates on vehicles indicate?

Red-white warning plates on vehicles serve important functions in road safety according to German traffic regulations. Specifically, they indicate that a vehicle poses certain hazards to other road users.

1. A trailer parked on the roadway within a built-up area is indicated to warn other drivers of potential obstructions in the path, helping to prevent accidents.

2. A vehicle with excessive width is also marked to alert drivers about its dimensions, which could affect passing maneuvers and require caution.

Both indications are essential for maintaining safe driving conditions. However, a vehicle transporting dangerous goods is not indicated by red-white warning plates, which is why that option was not included in the correct answer. Understanding these warning signs helps ensure safety and compliance with road rules. It's important to recognize all applicable warnings to avoid accidents and enhance overall road safety.