The **hazard pre-signaling device** is used to warn that a vehicle has become **immobilized** on the road. This device is a yellow signal placed at the highest point of the vehicle to be visible from afar. Its purpose is to alert other drivers about the presence of a stopped vehicle due to an emergency, a breakdown, or because the load it was carrying has fallen onto the road.


Additionally, the vehicle can use the **emergency signal**, which involves turning on all the vehicle's direction lights. This signal warns other drivers that the vehicle has a problem and may pose a danger on the road. It is mandatory for cars, trailers, and semi-trailers.

Therefore, the hazard pre-signaling device and the emergency signal work together to ensure that other drivers are aware of an immobilized vehicle, helping to prevent accidents and maintain road safety.