Vehicles for people with reduced mobility must travel on the **shoulder** when there is no road or part of it specifically designated for them. The shoulder is the area next to the roadway that is not used by most vehicles.

In contrast, **automobiles**, such as cars with trailers, should not travel on the shoulder unless there is a breakdown or another unforeseen situation. Additionally, in situations of heavy traffic, no vehicle is allowed to travel on the shoulder. Therefore, vehicles for people with reduced mobility are an exception and must use the shoulder in the absence of a specific road for them.