The **U-turn** involves turning around to drive in the opposite direction on the same road. However, there are specific situations where making a **U-turn is prohibited** due to lack of visibility and safety.

- **Crests without visibility**: In these places, visibility is limited, preventing you from seeing if vehicles are coming from the opposite direction. This represents a significant risk of accident, as you cannot anticipate oncoming traffic.

- **Curves and adverse weather conditions**: Just like on crests, sharp curves and conditions such as fog or heavy rain reduce visibility, increasing the danger of collisions.

- **Specific prohibited places**: In addition to crests, making a U-turn is prohibited at level crossings, tunnels, highways and expressways (except in designated places), and on one-way roads.

For these reasons, on a crest without visibility, **making a U-turn is not allowed**. Safety and visibility are paramount to avoid accidents.