Under what circumstance is making a U-turn illegal?

Making a U-turn is considered illegal when it is not clear or prohibited by a sign because safety and visibility are key concerns for this type of maneuver. A U-turn requires ample space and a clear line of sight to ensure that other vehicles and pedestrians can be seen. If the area is blocked or if a sign explicitly prohibits U-turns, attempting to make one could create hazardous conditions, increasing the risk of accidents.

In contrast, heavy traffic may make U-turns difficult but does not inherently make them illegal unless specified by traffic laws or signage. Similarly, the legality of U-turns is not confined to residential neighborhoods, nor is it restricted to daylight hours. Thus, the presence of clear visibility and the lack of prohibitory signs are critical factors in determining whether a U-turn can be performed legally.