Which scenario requires using a turn signal?

Using a turn signal is essential for communicating your intentions to other drivers on the road, promoting safety and efficient traffic flow. When changing lanes or making a turn, using a turn signal is necessary to alert other road users of your intended action. This allows surrounding vehicles and pedestrians to understand your movements, helping to prevent potential accidents and enhancing the overall safety of the roadway.

In contrast, crossing a double line typically indicates a prohibited maneuver and may not require a signal, as the action itself is not legally permitted. Driving straight on a highway does not necessitate a turn signal as there is no change of direction involved. Similarly, while driving in a parking lot at low speeds may involve various maneuvers, such as parking or navigating through lanes, the use of a turn signal is not as critical as it is when changing lanes or making a turn on a standard roadway. Thus, the requirement to signal emphasizes the importance of clear communication during directional changes in more dynamic driving scenarios.