What is the typical duration for a left-turn phase at traffic signals?

Answer: B — 3 to 7 seconds

The typical duration for a left-turn phase at traffic signals generally falls within the range of 3 to 7 seconds. This timing is crucial for managing the flow of traffic, as it allows vehicles making left turns to safely navigate through intersections while minimizing delays for the following traffic. This duration is designed to provide enough time for a left-turning vehicle to clear the intersection without interfering significantly with the movement of opposing traffic. It takes into consideration the reaction time of drivers to start turning once the signal indicates a left turn, as well as the time needed to complete the turn safely. The shorter duration options, such as 1 to 3 seconds, do not provide adequate time for vehicles to perform the maneuver safely, especially in busier intersections. Longer durations, such as 10 to 15 seconds, could disrupt the overall traffic flow and may not be necessary in many situations, leading to increased congestion. Therefore, the 3 to 7 seconds duration strikes a balance between safety and efficiency in traffic signal operations.