What does the term 'lost time' refer to in traffic signal management?

• A. Time spent in traffic congestion
• B. Time lost due to signal cycle failures
• C. Time before vehicles can start moving after a signal turns green
• D. Time spent during unusual traffic events

Answer: (C)

The term 'lost time' in the context of traffic signal management specifically refers to the interval where vehicles are unable to move after a traffic signal turns green. This period can occur due to several factors, such as delays in drivers' reactions to the signal change or the need for vehicles to clear the intersection before those waiting can begin to move. This time is crucial for analyzing signal efficiency, as it contributes to the overall cycle length and influences the effective green time available for vehicles to pass through the intersection, ultimately impacting traffic flow and congestion levels. Understanding lost time helps traffic engineers optimize signal timings to enhance the movement of traffic and reduce delays.

In contrast, the other options refer to different aspects of traffic management. Time spent in traffic congestion encompasses much broader delays caused by various factors, including volume overloads and roadway obstructions. Time lost due to signal cycle failures addresses disruptions in signal operations themselves rather than the inherent delays in vehicle movement after a signal change. Lastly, time spent during unusual traffic events refers to irregularities like accidents or construction that can impact traffic flow but do not specifically pertain to the initial delays experienced as signals change to green.