Which type of signal operation involves a fixed cycle regardless of traffic?

• A. Pretimed operation
• B. Semi-actuated operation
• C. Full actuated operation
• D. Dynamic operation

Answer: (A)

The concept of pretimed signal operation is centered around the use of a fixed cycle length for traffic signals, which does not adapt to real-time traffic conditions. This means the signal phases are predetermined and remain constant, regardless of the volume of vehicles or pedestrians waiting at the intersection. Such a system is beneficial in areas with relatively steady traffic patterns, where the predictability of signal changes can help improve overall traffic flow without the need for constant adjustments.

In contrast, semi-actuated and full actuated operations rely on real-time traffic conditions. Semi-actuated systems adjust the signal based on input from detectors on one or two approaches, while full actuated systems continuously monitor and manage signal timing based on traffic demand on all approaches. Dynamic operation also involves adapting signal timing based on variable traffic flows, often using advanced technologies for optimization.

Therefore, pretimed operation is distinct in its fixed nature, ensuring that signals turn according to a set schedule rather than adapting to current traffic conditions.