What are the major components of a traffic signal system?

The correct choice highlights the essential components of a traffic signal system, which are critical for its operation and functionality. Signal heads are the physical lights that indicate to drivers and pedestrians when to stop or go. The controller is the brain of the system, managing the timing and sequencing of the signals based on pre-programmed settings and real-time traffic data. Detectors are used to sense vehicular or pedestrian presence, enabling the system to adjust signal phases based on actual traffic conditions, thereby improving flow and safety. The power supply ensures that all these components operate reliably, providing consistent signal operation.

While the other options include related traffic management features, they do not specifically enumerate the vital components that comprise a functioning traffic signal system. For example, barriers, signage, and safety cones are important for traffic management but are not intrinsic to the traffic signal's operational mechanics. Similarly, road markings and speed bumps play roles in guiding and controlling traffic but do not contribute to the signaling process itself. Lastly, while cameras and emergency signals can enhance a traffic management system's effectiveness, they do not form the fundamental structure of a traditional traffic signal system. Therefore, understanding the primary components—signal heads, controllers, detectors, and power supply—is crucial for recognizing how traffic signals operate and facilitate