question.md

Designing a Traffic Signal Control System

Requirements

1. The traffic signal system should control the flow of traffic at an intersection with multiple roads.
2. The system should support different types of signals, such as red, yellow, and green.
3. The duration of each signal should be configurable and adjustable based on traffic conditions.
4. The system should handle the transition between signals smoothly, ensuring safe and efficient traffic flow.
5. The system should be able to detect and handle emergency situations, such as an ambulance or fire truck approaching the intersection.
6. The system should be scalable and extensible to support additional features and functionality.

Implementations

Implementation

Classes, Interfaces and Enumerations

1. The Signal enum represents the different states of a traffic light: red, yellow, and green.
2. The Road class represents a road in the traffic signal system, with properties such as ID, name, and an associated traffic light.
3. The TrafficLight class represents a traffic light, with properties such as ID, current signal, and durations for each signal state. It provides methods to change the signal and notify observers (e.g., roads) about signal changes.
4. The TrafficController class serves as the central controller for the traffic signal system. It follows the Singleton pattern to ensure a single instance of the controller. It manages the roads and their associated traffic lights, starts the traffic control process, and handles emergency situations.
5. The TrafficSignalSystemDemo class is the main entry point of the application. It demonstrates the usage of the traffic signal system by creating roads, traffic lights, assigning traffic lights to roads, and starting the traffic control process.