In a four-phase signal system, what is provided for both roads?

In a four-phase signal system, the provision of left turn signals for both roads is a critical element of traffic management. This system is designed to optimize traffic flow while ensuring safety for all types of road users. By having dedicated left turn signals, the system can effectively manage the conflict between opposing traffic flows, reducing the likelihood of accidents that can occur when left-turning vehicles interact with oncoming traffic.

The implementation of left turn signals allows for controlled timing that can facilitate safe turns while other phases accommodate through and pedestrian traffic separately. This system enhances the efficiency of signal operations, as it ensures that vehicles can make left turns without the interference of oncoming cars, thereby addressing one of the most common conflict points at intersections.

In contrast, while pedestrian crossing signs and longer green intervals for major roads contribute to traffic management, they do not specifically address the challenges of coordinating left turns in a multi-phase traffic signal context. Simultaneous green lights for all lanes would typically be unsafe and impractical in a four-phase system, as it could lead to severe conflicts among vehicles, compromising safety. Thus, the inclusion of left turn signals is essential for the functionality and safety of a four-phase signal system.