What are the two primary types of transit vehicle preemption systems?

The two primary types of transit vehicle preemption systems are optical and radio systems.

Optical preemption systems use light-based technology, typically involving sensors that detect the presence of a transit vehicle through reflections or direct light signals. These systems can involve light-emitting devices on the transit vehicle that communicate with sensors at the traffic signal. This method provides a reliable means to identify approaching vehicles and prioritize their movement through intersections, thereby enhancing the speed and efficiency of public transportation.

Radio preemption systems operate through wireless communication between transit vehicles and traffic control equipment. They typically utilize radio frequency signals to convey the presence and approach of a transit vehicle to the signal controller. This type of system can cover greater distances and penetrate urban infrastructure more effectively than optical systems, making it suitable for various environments.

Other options, while they might involve technologies related to traffic signals, do not represent the primary types of transit vehicle preemption systems. Thus, understanding the distinct characteristics and operational methods of both optical and radio preemption systems is crucial for efficient traffic management and improving the overall effectiveness of transit operations.