What two checks does the Central Monitoring Unit (CMU) and Maintenance Monitoring Unit (MMU) perform on the controller?

The correct choice encompasses two critical operational factors that the Central Monitoring Unit (CMU) and Maintenance Monitoring Unit (MMU) assess in traffic signal controllers. Proper power and timing functions are fundamental to ensure that the traffic signals operate reliably and effectively.

By verifying proper power, the CMU and MMU check that the signal controller is receiving the adequate voltage and current necessary for its operation, which is essential to prevent failures that could disrupt traffic management. Timing functions, on the other hand, are evaluated to ensure that the signal changes occur as programmed, allowing for the correct flow of traffic and pedestrian safety. Without proper timing, signals could malfunction, leading to unsafe traffic situations.

Overall, these checks are vital to maintaining the integrity and functionality of traffic control systems. The other options, while relevant to traffic signal operations, do not specifically encompass the checks performed by the CMU and MMU as effectively as the proper power and timing functions do.