Which of the following is an indication of timing issues during signal changes?

The indication of timing issues during signal changes is best represented by incorrect flash rates. Flash rates are crucial in the operation of traffic signals, especially during transitional periods like changes from green to yellow or red. If there are inconsistencies in the flash rates, it signifies that the timing mechanisms within the signal controller might not be functioning correctly. This could lead to unsafe conditions by not providing adequate time for drivers and pedestrians to react appropriately to changing signals, which can contribute to traffic confusion and accidents.

Other choices like flickering lights, controller alerts, and signal synchronization may relate to the overall functionality of the traffic signal system but do not specifically indicate timing issues during signal changes. Flickering lights might suggest electrical problems, controller alerts may indicate a range of issues not solely related to timing, and synchronization pertains to coordination between multiple signals rather than the timing of a single signal's change. Understanding these subtleties allows traffic signal technicians to diagnose and address timing-related issues effectively.