What’s the Purpose of That Little White Device on the Traffic Light Pole?

monitor a specific area of the lane. If your car stops outside that area, the system may not register it as expected.

The sensor may have a limited detection range
Different devices are designed to detect vehicles at different distances and locations.

The system may be using a fixed timing schedule
Not every intersection changes its timing based on vehicle detection. Some signals follow a preset cycle regardless of how many cars are waiting.

A detection device may need maintenance
Like any electronic equipment, traffic sensors can malfunction or become obstructed. A problem may prevent the system from detecting vehicles