Ampelphasen

Ampelphasen, also known as traffic light phases, are the sequential signals used at intersections to regulate vehicle and pedestrian movement. A typical cycle consists of a red phase, a yellow (amber) phase, and a green phase, each representing specific movement permissions and restrictions. The red phase, often accompanied by an accompanying signal face, obliges vehicles and pedestrians to stop and wait. The yellow phase functions as a warning that the light will soon change to red; drivers are expected to prepare to stop. The green phase permits movement in the designated direction, provided that the signal is not red and no opposing traffic from the same direction is also green.

The timing of each phase is determined by a combination of fixed base times, sensor inputs, and traffic monitoring systems. Fixed-cycle intersections rely on predetermined intervals, whereas adaptive or "smart" systems can modify phase lengths in real time to accommodate fluctuating traffic volumes. Pedestrian phases typically involve a separate walk/don’t walk signal, often synchronized with vehicle phases to prevent conflicting movements.

Intersection design considerations include the length of each phase relative to turning movements, safe stopping distances, and the coordination of multiple intersections along a corridor. In some countries, nighttime or low-visibility conditions trigger extended red or additional cautionary signals. Regulations governing ampelfasens are codified in national and local traffic laws, and motorists are expected to adhere to them to maintain safety and traffic flow.