Ligduur

Ligduur is a term used in traffic engineering to denote the duration of a signal phase at a traffic light, typically expressed in seconds. The term can refer to any phase in a signal cycle—green, yellow, or red—but is most often discussed in relation to the green phase, sometimes called de groene ligduur. The ligduur for an approach is defined in a signal timing plan and depends on factors such as traffic demand, pedestrian crossing times, and safety margins for clearing vehicles before a phase changes.

Determining ligduur: In fixed-time plans, ligduur is set for each cycle based on estimated traffic volumes to balance throughput and delays. In actuated or adaptive systems, detectors adjust the ligduur in real time within predefined minimum and maximum limits, allowing the timing to respond to actual conditions.

Typical values: Cycle lengths commonly range from about 60 to 120 seconds. Green times per approach vary widely, often from roughly 15 to 60 seconds, depending on the number of lanes, opposing traffic, pedestrian needs, and overall signal coordination with neighboring intersections.

Impact and considerations: Longer greens can increase throughput for the approach but may extend delays for other directions and pedestrians. Shorter greens reduce wait times for some but can lead to more stops and lower capacity. Designers also account for safety margins, yellow and red intervals, and the overall synchronisation of an intersection.

See also: verkeerslicht, signaalplan, groenfase, cyclus.