page_title: Traffic flow
section_title: Traffic light
hierarchical_section_title: Traffic flow / Cumulative vehicle count curves (N-curves) / Applications / Traffic light
caption_attribution_description: English: Departure Curve for a Signal with a Releasing Capacity
context_page_description: In mathematics and transportation engineering, traffic flow is the study of interactions between travellers and infrastructure, with the aim of understanding and developing an optimal transport network with efficient movement of traffic and minimal traffic congestion problems.
context_section_description: A signalized intersection will have special departure behaviors. With simplified speaking, a constant releasing free-flow capacity, μₛ, exists during the green phases. On the contrary, the releasing capacity during the red phases should be zero. Thus, the departure N-curve regardless of arrival will look like as Figure 17 below: counts increase with the slope of μₛ during green, and remain the same during red..
  Saturated case of a traffic light occurs when the releasing capacity is fully used. This case usually exists when the arriving demand is relatively large. The N-curve representation of the saturated case is shown in the Figure 18.
  Unsaturated case of a traffic light occurs when releasing capacity is not fully used. This case usually exists when the arriving demand is relatively small. The N-curve representation of the unsaturated case is shown in the Figure 19. If there is a bottleneck with a capacity of μb(<μₛ) downstream of the light, the ultimate departure of the light-bottleneck system will be that of the downstream bottleneck.
caption: Figure 17. Departure curve for a signal with a releasing capacity
exif: {}