Queue length

Definition

Queue length is the length of the vehicle queue on an approach lane for a specific turning movement at an intersection. It is measured as the distance from the last vehicle in the queue to the stop line when the traffic signal for that movement turns green.

Unit: meters

Calculation logic

The calculation method depends on the available data source, such as data from checkpoint cameras, Amap, or loop detectors.

• Calculation based on checkpoint camera data

  If vehicle data from checkpoint cameras is available for both the upstream and downstream ends of a road segment on an approach lane, this data is used for the calculation. The following diagram shows the calculation logic:

  

• Calculation based on loop detector traffic data

  If checkpoint camera data is unavailable for an intersection, the calculation uses available loop detector traffic data instead. The following diagram shows the calculation logic:

  

  Note: If loop detector traffic data is unavailable, the traffic volume for the cycle is estimated based on the duration of the green phase.