The concept of a vertical queue is often used in

traffic flow In mathematics and transportation engineering, traffic flow is the study of interactions between travellers (including pedestrians, cyclists, drivers, and their vehicles) and infrastructure (including highways, signage, and traffic control devi ...

studies as a common assumption to simplify analysis problems. Its use enables many calculations to be simplified, allowing researchers to get to the core of their problem, while ignoring the effects of

queue __NOTOC__ Queue () may refer to: * Queue area, or queue, a line or area where people wait for goods or services Arts, entertainment, and media *''ACM Queue'', a computer magazine * The Queue (Sorokin novel), ''The Queue'' (Sorokin novel), a 198 ...

buildup on a roadway. Vertical queues can also be used in

traffic signal Traffic lights, traffic signals, or stoplights – known also as robots in South Africa are signalling devices positioned at road intersections, pedestrian crossings, and other locations in order to control flows of traffic. Traffic light ...

analysis, with vertical queues occurring at the location of the stop bar.

Concept usage

The vertical queue assumption presumes that vehicles on a roadway do not back up over the length of the roadway, which would be considered a horizontal queue, but rather stack up upon one another at the point where congestion begins or at the stop line of a

. The vertical queue is unitless, and is simply representative of the number of vehicles which are delayed at a given point in a system. This is clearly not possible in real life, but the assumption allows vehicles in an

analysis Analysis ( : analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...

to drive at the free flow speed until reaching the point of congestion. A vehicle does not have to travel at less than the free flow speed due to a road being congested because of a horizontal queue. This simplification is widely accepted by traffic flow theorists. Vehicles enter the vertical queue at the top of the stack and depart from the bottom. The first vehicle to arrive at the point of congestion would thus be at the bottom of the vertical queue. Vehicles incur no delay traveling to the point of congestion, and travel to the point at which the vertical queue occurs without hindrance. The vehicles only incur delay while in congestion or at the stop line. The time vehicles spend within the vertical queue is the difference between the undelayed travel time to the point of congestion and the actual travel time. It is equal to the delay incurred before the point of congestion.

References

{{Reflist Road transport