Relationships among flow, speed and density.
Fundamental relation q=k·v (flow = density × speed); Greenshields linear model gives capacity at half jam density. Shockwaves, queuing, level of service, and microscopic car-following models. Capacity of a freeway lane is about 2000 veh/h.
Stop-and-go waves form when density exceeds capacity.
Traffic flow theory explains how flow, speed and density interact, which guides capacity planning and congestion management.
Relationships among flow, speed and density.
Traffic flow theory explains how flow, speed and density interact, which guides capacity planning and congestion management.
A relationship between flow, speed and density, where flow peaks at a critical density and then falls as congestion grows.
Flow above capacity at a bottleneck builds a queue that spreads backwards, and the queue then slows traffic upstream.
Typical applications include estimating the capacity of a motorway lane under peak demand, analysing the effect of a bottleneck on queue length and designing ramp metering to keep flows at a stable level.
Study "Pavement design" first (topic 94 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
Fundamental diagram. Headway and spacing. Bottlenecks.
Stop-and-go waves form when density exceeds capacity.
The next topic is "Intersections and signals", which builds directly on this one.
It is classed as Advanced in Civil & Structural (topic 95 of 112). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Civil & Structural.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.