Liiklusvoo

Liiklusvoo (translated as traffic flow) is a concept in transportation engineering that describes how vehicles move along a road or network. It encompasses the rate at which vehicles pass a given point, the average speed of those vehicles, and how densely the road is used. In the literature, three interrelated variables are standard: flow (q), speed (v), and density (k). Flow is typically measured in vehicles per hour, speed in kilometers per hour, and density in vehicles per kilometer. The fundamental relationship is often written as q = v × k, linking how fast traffic travels to how many vehicles occupy a segment of roadway.

The behavior of liiklusvoo is summarized in the fundamental diagram, which shows how flow increases with density up to a peak (capacity) and then decreases as congestion slows traffic. At low density, vehicles travel fast and flow is low; as more vehicles enter the road, speed drops and eventually the road becomes congested, reducing flow. Different traffic conditions, such as free-flow, synchronized flow, and stop-and-go conditions, are reflected in the diagram and in observed patterns of q, v, and k.

Measurement and modeling of liiklusvoo use macroscopic approaches (aggregated quantities like q, v, k) and microscopic approaches (individual vehicle trajectories). Data sources include loop detectors, cameras, GPS and floating-car data, and simulation models range from simple kinematic models to sophisticated, physics-based or agent-based approaches. Applications include road design, capacity analysis, signal timing, and real-time traffic management.