Liikennevirran

Liikennevirran is a Finnish term meaning traffic flow or traffic stream. In transportation engineering, it denotes the collective movement of vehicles on a road network and the dynamic interaction between density, speed, and flow.

The core relationship is described by the fundamental diagram: flow equals density times speed. As density increases, average speed decreases; flow rises to a maximum at capacity, then declines if congestion worsens. Common states include free flow, synchronized flow, and traffic jam. Understanding Liikennevirran helps explain how small changes in traffic volume can lead to disproportionate changes in travel times and congestion.

Measurement and modeling of Liikennevirran involve road sensors, cameras, and floating-car data to estimate flow, speed, and density. Models range from macroscopic approaches that describe aggregate variables to microscopic models that simulate individual vehicle interactions, as well as mesoscopic methods that bridge the two scales. These tools support both real-time traffic management and long-term planning.

Applications of Liikennevirran analysis include optimizing signal timing, ramp metering, speed limits, and incident management. In planning, traffic flow considerations inform road design, capacity assessments, and the integration of public transit and land use strategies. The goal is to maintain smooth mobility, minimize delay, and improve safety across the network.

In Finland, Liikennevirran is commonly used in academic and professional texts to refer to traffic flow. It should not be confused with Liikennevirasto, the former state transport agency that was reorganized into Väylävirasto in 2019.