Trafikhastighet

Trafikhastighet is a term used to describe the speed at which vehicles travel on roads, and it can refer to both the observed speeds of traffic and the speeds allowed by traffic regulations. In planning and research, trafikhastighet is commonly expressed in kilometers per hour (km/h) and is often analyzed using specific measures such as the 85th percentile speed, mean speed, or distribution of speeds. The 85th percentile speed is frequently used as a basis for setting speed limits because it reflects the speed at which most traffic naturally flows under given conditions.

Measuring trafikhastighet involves various data sources and technologies, including road- or pavement-mounted detectors, radar, camera systems, and GPS or probe data from vehicles. These measurements support travel-time estimates, congestion analysis, safety studies, and the evaluation of policy measures. Data on trafikhastighet are also used in dynamic or adaptive speed management systems, which adjust posted limits in response to conditions.

Multiple factors influence trafikhastighet. Road geometry (lanes, curves, gradients), surface conditions, and road maintenance affect driving speeds. Traffic density, incidents, weather, time of day, enforcement, and the mix of vehicle types (cars, trucks, buses) also play substantial roles. Changes in one factor can cause shifts in overall speed and in the variability of speeds across a road segment.

Safety and efficiency trade-offs are central to trafikhastighet. Higher speeds can shorten travel times but increase crash severity and the likelihood of fatal outcomes, while lower speeds often reduce crash risk and improve reliability. Policy tools to manage trafikhastighet include setting speed limits, road design measures, traffic calming, enforcement, and, in some contexts, variable or dynamic speed limits. Understanding trafikhastighet is essential for transport planning, safety analysis, and the design of efficient road networks.