OPERATING SPEED ON URBAN ROAD NETWORK - CASE STUDY IN RIJEKA, CROATIA

Speed is an important factor for road capacity and road safety level. It is the main reason for almost all types of traffic accidents on road network outside but also inside urban areas. Traffic speed is affected by different parameters such as traffic regulation and traffic signs, road geometry and road environment in general. Different researchers show that operational speed, measured on the road network, is different than design speed or posted speed limit. As in urban areas, there are many roads (mainly primary roads) with heterogeneous traffic (pedestrians, personal vehicles, bicycles.) the problem of speed control and prediction becomes even more complex than on roads outside of urban areas. In this paper, an overview of parameters affecting speed on the urban road network is done. Also, preliminary analyses of measurements done on the primary road network in Rijeka city is presented. Speeds were measured on the main primary road network in order to compare it with allowed speeds and other road parameters. The measurements were done on different types of road sections and the correlation between allowed and operational speed was established.