Abstract.Urban streets classification systems are the basis for defining function and, in turn, the design criteria for the world’s streets networks. The traditional classification systems have been based on the mobility and access functions of roads for motor vehicle traffic. Other road users and road uses have been largely ignored in this important step of the road design process. The present paper proposes a novel generalization model for selecting characteristic streets in an urban street network. This model retains the central structure of a street network, it relies on a structural representation of a street network using graph principles where vertices represent named streets and links represent street intersections. Increasing the density in the urban streets causes the increase of the delay time of traveling, so the cities traffic management emphasizes that determining condition of the urban streets construction is a priority. The arrangement condition of the urban streets in the transportation network can affect the reliability and decrease the trip delay time. In this paper reliability is calculated, using probability theory according to the density and the delay caused by arrangement condition of the urban streets in the streets network. This model has been used for arrangement condition of urban intersections and streets and it has been examined.

Keywords: urban streets network, reliability theory, graph modeling, functional classification system (FCS)