Study on Discrete Characteristics of Urban Expressway Speed and Its Influencing Factors

Abstract

Discrete speed is an important characteristic index that affects the efficiency and safety of urban expressway. In this paper, the individual vehicle speed data collected by Shanghai license plate recognition system is used, and the vehicle speed variance is used as the characteristic index. The discrete characteristics of vehicle speed and its influencing factors are analyzed under the framework of random basic graph. Through analysis, it is found that the individual vehicle speed variance is larger than the aggregate speed variance, and the overall stability is 5~15km/h. As the density increases, it decreases slightly, and can be divided into stable, decreasing, parabolic, and clustered. The main influencing factors of vehicle speed dispersion are identified by establishing multiple linear regression models, including the number of lanes and the type of ramp. This paper expands the basic graph theory of traffic flow and has reference significance for improving the safety and efficiency of urban expressway.