The correlation and Hausdroff dimensions of traffic flow and speed series are analyzed based on the Fractal theory. Using the traffic flow data of four typical expressways in China as input sample, the data statistical results indicates that both synchronized and free flow state are fractal and chaotic. In addition, traffic flow rate and speed time series are determined by different intervals and then G-P arithmetic is applied to estimate their correlation dimensions and the Hausdroff dimension. The results also illustrates that Fractal dimension could by clearly identified, which provides a useful tool for expressway operation management and facilities provision.
Mountainous freeway goes through complex geographic and geological regions and causes safety problem. Making clear of the inner relationship of the crash occurrence and the geometric factors is the most fundamental prerequisite to solve the problem. This paper reveals the contributing geometric factors through analyzing the crash data from Changjin Freeway, a typical mountainous freeway located in Jiangxi Province, China. Based on crash records and designed alignment data, contributing geometric factors are generally classified into three categories: vertical alignment, horizontal alignment, and cross section. And then detailed effects of geometric variables are separately discussed and quantified through the relation with crash rate (CR).
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