Research on Travel Time Reliability of Highway Based on Generalized Extremum Distribution

Abstract

Setting up a reasonable reliability evaluation model of highway travel time is of great significance to accurately evaluate the operation state and traffic efficiency. Based on the data collected from the weight in motion system, this paper proposed a method for calculating the travel time of the highway. The probability density histogram of highway travel time is fitted by several distributions such as Log-normal, Weibull, Log-Logistic, Gamma, Generalized Extreme Value (GEV) distribution, and the GEV Distribution with the best fitting degree is selected by using the sum of squared errors, determination coefficient and root mean square error of the fitting curve. The reliability evaluation system is built from four properties which are certainty, volatility, retardance, and failure. On this basis, the reliability of the 24-hour travel time data of a highway section with a length of 21.06km is evaluated to verify the accuracy of this model. The result shows that the GEVD is the best fitting method for highway travel time distribution, and the reliability of passenger car travel time is generally higher than that of the truck. The reliability of bus travel time is the best of sample data, and the reliability of large truck travel time is the worst.