Abstract
Traffic safety is of great significance, especially in urban expressway where traffic volume is large and traffic conflicts are highlighted. It is thus important to develop a methodology that is able to assess traffic safety. In this paper, we first analyze the time to collision (TTC) samples from traffic videos collected from Beijing expressway with different locations, lanes, and traffic conditions. Accordingly, some basic descriptive statistics of 5 locations' TTC samples are shown, and it is concluded that Gaussian mixture model (GMM) distribution is the best-fitted distribution to TTC samples based on K-S goodness of fit tests. Using GMM distribution, TTC samples can be divided into three categories: dangerous situations, relative safe situations, and absolute safe situations, respectively. We then proceeds to introduce a novel concept of the percentage of serious traffic conflicts as the percentage of TTC samples below a predetermined threshold value in dangerous situation. After that, assessment re...
Highlights
Urban expressway is the highest urban road level in Chinese city and is a very important vehicular passageways for motorists and commuters
We conclude that Gaussian mixture model distribution is the best-fitted distribution to time to collision (TTC) samples based on best-fit analysis and the K-S goodness of fit tests suggest the GMM performs very well
GMM is applied to establish the distribution of TTC samples under different traffic conditions
Summary
Urban expressway is the highest urban road level in Chinese city and is a very important vehicular passageways for motorists and commuters. It is necessary to use proximal indirect indicators of safety These “safety indicators” are usually defined as traffic measures that are statistically correlated with the numbers of road traffic accidents at a particular location. Drivers are assumed to be motivated for a safety-related reason to exhibit an accelerating or decelerating response to TTC, and TTC was applied for modeling driving behavior by Van Winsum[22], Jin et al.[23, 24], and Bubb[25] Another important research of TTC is to measure TTC threshold value for distinguish dangerous situation and safe situation. TTC threshold value is related to TTC distributions, and it is difficult for researcher to measure in different traffic conditions For this reason, there is a need to further the concept of traffic safety indicator and assessment method that can indirectly be used to measure expressway traffic safety. The last section concludes with a summary of the findings of this study
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