Abstract
The purpose of this study is to investigate the impact of the truck proportion on surrogate safety measures to explore the relationship between truck proportion and traffic safety. The relationship between truck proportion and traffic flow parameters was analyzed by correlation and partial correlation analysis, and the value of the 85th percentile speed minus the 15th percentile speed (85%V–15%V) and the speed variation coefficient were selected as surrogate safety measures to explore the impact of truck proportion on traffic status. The k-means algorithm and the support vector machine were employed to evaluate traffic status on a freeway under different truck proportions in different periods. The major results are that the relationship between truck proportion and the value of 85%V–15%V and the speed variation coefficient is consistent in different aggregation periods. With increasing truck proportion, the value of 85%V–15%V, as well as the speed variation coefficient, increases initially and then decreases. In addition, the traffic flow status tends to be dangerous when the truck proportion ranges from 0.4 to 0.6 and when the value of 85%V–15%V and the speed variation coefficient are above 42 km/h and 0.223, respectively. While the truck proportion is from 0.1 to 0.3 and from 0.7 to 0.9, the traffic flow is relatively safe on the condition that the value of 85%V–15%V and the speed variation coefficient were under 42 km/h and 0.223, respectively. Therefore, the relationship between truck proportion and traffic safety could be well revealed by two surrogate safety measures, that is, the value of 85%V–15%V and the speed variation coefficient. In addition, the k-means algorithm and the support vector machine can well reveal the impact of truck proportion on traffic safety in different periods. The findings of this study indicate a need for decreasing the disturbance of mixed traffic and the impact of the truck proportion on traffic safety status.
Highlights
Introduction and BackgroundIn China, a total of 83,300 traffic crashes occurred on freeways, the death toll was 5,500, and the number of injuries was 11,500 in 2016 [1]
Dong et al [4] analyzed the influences of risk factors on the frequency and severity of large truck-involved crashes, and the results showed that the severity and frequency of crashes increase significantly when large trucks are involved
Historical traffic crash data and truck-involved crashes are usually used to evaluate the impact of truck performance or parameters on traffic safety, which delays real-time determination of truck proportion on traffic safety. erefore, the aim of this study is to explore the influence of truck proportion on traffic safety by collecting data from surveillance videos
Summary
In China, a total of 83,300 traffic crashes occurred (approximately 30% involved trucks) on freeways, the death toll was 5,500, and the number of injuries was 11,500 in 2016 [1]. In 2014, a total of approximately 0.2 million traffic crashes occurred in Shanxi Province in China, and more than 50% of the crashes involved trucks [1]. The percentage of large crashes involving trucks is high. Erefore, there is a relatively strong relationship between truck proportion and traffic safety. E volume of heavy trucks is relatively large in Shanxi Province. E attendant problem of traffic crashes involving trucks is increasing. Erefore, how to alleviate and eliminate the excessive influence of trucks and truck proportion on freeway operational safety is an urgent problem Due to the obvious difference between the speed of cars and that of large trucks, the behaviors of lane-changing and Journal of Advanced Transportation overtaking of vehicles are too frequent; traffic conflict will increase greatly, which could increase the probability of traffic accidents. ere is an obvious negative impact on the safe operation of trucks on freeways. erefore, how to alleviate and eliminate the excessive influence of trucks and truck proportion on freeway operational safety is an urgent problem
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