Modeling Freeway Real-Time Operating Safety Evaluation Based on Fault Tolerance

This paper first analyzes the influence of the dynamic changing of weather, road and transportation on freeway operating safety. For the purpose of accidents avoidance, 4 safety grades are defined based on fault tolerance of traffic flow. Fault tolerance represents the risk of rear-end while driving on freeway. Good fault tolerance means even if some accidents happen on one or several vehicles, other vehicles would still stay safe and the entire traffic flow could be ensured to pass safely. Based on the analysis of dynamic data of weather, road and traffic condition collected by freeway monitor system, the dynamic thresholds of speed and density are determined. Finally the real-time safety grade of freeway is obtained by comparing the dynamic thresholds with the real-time speed and density. The simulation results show that the freeway real-time operating safety evaluation model based on fault tolerance proposed in this paper could be used to not only estimate the real-time driving risk of vehicle under different weather, road and traffic condition, but also evaluate the impact of management. The evaluation results match reality pretty well. The model is suitable for the freeway with complete information collection devices and high-level informatization. For the covering abstract see ITRD E138091. This paper is available from


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  • Accession Number: 01109286
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Aug 25 2008 8:02AM