Novel Crash Surrogate Measure for Freeways

Abstract

In this paper, a disturbance-based methodology was proposed to represent the safety level of a car-following scenario. According to the probabilistic causal model, the following vehicles always take evasive actions to avoid a collision in the crash mechanism. In this study, the probabilistic model is modified to evaluate the maximum disturbance a car-following scenario can accommodate corresponding to the maximum evasive action taken by the following vehicle. This paper aims to investigate the safety level of a car-following scenario by estimating its capability index on accommodating disturbance. The surrogate measure, Disturbance Accommodate Index (DAI), is thus proposed to represent the stability of a car-following scenario by measuring its maximum capability on accommodating disturbance. Further, a case study is conducted to evaluate the performance of DAI by using the traffic and crash data provided by the Department of Transport and Main Roads in Queensland. The results show that the DAI outperforms the other crash surrogate measures (e.g., Aggregated Crash Index, Time to Collision, and Proportion of Stopping Distance) in representing rear-end crash risk, followed by the discussion.