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Safety evaluation for expressways: a comparative study for macroscopic and microscopic indicators
Xiaobo Qu1, Yan Kuang, Erwin Oh
1a Griffith School of Engineering , Griffith University , Gold Coast , Queensland , Australia.
Objective:
This article is to assess the performance of 3 macroscopic safety indicators (speed, speed dispersion, and volume) and two microscopic potential crash risks (time to collision and deceleration rate to avoid crash) on safety evaluation for expressways.
Methods:
Field data were collected at 3 locations for 4 different time periods on an expressway in Beijing, China. The speed of each vehicle, headway time, and vehicle length were recorded by a traffic management system. The 5 safety indicators were thus calibrated on the basis of the collected data. Further, consistency and comparative analyses were applied to assess the performance of indicators.
Results:
According to the analyses, speed dispersion was a better predictor of the two microscopic potential risks compared to the two macroscopic indicators.
Conclusions:
Speed dispersion is recommended to proactively assess road safety because (1) it provides consistent risk evaluation with microscopic potential risks and (2) it makes data collection easier.
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