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Are collision and crossing course surrogate safety indicators transferable? A probability based approach using
Attila Borsos1, Haneen Farah2, Aliaksei Laureshyn3
1University of Győr, Department of Transport Infrastructure and Water Resources Engineering, Egyetem tér 1, Győr 9026, Hungary.
Accident; Analysis and Prevention
|June 2, 2020
Summary
This study compares safety indicators like time-to-collision (TTC) and T2 for analyzing near-miss situations. Results show these indicators are transferable, with stricter thresholds for T2 and Peak over Threshold (POT) yielding better safety analysis results.
Area of Science:
- Traffic Safety Research
- Transportation Engineering
- Risk Analysis
Background:
- Traditional crash data has limitations for safety analysis.
- Surrogate safety measures, such as time-to-collision (TTC), are used to assess road user safety.
- Near-miss situations, even without a direct collision course, are relevant for safety analysis.
Purpose of the Study:
- To compare the performance of collision course indicators (TTC) with crossing course indicators (T2) using Extreme Value Theory (EVT).
- To investigate the transferability and optimal conditions for these surrogate safety indicators.
- To evaluate the effectiveness of Block Maxima (BM) and Peak Over Threshold (POT) approaches within EVT for safety analysis.
Main Methods:
- Utilized surrogate safety indicators: time-to-collision (TTC) and T2.
- Applied Extreme Value Theory (EVT) with Block Maxima (BM) and Peak Over Threshold (POT) methods.
- Analyzed vehicle interaction data at a signalized intersection, focusing on left-turning and straight-moving vehicles.
Main Results:
- Both TTC and T2 indicators were found to be transferable across different scenarios.
- Stricter threshold values were required for the T2 indicator to ensure reliable analysis.
- The Peak Over Threshold (POT) approach within EVT provided more reasonable and robust safety analysis results compared to Block Maxima (BM).
Conclusions:
- Surrogate safety indicators, including those for crossing course interactions, can be effectively applied using EVT.
- The transferability of these indicators is confirmed, but requires careful selection of threshold values, particularly for T2.
- The Peak Over Threshold (POT) method is recommended for safety analysis due to its superior performance in estimating crash probabilities from surrogate measures.
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