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Freeway safety estimation using extreme value theory approaches: a comparative study.

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  • 1School of Transportation Science and Engineering, Harbin Institute of Technology, China; Department of Civil and Environmental Engineering, Carleton University, Canada.

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Summary
This summary is machine-generated.

This study compares two extreme value theory (EVT) methods, block maxima (BM) and peak over threshold (POT), for predicting freeway crashes using surrogate safety measures. The peak over threshold (POT) approach demonstrated superior performance in data utilization, accuracy, and reliability for safety analysis.

Keywords:
Block maximaExtreme value theoryFreeway safetyPeak over threshold

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Area of Science:

  • Traffic safety engineering
  • Statistical modeling
  • Extreme value theory

Background:

  • The validity of surrogate safety measures is crucial for traffic safety analysis.
  • Extreme value theory (EVT) provides a robust framework for linking surrogate safety measures to crash frequency.

Purpose of the Study:

  • To develop, validate, and compare two EVT modeling approaches: block maxima (BM) and peak over threshold (POT).
  • To apply these models to characterize extreme events and relate surrogate measures to lane change maneuver-related crashes on freeways.

Main Methods:

  • Utilized post encroachment times from 4189 lane change maneuvers on 29 freeway segments.
  • Applied and examined block maxima (BM) and peak over threshold (POT) methods within EVT.
  • Assessed issues of sample size, serial dependency, and non-stationarity for both approaches.

Main Results:

  • The peak over threshold (POT) approach outperformed the block maxima (BM) approach in data utilization, estimate accuracy, and reliability.
  • This finding is particularly relevant under conditions of relatively short observation times.
  • Comparison of estimated crashes and return levels indicated significant variances in crash estimations.

Conclusions:

  • The peak over threshold (POT) method is recommended over the block maxima (BM) method for analyzing freeway safety using surrogate measures.
  • Robust estimated return levels are advised for freeway safety evaluation due to variances in crash estimations.