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Safety Impact Methodology

Safety Impact Methodology. Mikio Yanagisawa RITA / Volpe ITS Connected Vehicle Public Meeting Arlington, VA September 24-26, 2013. Safety Benefits – Basic Equations. Data Sources # Target Crashes : Crash databases (GES, FARS,…)

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Safety Impact Methodology

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  1. Safety Impact Methodology Mikio Yanagisawa RITA / Volpe ITS Connected Vehicle Public Meeting Arlington, VA September 24-26, 2013

  2. Safety Benefits – Basic Equations • Data Sources • # Target Crashes: Crash databases (GES, FARS,…) • Exposure Ratio: Field operational tests and controlled experiments • Crash Prevention Ratio:Field tests, objective tests, controlled experiments, and computer simulation Safety Impact Methodology (SIM) tool

  3. SIM Tool Overview Safety Impact Methodology (SIM) Crashes without V2V Probability of crash V distributions Harm from crashes without V2V SIM Tool Crashes prevented Conflict exposure with/ withoutV2V Harm reduced • SIM estimates effectiveness of individual scenarios • SIM estimates are based on 100% system deployment • SIM tool is developed for evaluation, not design

  4. Rear-End Pre-Crash Simulation VEHICLE Host Vehicle State Remote Vehicle State • Number of Crashes • Number of Non-Crashes • Impact Speed Distribution • ΔV Distribution • Host and Remote Effectiveness Rear-End SIM Simulation DRIVER Reaction Time Braking Level Control vs. Treatment SYSTEM Time-to-Collision of Warning Automatic System Activation

  5. Rear-End Pre-Crash Walkthrough (LVS) Control Treatment

  6. Probability of Crash Estimation Example: Lead Vehicle Stopped – Brake Response Initial Conditions vH = Host velocity TTCwarn= Time-to-collision of warning Driver Response tR = Reaction time from warning aH = Host average deceleration • {IFdstop ≤ dinitialTHEN crash is prevented, ELSE crash occurs} • Run Monte Carlo simulations by drawing random numbers from tR & aH distributions and account for crashes occurred and prevented: • tR & aH from drivers without system assistance • tR & aH from drivers withsystem assistance

  7. Lane Change Pre-Crash Simulation VEHICLE Host Vehicle State Remote Vehicle State • Number of Crashes • Number of Non-Crashes • Impact Speed Distribution • ΔV Distribution • Host and Remote Effectiveness Lane Change SIM Simulation DRIVER Driver Reaction Time Driver Counter Steer Control vs. Treatment SYSTEM Initial Lateral Distance

  8. Lane Change Pre-Crash Walkthrough Control Treatment

  9. Intersection Pre-Crash Simulation VEHICLE Host Vehicle State • Remote Vehicle State • Host Distance and Acceleration (Encroaching) • Number of Crashes • Number of Non-Crashes • Impact Speed Distribution • ΔV Distribution • Host and Remote Effectiveness Intersection SIM Simulation DRIVER Driver Reaction Time Driver Braking Level Control vs. Treatment SYSTEM Time-to-Intersection

  10. Straight Crossing Paths – Both Vehicles Moving Control Treatment

  11. Straight Crossing Paths – Stopped and Starting Control Treatment

  12. Input Parameters *Example Mock Data Driver Reaction (Treatment) • Data • Field • Track • Experiment • Literature • Relationships • Dependencies • Flexible • Variable inputs Link? Link? Link? Brake Force (Treatment) Brake Force (Control) Link? Driver Reaction (Control)

  13. SIM Results and Analysis SIM pCrash Crash Ratio Crash Severity Speed Reduction Analysis Pre-crash mode Crash Count Impact Mode Treatment Type Crash Severity • Results from SIM analyzed for effectiveness • Applied to appropriate target population • Pre-crash scenarios combined • Effectiveness estimates lead to overall benefits

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