# Presentation: 144696

## Evaluation of General Motors Rear-End Collision Warning System

***Wassim George Najm***
- Najm@volpe.dot.gov
- Volpe National Transportation Systems Center
- Research and Special Programs Administration
- U.S. Department of Transportation

- National Intelligent Vehicle Initiative Meeting
- Washington, D.C.
- June 25-26, 2003

**Notes:**
Work was done as part of the Volpe Center’s effort in supporting the Light Vehicle IVI platform
The research presented is the result of discussion and advice from Dr. David Smith, Director of the LV platform from NHTSA

## Presentation Outline

- Background
- Independent Evaluation
- Safety Benefits Estimation
- Concluding Remarks

**Notes:**
In order to better determine the performance specifications and the anticipated benefits for collision avoidance systems, a thorough analysis of the critical event dynamics and the crash contributing factors is needed.  This research focuses on three crash types and provides an analysis of crash contributing factors, a cross-correlation of CFs, and primary contributing factors for each crash type.  

Crash data for this analysis was obtained from the National Automotive Sampling System (NASS) 1997-2000 Crashworthiness Data System (CDS ) and 2000 General Estimates System (GES).

To begin this afternoon’s presentation I will first state the objective of the light vehicle research and then move into a detailed description of the target crash types and subtype definitions used.  Next I will provide an overview of the analysis preformed and then finish with some concluding remarks.

## Project Background

- U.S. DOT Sponsor:** NHTSA**
- Private Consortium:
- System Development and Build: **GM/Delphi**
- Conduct of Field Operational Test:** UMTRI**
- Independent Evaluator: **Volpe Center**

## System Overview

- Integrates Rear-End Crash Warning (RECW) with Adaptive Cruise Control (ACC)
- RECW always functional above 25 mph
- Driver use of ACC is optional
- ACC uses throttle & brake control
- Warnings are visual and audible
- Visual display – Head Up Display** **

## Driving Modes in Field Operational Test

- Baseline (*Without* RECWS) – 1st Week
- Manual
- Conventional Cruise Control
*With* RECAS – 2nd, 3rd, & 4th Weeks
- Manual
- RECW: Six Sensitivity Settings
- RECW+ACC: Six Gap Settings (1 – 2 seconds)

## Independent Evaluation Goals

- Estimate Safety Benefits
- Determine Driver Acceptance
- Characterize System Capability
- Assess Deployment Potential

## Safety Benefits

**Objectives:**
- Driver Performance in Low Risk Driving
- Driver Performance in Driving Conflicts
- Near Crash Experience
- Crash Estimation

## Driver Acceptance

**Objectives:**
- Ease of Use
- Perceived Value
- Ease of Learning
- Advocacy
- Performance

## System Capability

**Objectives:**
- Sensor Suite
- Alert Logic
- Automatic Controls
- Driver-Vehicle Interface

## System Deployment

**Objectives:**
- Market Penetration Forecast
- Additional Activities

## Safety Benefit Measures

- Number of prevented rear-end crashes
- Reduction in *Total Harm* caused by rear-end crash related injuries

## Safety Benefit Estimation Using Driving Conflicts

**Crash**

**Near Crash**

**Driving Conflict**

**Low Risk**

- No. of Prevented Rear-End Crashes=
- System Effectiveness x No. of *Relevant* Crashes
- System Effectiveness ~
- No. of Encounters with Specific Driving Conflict
**Probability of Crash Given Specific Driving Conflict**
- 	(*With* and *Without* RECWS Assistance)

## Probability of Crash Given Driving Conflict

- Estimate Using:
- Kinematic-Based Models:
- Crash Prevention Boundary
- Monte Carlo Simulation
- Distribution of Relevant Performance Parameters:
- Application of Extreme Value Theory

**Crash**

**Near Crash**

**Driving Conflict**

**Low Risk**

## Crash Prevention Boundary

- Conflict: Lead Vehicle Stopped
- Host Vehicle Speed= 30 mph

## Monte Carlo Simulation

- LVS: Lead Vehicle Stopped

## Extreme Value Theory

- Minimum Value Distributions of Relevant Parameters:
- Range
- Available Reaction Time
- Time-to-Collision

## Probability of Crash Estimate Calibration 

## Concluding Remarks

- Estimate safety benefits from driving conflict and near crash performance data.
- Focus on performance in major rear-end pre-crash scenarios.
- Analyze sensitivity of system effectiveness estimates to different conflict and near crash boundaries.
- Assess the accuracy of system effectiveness estimates.
- Account for various factors based on available data.