SLIDE 1:
Overview and Evaluation of the Automotive Collision Avoidance System Field Operational Test (ACAS FOT) 


Jack Ference, NHTSA
Wassim Najm, RITA/Volpe Center


SAE International
2005 Government/Industry Meeting

Washington, D.C.
May 9-11, 2005




SLIDE 2:
Outline

Program Overview:
- Program Phases
- System Description
- FOT Description

Evaluation Overview:
- Analysis Framework
- Safety Benefits Estimation
- Rare Events
- Unintended Consequences


SLIDE 3:
Rear-End Crash Problem
[pie chart

Rear end crash 28% [1,715.000]
other crashes 72% 

* 2003 general estimates system data
* light vehicle crash statistics
* total 6,071,000 police-reported crashes


SLIDE 4:
Automotive Collision Avoidance System Field Operational Test (ACAS FOT) Program

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



SLIDE 5:


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SLIDE 10:

FOT Exposure
[pie charts]

ACAS Disabled
Total Distance Traveled 36,000 Km
	CCC: 21%
	Manual: 79%



ACAS Enabled
Total Distance Traveled 122,000 Km
	ACC: 36%
	Manual: 11%
	FCW: 53%


SLIDE 11:
Independent Evaluation

Goals:
 Estimate Safety Benefits
 Determine Driver Acceptance
 Characterize System Capability



SLIDE 12
Safety Impact
1. Driving Conflict Analysis – Global level examination of all FOT driving conflicts to develop quantitative estimates of overall safety benefits of ACAS.

2. Near Crash Analysis – Detailed Examination of the most severe near crashes to assess the usefulness of ACAS in preventing crashes.

3. Driver Impact Analysis – Examination of driver performance data to identify positive or unintended negative effects of ACAS on driving performance and behavior.




SLIDE 13:
Driving Conflict Analysis
[flow chart]


SLIDE 14:
Driving Conflict Type and Intensity

Driving Conflict Type

- Conflicts: CAMP data from last-second response studies at comfortable braking or steering level.

- Near crashes: CAMP data from last-second response studies at hard braking or steering level.


Driving Conflict Intensity

- Low-intensity: Quantified by TTC versus Range rate diagrams derived from CAMP’s 50%-ile data.

- High-intensity: Quantified by TTC versus Range rate diagrams derived from CAMP’s 95%-ile data. 


SLIDE 15:
Driving Conflict Identification




SLIDE 16:
CONFLICT TYPE AND INTENSITY CLASSIFICATION


SLIDE 17:
Safety Benefits Estimation



SLIDE 18:
EXPOSURE RATIO ANALYSIS

Analysis:
 Comparison between ACAS disabled (1st week) and 2nd half distance traveled with ACAS enabled.

Dynamic Scenarios:
 Lead vehicle stopped
 Lead vehicle moving at slower constant speed
 Lead vehicle decelerating

Measures of Performance:
 MOP1= No. of conflicts per 100 Km traveled
 MOP2= No. of near crashes per 100 Km traveled


SLIDE 19:
PREVENTION RATIO ANALYSIS
Driver Response Analysis:
 Initiation Measures:
 Time-to-collision
 Time headway
 Intensity Measures:
 Minimum time-to-collision
  Peak acceleration
  Average acceleration

Prevention Ratio Estimation:
Monte Carlo simulations based on data from bins with statistically significant difference in response initiation


SLIDE 20:
Rare Events

Analysis of severe near crashes based on response intensity using aggregate numerical data:
 - TTCmin </= 3 seconds and
 - Peak acceleration > 0.3g

Analysis of video episodes triggered by crash imminent alerts that might have prevented a rear-end crash:
 - Driver distraction
 - High peak deceleration






SLIDE 21:
Unintended Consequences

Analysis of low risk (host vehicle @ constant speed) driving performance using numerical data:
- Time headway
- Position within travel lane
- Speed ratio (vehicle speed/speed limit)

Analysis of inattention (distraction or eyes-off-the-road) using alert-triggered video episodes.

Anecdotal remarks based on few observations.


SLIDE 22:
OBSERVATIONS





SLIDE 23:
Questions?
For further information on ACAS FOT program:

Contact Jack Ference:
Tel. (202) 366-0168
E-mail: Jack.Ference@nhtsa.dot.gov

Visit web site:
http://www-nrd.nhtsa.dot.gov/departments/nrd-12/pubs_rev.html