1. Using State Data to Assess Vehicle Performance
Prepared by Rory Austin
Office of Vehicle Safety Planning and Analysis
National Highway Traffic Safety Administration
Presented by John Kindelberger National Center for Statistics and Analysis
30th International Traffic Records Forum
Nashville, TN
July 26, 2004
Paper is a Comparison Study
- Oldest Age groups vs. Younger groups
- Examines occupant safety in the context of vehicle type and crash type issues
- Includes travel and crash exposure, fatalities, injuries, and injury severity
Background
- Older population trends
- Past
Exposure
- Measures of exposure
Outcomes
- Crash Involvement
- Occupant Fatalities
- Occupant Injuries
- Severity of Injuries
Discussion
- Conclusion
- NHTSA Action Items

2. Presentation Overview
Why Assess Vehicle Performance?
Example 1: Vehicle Crash Protection for Children
Example 2: Vehicle Braking Performance
Conclusion
Paper is a Comparison Study
- Oldest Age groups vs. Younger groups
- Examines occupant safety in the context of vehicle type and crash type issues
- Includes travel and crash exposure, fatalities, injuries, and injury severity
Background
- Older population trends
- Past
Exposure
- Measures of exposure
Outcomes
- Crash Involvement
- Occupant Fatalities
- Occupant Injuries
- Severity of Injuries
Discussion
- Conclusion
- NHTSA Action Items

3. Why Assess New Vehicle Performance?
Compliance with Federal Regulations
New vehicles must meet Federal Motor Vehicle Safety Standards (FMVSS)
Consumer Information
New vehicles are assigned ratings under NHTSA’s New Car Assessment Program (NCAP)
New vehicle performance narrows the scope.

4. Measuring Vehicle Performance
Compliance and NCAP
Laboratory tests
Described in the Code of Federal Regulations
However… Do Laboratory Results Correlate with “Real-World” Performance?
Want changes to FMVSS to have safety benefit
Want to provide consumers with “good” information
This is really measurement validity.

5. “Real-world” Performance
Frequently determined from crash data
NHTSA’s State Data System (SDS) useful
Large numbers of cases needed for
Particular vehicle make and model
Relatively new vehicles (recent model years)
Vehicle Identification Numbers needed for
Identifying particular vehicle characteristics such as four-wheel drive or anti-lock brake system
Possible discussion of SDS, note not all states provide VINs

6. Example 1: Vehicle Crash Protection for Children
Do some vehicle models provide better occupant protection for properly restrained children than other vehicle models?
Focused on
Frontal crashes (front impact)
Vehicle that did not overturn
15 vehicle models
Model years 2000 through 2003

7. Example 1: Vehicle Crash Protection for Children
Child occupants were
0 to 3 years old
In rear seat
In child restraint
Known injury severity (including no injury)
Older children were not included due to coding issues with booster seats

8. Example 1: Methodology Vehicle Performance for Vehicle Model =
Number of Injured Children in Relevant Crashes
in Vehicle Model /
All Children in Relevant Crashes
in Vehicle Model
Approach requires information on ALL children
Not just injured children
Example of crashworthiness – what happens given a crash occurs

9. Example 1: Data Sets Used
Used Florida and Maryland
Some states could not be used because
No VINs
No information on uninjured occupants
No initial impact point
Not current enough to capture “new” model years

10. Example 2: Braking Performance
Do some vehicles have better braking performance than other vehicles?
Important because better brakes may help avoid a crash
Rear-end crashes
If following (striking) vehicle had stopped sooner, crash might not have occurred

11. Example 2: Braking Performance
But raw counts of rear-end crashes per vehicle model may reflect exposure
More vehicles of a particular model on the road
Vehicle models differ in miles traveled
Vehicle models differ in environment
Region or urban vs. rural
How can we control for exposure?

12. Example 2: Methodology
Exposure to rear-end crashes can be captured by involvement
leading (struck) and following (striking)
Higher volume models and certain travel patterns contribute to higher involvement
Potential measure of braking performance
Vehicles of model striking in rear-end crash / Vehicles of model involved in rear-end crash

13. Example 2: Methodology Braking performance still affected by driver
Can control through use of logistic regression
Predict whether a vehicle in rear-end crash was striking (brake performance) or struck (control)
Explanatory variables include vehicle model, age, gender, and alcohol/drug involvement
Explanation by vehicle model indicates differences in braking performance

14. Example 2: Data Sets Used
Used Florida, Maryland, Missouri, Pennsylvania, and Utah
Needed VINs to identify vehicles with standard Anti-Lock Brakes
Involved 20 vehicles of model years 1998 through 2003

15. Conclusions
Both projects relate to possible consumer information programs under consideration
Final decisions have not been made regarding either project but…
State data is greatly informing our decision-making process AND
Will help all of us improve vehicle safety