Using State Data to Assess Vehicle Performance Prepared by Rory Austin Office of Vehicle Safety Planning and Analysis National Highway Traffic Safety Administration rory.austin@nhtsa.dot.gov 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

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

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.

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.

“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

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

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

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

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

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

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?

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

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

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

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