U.S. Consumer Crash Test Results And Injury Risk In Police-Reported Crashes

Monash University Accident Research Centre - Report #191 - 2002

Full report in .pdf format [190KB]

Authors: Stuart V. Newstead, Charles M. Farmer*, Sanjeev Narayan and Maxwell H. Cameron
* Insurance Institute for Highway Safety, Arlington, Virginia U.S.A.

Abstract:

This paper considers relationships between recent U.S. frontal crash test results from the Insurance Institute for Highway Safety (IIHS) and USNCAP, and real-world crash injury risk estimates computed from police-reported crash data from three U.S. states. The frontal crash test results include dummy injury measures by body region from both IIHS offset tests and USNCAP full-width barrier tests plus measures of structural performance from the IIHS offset tests. Individually, results from the full-width and offset tests were not significantly correlated with the real-world injury risk estimates. Stronger relationships were found when a combination of overall ratings from the full frontal and offset tests was used. The current results find only weak correlations between both full-front and offset frontal crash test performance and the real-world injury risk estimates. These weak relationships likely reflect the lack of detail and fundamental difference in injury information in police crash reports compared to that used in deriving crashworthiness ratings from the crash tests.

Executive Summary

Consumer crash test programs provide comparative information on the crashworthiness of new vehicles, which, in turn should predict the performance of the same vehicles in real-world crashes. However, the detail and quality of available information from tests and real-world crashes differ widely, so identifying meaningful relationships between crash test results and real-world crashworthiness can be difficult. Despite these data limitations, studies in the late 1980s and mid-1990s reported positive correlations between dummy injury measures from the U.S. New Car Assessment Program (USNCAP) and real-world fatality rates. More recent analyses of results from Australian crash tests and real-world crashes also have found positive correlations.

The current paper considers relationships between recent U.S. frontal crash test results from the Insurance Institute for Highway Safety (IIHS) and USNCAP, and real-world crash injury risk estimates computed from police-reported crash data from three U.S. states. The frontal crash test results include dummy injury measures by body region from both IIHS offset tests and USNCAP full-width barrier tests plus measures of structural performance from the IIHS offset tests. Individually, results from the full-width and offset tests were not significantly correlated with the real-world injury risk estimates. Stronger relationships were found when a combination of overall ratings from the full frontal and offset tests was used. The current results find only weak correlations between both full-front and offset frontal crash test performance and the real-world injury risk estimates.

These weak relationships likely reflect the lack of detail and fundamental difference in injury information in police crash reports compared to that used in deriving crashworthiness ratings from the crash tests. Police-reported crash data have limited detail on injuries. For example, injuries coded as "serious" by police include significant numbers of injuries that would be classified as minor using the widely accepted Abbreviated Injury Scale (AIS). Also, injury severity is not coded by body region in police data. On the other hand, crash test ratings are based both on dummy measures, which indicate the likelihood of serious and life-threatening injuries to key specific body regions, and on vehicle deformation measures, which also are likely to be related to more serious injuries. Thus it is not necessarily surprising that these various crash test measures are only weakly correlated with real-world injury risk estimates, which are dominated by less serious injuries and cover all body regions. These findings highlight a need for better quality injury information in large-scale real-world crash databases.

Sponsoring Organisations: This project was funded through research contracts with: NRMA Ltd, VicRoads, Royal Automobile Club of Victoria Ltd., Roads and Traffic Authority NSW, Royal Automobile Club of Western Australia Ltd; through a grant from Australian Transport Safety Bureau; and through in kind support from Insurance Institute for Highway Safety