The association between data collected in IIHS side crash tests and real-world driver death risk, and opportunities to improve the current test

Teoh, Eric R. / Arbelaez, Raul A.
Insurance Institute for Highway Safety
August 2019

Objective: The Insurance Institute for Highway Safety (IIHS) side crash test has led to crashworthiness improvements, and both overall and component ratings have been shown to be associated with real-world death risk. The objective of the current study was to investigate how crash test measurements, on which component ratings are based, are associated with real-world death risk.
Methods: Driver deaths and police-reported crash involvements were extracted from national crash databases for left-impact crashes of passenger vehicles with standard-feature, head-protecting side airbags for calendar years 2000–2016. Risk of driver death in left-impact crashes was estimated as the number of driver deaths divided by the number of driver police-reported crash involvements. Logistic regression was used to estimate the association between crash test measurements and death risk, controlling for driver and vehicle information.
Results: All crash test measurements investigated were meaningfully associated with driver death risk. For instance, a 10 cm reduction in B-pillar intrusion, a measure of postcrash occupant survival space, was associated with 25% lower driver death risk. For most measures, at least 75% of study vehicles were within the good rating boundary for that measure, and still these measures were associated with driver death risk. Fewer than half of study vehicles earned a good rating for B-pillar intrusion.
Conclusion: Because performance in measures collected in the IIHS side crash test are strongly associated with real-world driver death risk, one of the ways the crash test program could continue to encourage crashworthiness improvements is by strengthening component ratings criteria.