Frontal Crash Reconstruction Compared to Event Data Recorders in the Crash Investigation Sampling System Database and the Effect on Injury Risk Models

This study compares statistical models for frontal crash injuries based on delta-v data reported by the vehicle event data recorder (EDR) with injury probability models based on delta-v reconstructed by Crash Investigation Sampling System (CISS) investigators. Injury probabilities and their follow-on use in advanced automatic crash notification (AACN) systems have traditionally been based on delta-v obtained through accident reconstruction of field crashes in the National Automotive Sampling System Crash Data System (NASS-CDS) database. Field delta-v from EDRs in the CISS database is an alternative source of information for crash injury probability modeling. In this study, frontal impact injury risk probabilities computed from EDR and reconstructed delta-v were compared. All data came from the years 2017–2021 of the CISS database, which contains EDR downloads and also reconstructed delta-v using crush measurements and NHTSA’s WinSmash software. On average, CISS reconstructions overestimated delta-v below 16 kph and underestimated delta-v above 16 kph when compared to EDR delta-v. CISS also records detailed injury data using the 2015 Abbreviated Injury Scale (AIS) developed by the Association for the Advancement of Automotive Medicine (AAAM). Statistical analysis was performed using logistic regression to calculate MAIS 1+, MAIS 2+, MAIS 3+, and ISS 16+ injury probabilities. EDR-derived injury probabilities showed a lower risk for serious injury at delta-v above 48 kph when compared to probabilities based on CISS reconstructed delta-v. AACN algorithms are currently based on reconstructed delta-v but are triggered by EDR delta-v in the field. An analysis performed to determine the effect of the difference between the source of delta-v on the AACN notification threshold showed differences for AACN algorithms trained on EDR delta-v compared to reconstructed delta-v. The results of this study showed that the trigger threshold for AACN notification will differ by delta-v source, and this difference leads to variation in injury prediction.