Injury Risk Assessments in Real- Life Frontal Collisions
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EVALUATION OF EVENT DATA RECORDERS IN FULL SYSTEMS CRASH TESTS Peter Niehoff Rowan University United States Hampton C. Gabler Virginia Tech United States John Brophy Chip Chidester John Hinch Carl Ragland National Highway Traffic Safety Administration United States Paper No: 05-0271 ABSTRACT Although manufacturers have assigned many different names to these devices, NHTSA refers to The Event Data Recorders (EDRs), now being them generically as Event Data Recorders (EDRs). installed as standard equipment by several Perhaps the single data element most important to automakers, are increasingly being used as an crash investigation is the vehicle’s change in velocity independent measurement of crash severity, which or delta-V, a widely accepted measure of crash avoids many of the difficulties of traditional crash severity. The traditional method of determining reconstruction methods. Little has been published delta-V, based upon correlations with post-crash however about the accuracy of the data recorded by vehicle deformation measurements, has not always the current generation of EDRs in a real world been successful or accurate [Smith and Noga, 1982; collision. Previous studies have been limited to a O’Neill et al, 1996; Stucki and Fessahaie, 1998; single automaker and full frontal barrier impacts at a Lenard et al, 1998]. By directly measuring vehicle single test speed. This paper presents the results of a delta-V, EDRs have the potential to provide an methodical evaluation of the accuracy of new- independent measurement of crash severity, which generation (2000-2004) EDRs from General Motors, avoids many of the difficulties of crash Ford, and Toyota in laboratory crash tests across a reconstruction techniques [Gabler et al, 2004]. wide spectrum of impact conditions. The study evaluates the performance of EDRs by comparison Little has been published however about the accuracy with the laboratory-grade accelerometers mounted of the data recorded by the current generation of onboard test vehicles subjected to crash loading over EDRs in a crash. Previous studies on the accuracy of a wide range of impact speeds, collision partners, and older-generation EDRs exist, but have been crash modes including full frontal barrier, frontal- somewhat limited in the range of conditions used. In offset, side impact, and angled frontal-offset impacts. a study conducted by Transport Canada and General The study concludes that, if the EDR recorded the Motors (GM), Comeau et al (2004) examined the full crash pulse, the EDR average error in frontal accuracy of the delta-V versus time data recorded by crash pulses was just under six percent when GM EDRs in eight separate crash tests involving compared with crash test accelerometers. In many three vehicle models. EDR delta-V was reported to cases, however, current EDRs do not record the be ±10% of the delta-V as measured by the crash test complete crash pulse resulting in a substantial instrumentation. The paper stated that this EDR underestimate of delta-V. accuracy was within the manufacturer’s tolerances on cumulative delta-V. Chidester et al (2001) examined INTRODUCTION the performance of EDRs from model year 1998 GM passenger vehicles. Accuracy was considered to be The Event Data Recorders, now being installed as acceptable, however occasionally the EDRs would standard equipment by several automakers, are report slightly lower velocity changes than crash test designed to record data elements before and during a accelerometers. Lawrence et al (2003) evaluated the collision that may be useful for crash reconstruction. performance of GM EDRs in 260 staged low-speed Niehoff 1 collisions and found that the EDRs underestimated delta-V. It was found that errors of greater than ANALYSIS 100% were experienced during collisions with a delta-V of 4 km/hr. These errors declined to a EDR Data Collection maximum of 25% at 10 km/hr. For all GM vehicles and two of the Ford vehicles, the OBJECTIVE EDR data were retrieved using the Vetronix Crash Data Retrieval System. This device provides The primary objective of this study is to establish the interfacing hardware and software, which permits accuracy of EDR measurements recorded during full data retrieval for certain passenger vehicles. systems crash tests. Currently, the Vetronix system can retrieve data from most General Motors vehicles manufactured since APPROACH model year 1996, some pre-1996 GM models, and a limited number of Ford models. For EDRs not Our approach was to evaluate the performance of readable by the Vetronix system, Ford and Toyota EDRs in laboratory crash tests across a wide Motor Companies downloaded the EDR data for this spectrum of impact conditions. The study is based study using a different technique. upon crash tests conducted by both the National Highway Traffic Safety Administration (NHTSA) Thirty of the thirty-seven vehicles tested employed and the Insurance Institute for Highway Safety GM EDRs. The GM EDRs in these vehicles have a (IIHS). In a crash test, passenger vehicles are maximum recording time of 150ms in most cases, instrumented with high-precision laboratory-grade with a typical recording duration between 100 and accelerometers that can be used as a benchmark 150ms. Change in velocity is recorded at 10ms against which to compare EDR measurements. By intervals. With the exception of the Chevrolet validating the EDRs against crash test Malibu, the GM EDR records only longitudinal delta- instrumentation onboard the subject vehicles, this V. The 2004 Chevrolet Malibu, the most advanced paper will investigate EDR performance across a GM EDR used in this study, records delta-V in both range of impact speeds, collision partners, and crash the longitudinal and lateral directions for up to 300 modes including full frontal barrier, frontal-offset, ms. The remaining vehicles were Fords and side impact, and angled frontal-offset impacts. Toyotas, which utilize a different type of data recorder. The EDRs used in Ford vehicles record As shown in Table 1, data used in this evaluation was acceleration at 1ms intervals. Of the four Ford collected from thirty-seven separate crash tests. EDRs, two are of an older type that record for a These collisions varied in both severity and type. duration of approximately 70ms, and two are a newer Twenty-seven of these crash tests were performed by version that record for approximately 120ms. Toyota the NHTSA. The remaining ten tests were conducted EDRs used in this study record velocity for 150ms in by the IIHS. Most collisions were frontal impacts of 10ms intervals. Both the Ford and Toyota data some sort, with approach velocities ranging from 25 recorders only record velocity along the longitudinal to 40mph. Our data set included one side impact. axis. Twenty-five of the NHTSA tests were full frontal rigid-barrier collisions. Eighteen of these collisions Crash Test Instrumentation Selection were conducted with a vehicle approach speed of 35mph, two at 30mph and five at 25mph. The The EDRs used in our study measured the remaining NHTSA tests include one 25mph 40% acceleration of the occupant compartment during the offset frontal collision, and one vehicle-to-vehicle crash event. Measurements were compared with collision. The vehicle-to-vehicle collision was crash test accelerometers, which were also mounted conducted using a principal direction of force of 345 in the occupant compartment. The accuracy of the degrees and a closing velocity of 68mph. Nine of the crash test accelerometers was evaluated by IIHS tests were frontal offset tests conducted at an comparison with other accelerometers in the approach velocity of 40mph and an overlap of 40% occupant compartment to ensure that they were into a deformable barrier. IIHS conducted the only internally consistent with one another. Crash test side-impact test in our data set. Several other EDRs accelerometers mounted in either the crush zone or to were to be used for the comparisons, but were the non-rigid occupant compartment components, omitted due to malfunction of the EDR. e.g. the instrument panel, were not used in this study. Niehoff 2 Table 1. Data Set Description Closing Impact EDR Model Test Vehicle Description Speed1 Angle Overlap Barrier Number (mph) (deg) 3851 2002 Chevrolet Avalanche 35.1 0 0 Rigid SDMG2001 3952 2002 Buick Rendezvous 35.1 0 0 Rigid SDMDG2002 4198 2002 Saturn Vue 35.0 0 0 Rigid SDMD2002 4238 2002 Cadillac Deville 35.3 0 0 Rigid SDMGF2002 4244 2002 Chevrolet Trailblazer 35.1 0 0 Rigid SDMGT2002 4437 2003 Chevrolet Suburban 24.8 0 40% Rigid SDMGF2002 4445 2003 Chevrolet Cavalier 34.7 0 0 Rigid SDMG2001 4453 2003 Chevrolet Silverado 24.3 0 0 Rigid SDMGF2002 4454 2003 Chevrolet Tahoe 24.3 0 0 Rigid SDMGF2002 4464 2003 Chevrolet Avalanche 35.1 0 0 Rigid SDMGT2002 4472 2003 Chevrolet Silverado 34.7 0 0 Rigid SDMGF2002 4487 2003 Saturn Ion 34.8 0 0 Rigid SDMDW2003 4567 2003 Chevrolet Suburban 35.0 0 0 Rigid SDMGF2002 4702 2002 Saturn Vue 29.7 0 0 Rigid SDMD2002 4714 2002 Saturn Vue 29.7 0 0 Rigid SDMD2002 4775 2004 Pontiac Grand Prix 34.7 0 0 Rigid SDMDW2003 4846 2004 Toyota Sienna 35.1 0 0 Rigid 89170-08060 4855 2004 Toyota Solara 34.7 0 0 Rigid 89170-06240 4890 2004 Ford F-150 35.0 0 0 Rigid ARM481+ 4899 2004 Cadillac SRX 35.1 0 0 Rigid SDMGF2002 4918 2004 GMC Envoy XUV 35.0 0 0 Rigid SDMGT2002 4923 2004 Chevrolet Colorado 35.2 0 0 Rigid SDMGF2002 4955 2000 Cadillac Seville 70.4 330 50% Vehicle SDMG2000 4984 2004 Saturn Ion 24.8 0 0 Rigid SDMDW2003 4985 2005 Chevrolet Equinox 35.0 0 0 Rigid SDMDW2003 4987 2005 Ford Taurus