Occupant Responses in High-Speed Rear Crashes: Analysis of Government-Sponsored Tests

The objective of this study was to analyze available anthropomorphic test device (ATD) responses from FMVSS 301-type rear impact tests. Rear impact test data was obtained from NHTSA and consisted of dummy responses, test observations, photos and videos. The data was organized in four test series: 1) NCAP series of 30 New Car Assessment Program tests carried out at 35 mph with 1979-1980 model year vehicles, 2) Mobility series of 14 FMVSS 301 tests carried out at 30 mph with 1993 model year vehicles, 3) 301 MY 95+ series of 79 FMVSS 301 tests carried out at 30 mph with 1995-2005 model year vehicles and 4) ODB series of 17 Offset Deformable Barrier tests carried out at 50 mph with a 70% overlap using 1996-1999 model year vehicles. The results indicate very good occupant performance in yielding seats in the NCAP, Mobility and 301 MY 95+ test series. When the dummy responses were normalized by injury assessment reference values (IARVs), the largest normalized responses were 39.5% ± 27.2% (average ± standard deviation) for head acceleration and 46.6% ± 27.0% for chest acceleration in the passenger NCAP series. The tests demonstrate occupant retention on the seat with the lap-shoulder belted dummy and low risks of injury to the head, neck and chest. The yielding seats rotate rearward in the high-speed crashes and provide occupant protection. Dummy responses were higher in the more severe ODB series. The average normalized HIC was 98.3% ± 59.4% for the near-side dummy and 105.4% ± 77.5% for the far-side dummy. The largest normalized neck response was the lower-neck extension moment at 117.7% ± 79.6% for the near-side dummy and 96.7% ± 47.5% for the far-side dummy. The dummy responses and kinematics in the 301-type rigid barrier tests are consistent with the very low risk of severe injury (MAIS 4+) in rear-impact field accidents. NASS-CDS data shows a risk of only 0.26% ± 0.13% for MAIS 4+ injury in 20-25 mph rear delta V crashes and 0.19% ± 0.13% in 25-30 mph delta V crashes. The NHTSA crash tests and field accident data show that yielding seats of varying strength provide occupant protection in high-speed rear impacts.