Rollovers of the future: strong roofs, ESC, and curtain airbags Matthew Brumbelow SAE Government / Industry Meeting 30 January 2013
Occupant fatalities per 1 million registrations Fatality rates in 1-3 year old SUVs and cars 80 1-3 year old SUVs: front 70 1-3 year old SUVs: side 60 1-3 year old cars: front 1-3 year old cars: side 50 40 30 20 10 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Occupant fatalities per 1 million registrations Fatality rates in 1-3 year old SUVs and cars 80 70 60 50 1-3 year old SUVs: front 1-3 year old SUVs: side 1-3 year old SUVs: rollover 1-3 year old cars: front 1-3 year old cars: side 1-3 year old cars: rollover 40 30 20 10 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Occupant fatalities per 1 million registrations Rollover fatality rates in 1-3 year old pass. vehicles 80 70 60 1-3 year old SUVs: rollover 1-3 year old cars: rollover 1-3 year old pickups: rollover 50 40 30 20 10 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Many factors are likely contributing to reduced rollover fatality rate Impact of economic recession Improvements in static stability factor (especially SUVs) Increased belt use rates Increased ESC fitment rates Increased side curtain airbag fitment rates Increased roof strength
Percentage of vehicles with ESC standard Electronic stability control Estimated 73 percent reduction in fatal single-vehicle rollover crash rates due to ESC (Farmer 2010) FMVSS 126 issued in 2007, required complete phase-in for 2012 model year SUV fitment rates were far ahead of FMVSS requirements 100 80 60 SUVs Cars Pickups 40 20 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Model year
Percentage of vehicles with standard head protecting SAB Curtain airbags Side impact protection has driven fitment of airbags Many curtain airbags have not been linked to roll sensors (especially in cars) FMVSS 226 will phase-in over 2014-2017 model years 100 80 60 40 20 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Model year
SWR Roof strength Estimated 23 percent reduction in fatal/incapacitating injury risk for a 1.0 unit SWR increase (Brumbelow and Teoh, 2009) IIHS rating system began in 2009; FMVSS 216 upgrade will phase-in over 2013-2017 model years 7.0 6.0 5.0 IIHS rating test IIHS or NHTSA research test Model year average 7.0 6.0 5.0 4.0 4.0 3.0 3.0 2.0 2.0 1.0 1.0 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 First model year of tested vehicle
How will future rollovers be different? Will ESC presence shift the average crash severity? Unsuccessful ESC interventions could still reduce speed entering roll Rollovers which ESC is unable to prevent may be more severe or otherwise initiated differently Will curtain airbags and stronger roofs produce a shift in the relative prevalence of injury types? Does the amount/type of vehicle deformation change with higher roof strength (as measured in FMVSS 216 configuration)? Questions like these should inform current research efforts
NASS-CDS query Vehicles with Good IIHS roof strength ratings (SWR 4.0) Calendar years 2003-2011 Two or more quarter-turns Total cases 61 With standard ESC 19 With curtain SAB linked to roll sensor (all had ESC) 12 With other inflated curtain SAB 12 Total VMAIS 3 8 In lateral rolls (n=58) 6 In end-over-end rolls (n=3) 2 In vehicles with both curtains deployed (n=18) In vehicles with one curtain deployed (n=5) 1 0 (1 unk due to fire)
Number of quarter-turns Rollovers by quarter-turns and ESC/curtain status Excluding 5 cases with unknown MAIS or countermeasure End-over-end 11 10 ESC standard, no curtain deployment 9 8 7 ESC not standard, curtain deployment ESC standard, curtain deployment 6 5 4 3 2 ESC not standard, no curtain deployment VMAIS 0-2 VMAIS 3+ 1 0 0 5 10 15 20 25 30 Number of cases
2011-12-051 ESC, no curtains No obvious control loss, drove off road, hit ditch and flipped forward onto roof. Unbelted driver had AIS3 spinal cord contusion, lumbar spine burst fracture.
2009-76-073 ESC+curtains Case vehicle struck in left rear by oncoming vehicle, rotated CCW, rolled right 4 quarter-turns. Appears to have landed on back left corner of roof. Belted 69 year-old driver had AIS 1 leg strain, skin injuries. Belted 96 year-old front passenger had AIS 1 facial skin injuries. Both curtains, left torso SAB deployed.
MAIS3+ rate Injury severity compared to SWR<4 vehicles Lateral rollovers with 2-8 quarter turns for all 2007+ MY, excluding SWR>4 cases (N=316) 0.80 0.70 0.60 0.50 Raw Weighted 0.40 0.30 0.20 0.10 0.00 2 3 4 5 6 7 8 9 Number of quarter turns SWR 4 cases Raw Weighted Expected MAIS3+ 17.2 1548 Actual 6 682 Rate Ratio 0.35 0.44
No std ESC Std ESC Roll initiation and duration by ESC presence Raw Weighted Raw Weighted Preceding impact 18 3190 6+ quarter-turns 3 287 Total 19 3337 Total lateral R/O 18 3210 Rate 95% 96% Rate 17% 9% Preceding impact 29 4278 6+ quarter-turns 13 2726 Total 42 6750 Total lateral R/O 40 6678 Rate 69% 63% Rate 33% 41% 100% 80% Standard ESC No standard ESC 60% 40% 20% 0% Raw Weighted Raw Weighted Preceding impact 6 or more quarter turns
Observations Rollover fatalities likely will continue falling as proportion of vehicles in fleet with ESC/curtains/high-SWR increases Still very few relevant NASS-CDS cases No known case of AIS 3 injury in a vehicle with ESC, roll-activated curtains and SWR 4 (n=12) Likely that an increased proportion of future rollovers will be preceded by other impacts based on available data Likely that average roll duration (quarter-turns) will be reduced based on available data
Future work Continued need to better understand effect of current countermeasures Previous analyses of NASS-CDS rollovers (e.g. prevalence of various injury types/mechanisms, occupant positioning for dynamic testing) could be misleading when evaluating current priorities IIHS will continue to monitor NASS-CDS for relevant cases; important that NASS continues to provide source of crashworthiness data after NHTSA s Data Modernization effort IIHS continues monitoring state crash databases for sufficient data Could allow individual injury risk effect estimates for ESC, curtains, and SWR values beyond 4.0
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