Objectives: Earlier research has shown that the rear row is safer for occupants in crashes than the front row, but there is evidence that improvements in front-seat occupant protection in more recent vehicle model years have reduced the safety advantage of the rear seat versus the front seat. The study objective was to identify factors that contribute to serious and fatal injuries in belted rear-seat occupants in frontal crashes in newer model year vehicles.
Methods: A case series review of belted rear-seat occupants who were seriously injured or killed in frontal crashes was conducted. Occupants in frontal crashes were eligible for inclusion if they were 6 years old or older and belted in the rear of a 2000 or newer model year passenger vehicle within 10 model years of the crash year. Crashes were identified using the 2004–2015 National Automotive Sampling System Crashworthiness Data System (NASS CDS) and included all eligible occupants with at least one AIS 3 or greater injury. Using these same inclusion criteria but split into younger (6 to 12 years) and older (55+ years) cohorts, fatal crashes were identified in the 2014– 2015 Fatality Analysis Reporting System (FARS) then local police jurisdictions were contacted for complete crash records.
Results: Detailed case series review was completed for 117 rear-seat occupants: 36 with MAIS 3+ injuries in NASS CDS and 81 fatalities identified in FARS. More than half of the injured and killed rear occupants were more severely injured than front occupants in the same crash. Serious chest injury, primarily caused by seat belt loading, was present in 22 of the injured occupants and 17 of the 37 fatalities with documented injuries. Nine injured occupants and 18 fatalities sustained serious head injury, primarily from contact with the vehicle interior or severe intrusion. For fatal cases, 12 crashes were considered unsurvivable due to a complete loss of occupant space. For cases considered survivable, intrusion was not a large contributor to fatality.
Discussion: Rear-seat occupants sustained serious and fatal injuries due to belt loading in crashes in which front-seat occupants survived, suggesting a discrepancy in restraint performance between the front and rear rows. Restraint strategies that reduce loading to the chest should be considered, but there may be potential tradeoffs with increased head excursion, particularly in the absence of rear-seat airbags. Any new restraint designs should consider the unique needs of the rear-seat environment.
|2009||Forman J, Lopez-Valdes F, Lessley D, Kindig M, Kent R, Ridella S, Bostrom O. Rear seat occupant safety: an investigation of a progressive force-limiting, pretensioning 3-point belt system using adult PMHS in frontal sled tests. Stapp Car Crash J. 2009;53:49-74. SAE 2009-22-0002.|
|2008||Forman J, Michaelson J, Kent R, Kuppa S, Bostrom O. Occupant restraint in the rear seat: ATD responses to standard and pre-tensioning, force-limiting belt restraints. In: 52nd Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 6-8, 2008; San Diego, CA.141-153.|
|2017||Hu J, Reed MP, Rupp JD, Fischer K, Lange P, Adler A. Optimizing seat belt and airbag designs for rear seat occupant protection in frontal crashes. Stapp Car Crash J. November 2017;61:67-100. SAE 2017-22-0004.|
|2007||Winston FK, Xie D, Durbin DR, Elliott MR. Are child passengers bringing up the rear? evidence for differential improvements in injury risk between drivers and their child passengers. In: 51st Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 15-17, 2007; Melbourne, Australia.113-127.|
|2007||Brumbelow ML, Baker BC, Nolan JM. Effects of seat belt load limiters on driver fatalities in frontal crashes of passenger cars. In: Proceedings of the 20th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 18-21, 2007; Lyon, France.|
|2005||Kuppa S, Saunders J, Fessahaie O. Rear seat occupant protection in frontal crashes. In: Proceedings of the 19th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 6-9, 2005; Washington, DC.|
|1998||Stucki SL, Fessahaie O. Comparison of measured velocity change in frontal crash tests to NASS computed velocity change. In: Proceedings of the SAE International Congress & Exposition. February 23-26, 1998; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 980649.|
|2010||Bilston LE, Du W, Brown J. A matched-cohort analysis of belted front and rear seat occupants in newer and older model vehicles shows that gains in front occupant safety have outpaced gains for rear seat occupants. Accid Anal Prev. November 2010;42(6):1974-1977.|
|2001||Durbin DR, Arbogast KB, Moll EK. Seat belt syndrome in children: a case report and review of the literature. Pediatr Emerg Care. December 2001;17(6):474-477.|
|2003||Parenteau C, Viano DC. Field data analysis of rear occupant injuries, I: adults and teenagers. In: Proceedings of the SAE World Congress & Exhibition. March 3-6, 2003; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2003-01-0153.|
|2012||Arbogast KB, Locey CM, Zonfrillo MR. Differences in thoracic injury causation patterns between seat belt restrained children and adults. In: 56th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 14-17, 2012; Seattle, WA.213-220.|
|2004||Nance ML, Lutz N, Arbogast KB, Cornejo RA, Kallan MJ, Winston FK, Durbin DR. Optimal restraint reduces the risk of abdominal injury in children involved in motor vehicle crashes. Ann Surg. January 2004;239(1):127-131.|
|1998||Nolan JM, Preuss CA, Jones SL, O’Neill B. An update on the relationships between computed delta Vs and impact speeds for offset crash tests. In: Proceedings of the 16th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 31–June 4, 1998; Windsor, Ontario, Canada.1234-1241.|
|2011||Sundararajan S, Rouhana SW, Board D, DeSmet E, Prasad P, Rupp JD, Miller CS, Schneider LW. Biomechanical assessment of a rear-seat inflatable seatbelt in frontal impacts. Stapp Car Crash J. 2011;55:161-197.|
|1998||Braver ER, Whitfield R, Ferguson SA. Seating positions and children’s risk of dying in motor vehicle crashes. Inj Prev. 1998;4(3):181-187.|
|2012||Locey CM, Garcia-Espana JF, Toh A, Belwadi A, Arbogast KB, Maltese MR. Homogenization of vehicle fleet frontal crash pulses from 2000-2010. In: 56th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 14-17, 2012; Seattle, WA.299-311.|
|2005||Durbin DR, Chen I, Smith R, Elliott MR, Winston FK. Effects of seating position and appropriate restraint use on the risk of injury to children in motor vehicle crashes. Pediatrics. March 2005;115(3):e305-e309.|
|2003||Sherwood CP, Ferguson SA, Crandall JR. Factors leading to crash fatalities to children in child restraints. In: 47th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). September 22-24, 2003; Lisbon, Portugal.343-359.|
|2017||Edwards MA, Nash CE. Inflatable shoulder belts and inboard upper anchor shoulder‐belt geometry in far‐side oblique impacts. In: Proceedings of the 2017 International IRCOBI Conference on the Biomechanics of Injury. September 13-15, 2017; Antwerp, Belgium.373-389.|
|2010||Sahraei E, Digges K, Marzougui D. Reduced protection for belted occupants in rear seats relative to front seats of new model year vehicles. In: 54th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). October 17-20, 2010; Las Vegas, NV.149-158.|